From 7ed3b49ac610ba24a5356f7e62bea5dec52b3e47 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael_grund@gmx.de>
Date: Wed, 17 Feb 2021 19:28:53 +0100
Subject: [PATCH 01/17] Add new modules to plot horizontal and vertical lines

As discussed in #670 here's a new module (**hlines**) to plot a single or a set of horizontal lines with only defining the desired y-value(s). For discussion I only add the module for horizontal lines at the moment, however, the adjustments to prepare the same for vertical lines is done very quickly.
---
 pygmt/src/hlines.py | 155 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)
 create mode 100644 pygmt/src/hlines.py

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
new file mode 100644
index 00000000000..37a69dcd11f
--- /dev/null
+++ b/pygmt/src/hlines.py
@@ -0,0 +1,155 @@
+"""
+hlines - Plot horizontal lines.
+"""
+import numpy as np
+from pygmt.clib import Session
+from pygmt.exceptions import GMTInvalidInput
+from pygmt.helpers import build_arg_string, fmt_docstring, use_alias, kwargs_to_strings, data_kind
+
+@fmt_docstring
+@use_alias(
+        B="frame",
+        C="cmap",
+        D="offset",
+        J="projection",
+        N="no_clip",
+        R="region",
+        U="timestamp",
+        V="verbose",
+        W="pen",
+        X="xshift",
+        Y="yshift",
+        Z="zvalue",
+        l="label",
+        p="perspective",
+        t="transparency",
+    )
+@kwargs_to_strings(R="sequence", p="sequence")
+def hlines(self, y=None, xmin=None, xmax=None, pen=None, label=None, **kwargs):
+    """"
+    Plot one or a collection of horizontal lines 
+
+    Takes a single y value or a list of individual y values and optionally 
+    lower and upper x value limits as input.
+
+    Must provide *y*.
+
+    If y values are given without x limits then the current map boundaries are 
+    used as lower and upper limits. If only a single set of x limits is given then 
+    all lines will have the same length, otherwise give x limits for each individual 
+    line. If only a single label is given then all lines are grouped under this label 
+    in the legend (if shown). If each line should appear as a single entry in the 
+    legend, give corresponding labels for all lines (same for **pen**). 
+
+    Parameters
+    ----------
+    y : float or 1d array
+        The y coordinates or an array of y coordinates of the
+        horizontal lines to plot.
+    {J}
+    {R}
+    {B}
+    {CPT}
+    offset : str
+        ``dx/dy``.
+        Offset the line locations by the given amounts
+        *dx/dy* [Default is no offset]. If *dy* is not given it is set
+        equal to *dx*.
+    no_clip : bool or str
+        ``'[c|r]'``.
+        Do NOT clip lines that fall outside map border [Default plots
+        lines whose coordinates are strictly inside the map border only].
+        The option does not apply to lines which are always
+        clipped to the map region. For periodic (360-longitude) maps we
+        must plot all lines twice in case they are clipped by the
+        repeating boundary. ``no_clip=True`` will turn off clipping and not
+        plot repeating lines. Use ``no_clip="r"`` to turn off clipping
+        but retain the plotting of such repeating lines, or use
+        ``no_clip="c"`` to retain clipping but turn off plotting of
+        repeating lines.
+    {W}
+    {U}
+    {V}
+    {XY}
+    zvalue : str or float
+        ``value``.
+        Instead of specifying a line color via **pen**, give it a *value* 
+        via **zvalue** and a color lookup table via **cmap**. Requires appending
+         **+z** to **pen** (e.g. ``pen = "5p,+z"``, ``zvalue = 0.8``, 
+         * ``cmap = "viridis"``).
+    label : str
+        Add a legend entry for the line being plotted.
+    {p}
+    {t}
+        *transparency* can also be a 1d array to set varying transparency
+        for lines.
+
+    """
+        
+    kwargs = self._preprocess(**kwargs)
+ 
+    list_length = len(np.atleast_1d(y))
+        
+    # prepare x vals
+    if xmin is None and xmax is None: 
+        # get limits from current map boundings if not given via xmin, xmax
+        with Session() as lib:   
+            mapbnds = lib.extract_region() 
+            x = np.array([[mapbnds[0]], [mapbnds[1]]])  
+            x = np.repeat(x, list_length, axis=1)         
+    elif xmin is None or xmax is None:
+        raise GMTInvalidInput("Must provide both, xmin and xmax if limits are not set automatically.")         
+        
+    else:   
+        # if only a single xmin and xmax without [], repeat to fit size of y
+        if isinstance(xmin, int) or isinstance(xmin, float):  
+            x = np.array([[xmin], [xmax]])  
+            x = np.repeat(x, list_length, axis=1)    
+        else:
+            if len(xmin) != len(xmax):
+                GMTInvalidInput("Must provide same length for xmin and xmax.") 
+            else:   
+                x = np.array([xmin, xmax])  
+              
+    # prepare labels         
+    if "l" in kwargs:
+        # if several lines belong to the same label, first take the label,
+        # then set all to None and reset the first entry to the given label
+        if not isinstance(kwargs["l"], list):
+            label2use = kwargs["l"]
+            kwargs["l"] = np.repeat(None, list_length)
+            kwargs["l"][0] = label2use   
+    else:
+        kwargs["l"] = np.repeat(None, list_length)   
+        
+      
+    # prepare pens    
+    if "W" in kwargs:
+        # select pen, no series
+        if not isinstance(kwargs["W"], list):
+            pen2use = kwargs["W"]
+            kwargs["W"] = np.repeat(pen2use, list_length)   
+    else: # use as default if no pen is given (neither single nor series)
+        kwargs["W"] = np.repeat("1p,black", list_length)
+
+    # loop over entries  
+    kwargs_copy = kwargs.copy()
+        
+    for index in range(list_length):
+            y2plt = [np.atleast_1d(y)[index], np.atleast_1d(y)[index]]
+            x2plt = [np.atleast_1d(x)[0][index], np.atleast_1d(x)[1][index]]
+            kind = data_kind(None, x2plt, y2plt)
+
+            with Session() as lib:
+                if kind == "vectors":
+                    file_context = lib.virtualfile_from_vectors(
+                        np.atleast_1d(x2plt), np.atleast_1d(y2plt))  
+                else: 
+                    raise GMTInvalidInput("Unrecognized data type.")
+        
+                kwargs["l"] = kwargs_copy["l"][index]
+                kwargs["W"] = kwargs_copy["W"][index]
+                
+                with file_context as fname:
+                    arg_str = " ".join([fname, build_arg_string(kwargs)])
+                    lib.call_module("plot", arg_str)

From 096b9de601c68bb17d3ac3e2e9796e881679b600 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 17 Feb 2021 19:42:07 +0100
Subject: [PATCH 02/17] added further content

---
 doc/api/index.rst                         |   1 +
 examples/gallery/line/horizontal-lines.py |  29 ++++
 pygmt/figure.py                           |   1 +
 pygmt/src/__init__.py                     |   1 +
 pygmt/src/hlines.py                       | 161 ++++++++++++----------
 5 files changed, 117 insertions(+), 76 deletions(-)
 create mode 100644 examples/gallery/line/horizontal-lines.py

diff --git a/doc/api/index.rst b/doc/api/index.rst
index 0ef0b359b39..f56e3d0b3e1 100644
--- a/doc/api/index.rst
+++ b/doc/api/index.rst
@@ -31,6 +31,7 @@ Plotting data and laying out the map:
     Figure.grdview
     Figure.image
     Figure.inset
+    Figure.hlines
     Figure.legend
     Figure.logo
     Figure.meca
diff --git a/examples/gallery/line/horizontal-lines.py b/examples/gallery/line/horizontal-lines.py
new file mode 100644
index 00000000000..cfbe3066586
--- /dev/null
+++ b/examples/gallery/line/horizontal-lines.py
@@ -0,0 +1,29 @@
+"""
+Plot horizontal lines
+---------------------
+
+The :meth:`pygmt.Figure.hlines` method can plot horizontal lines based on 
+a given y value. Optionally, the lower and upper limits of the lines can be
+defined, otherwise the current map boundaries are taken. 
+
+"""
+
+import pygmt
+
+fig = pygmt.Figure()
+fig.basemap(region=[0, 10, 0, 11], projection="X10c/10c", frame=True)
+
+fig.hlines(1, label="line1")
+fig.hlines([2, 3], pen="2p,dodgerblue4", label="line2")
+fig.hlines([4, 5], xmin=2, xmax=8, pen="2p,red3", label="line3")
+fig.hlines([6, 7], xmin=[1, 3], xmax=[8, 7], pen="3p,seagreen", label="line4")
+fig.hlines(
+    [8, 9, 10],
+    xmin=[1.3, 3, 2],
+    xmax=[6.5, 7, 5],
+    pen=["4p,darkmagenta", "2p,gold,--", "3.5p,blue,."],
+    label=["line5", "line6", "line7"],
+)
+
+fig.legend()
+fig.show()
diff --git a/pygmt/figure.py b/pygmt/figure.py
index 92699cd8632..72df6e40c4a 100644
--- a/pygmt/figure.py
+++ b/pygmt/figure.py
@@ -383,6 +383,7 @@ def _repr_html_(self):
         grdcontour,
         grdimage,
         grdview,
+        hlines,
         image,
         inset,
         legend,
diff --git a/pygmt/src/__init__.py b/pygmt/src/__init__.py
index 3ef9af36070..2b0e0c2329b 100644
--- a/pygmt/src/__init__.py
+++ b/pygmt/src/__init__.py
@@ -15,6 +15,7 @@
 from pygmt.src.grdinfo import grdinfo
 from pygmt.src.grdtrack import grdtrack
 from pygmt.src.grdview import grdview
+from pygmt.src.hlines import hlines
 from pygmt.src.image import image
 from pygmt.src.info import info
 from pygmt.src.inset import inset
diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 37a69dcd11f..31d6250d6a8 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -4,42 +4,50 @@
 import numpy as np
 from pygmt.clib import Session
 from pygmt.exceptions import GMTInvalidInput
-from pygmt.helpers import build_arg_string, fmt_docstring, use_alias, kwargs_to_strings, data_kind
+from pygmt.helpers import (
+    build_arg_string,
+    data_kind,
+    fmt_docstring,
+    kwargs_to_strings,
+    use_alias,
+)
+
 
 @fmt_docstring
 @use_alias(
-        B="frame",
-        C="cmap",
-        D="offset",
-        J="projection",
-        N="no_clip",
-        R="region",
-        U="timestamp",
-        V="verbose",
-        W="pen",
-        X="xshift",
-        Y="yshift",
-        Z="zvalue",
-        l="label",
-        p="perspective",
-        t="transparency",
-    )
+    B="frame",
+    C="cmap",
+    D="offset",
+    J="projection",
+    N="no_clip",
+    R="region",
+    U="timestamp",
+    V="verbose",
+    W="pen",
+    X="xshift",
+    Y="yshift",
+    Z="zvalue",
+    l="label",
+    p="perspective",
+    t="transparency",
+)
 @kwargs_to_strings(R="sequence", p="sequence")
 def hlines(self, y=None, xmin=None, xmax=None, pen=None, label=None, **kwargs):
-    """"
-    Plot one or a collection of horizontal lines 
+    """
+    " Plot one or a collection of horizontal lines.
 
-    Takes a single y value or a list of individual y values and optionally 
+    Takes a single y value or a list of individual y values and optionally
     lower and upper x value limits as input.
 
     Must provide *y*.
 
-    If y values are given without x limits then the current map boundaries are 
-    used as lower and upper limits. If only a single set of x limits is given then 
-    all lines will have the same length, otherwise give x limits for each individual 
-    line. If only a single label is given then all lines are grouped under this label 
-    in the legend (if shown). If each line should appear as a single entry in the 
-    legend, give corresponding labels for all lines (same for **pen**). 
+    If y values are given without x limits then the current map boundaries are
+    used as lower and upper limits. If only a single set of x limits is given
+    then all lines will have the same length, otherwise give x limits for each
+    individual line. If only a single label is given then all lines are grouped
+    under this label in the legend (if shown). If each line should appear as a
+    single entry in the legend, give corresponding labels for all lines
+    (same for **pen**).
 
     Parameters
     ----------
@@ -73,83 +81,84 @@ def hlines(self, y=None, xmin=None, xmax=None, pen=None, label=None, **kwargs):
     {XY}
     zvalue : str or float
         ``value``.
-        Instead of specifying a line color via **pen**, give it a *value* 
-        via **zvalue** and a color lookup table via **cmap**. Requires appending
-         **+z** to **pen** (e.g. ``pen = "5p,+z"``, ``zvalue = 0.8``, 
-         * ``cmap = "viridis"``).
+        Instead of specifying a line color via **pen**, give it a *value*
+        via **zvalue** and a color lookup table via **cmap**. Requires
+        appending **+z** to **pen** (e.g. ``pen = "5p,+z"``,
+        ``zvalue = 0.8``, ``cmap = "viridis"``).
     label : str
         Add a legend entry for the line being plotted.
     {p}
     {t}
         *transparency* can also be a 1d array to set varying transparency
         for lines.
-
     """
-        
+
     kwargs = self._preprocess(**kwargs)
- 
+
     list_length = len(np.atleast_1d(y))
-        
+
     # prepare x vals
-    if xmin is None and xmax is None: 
+    if xmin is None and xmax is None:
         # get limits from current map boundings if not given via xmin, xmax
-        with Session() as lib:   
-            mapbnds = lib.extract_region() 
-            x = np.array([[mapbnds[0]], [mapbnds[1]]])  
-            x = np.repeat(x, list_length, axis=1)         
+        with Session() as lib:
+            mapbnds = lib.extract_region()
+            x = np.array([[mapbnds[0]], [mapbnds[1]]])
+            x = np.repeat(x, list_length, axis=1)
     elif xmin is None or xmax is None:
-        raise GMTInvalidInput("Must provide both, xmin and xmax if limits are not set automatically.")         
-        
-    else:   
+        raise GMTInvalidInput(
+            "Must provide both, xmin and xmax if limits are not set automatically."
+        )
+
+    else:
         # if only a single xmin and xmax without [], repeat to fit size of y
-        if isinstance(xmin, int) or isinstance(xmin, float):  
-            x = np.array([[xmin], [xmax]])  
-            x = np.repeat(x, list_length, axis=1)    
+        if isinstance(xmin, int) or isinstance(xmin, float):
+            x = np.array([[xmin], [xmax]])
+            x = np.repeat(x, list_length, axis=1)
         else:
             if len(xmin) != len(xmax):
-                GMTInvalidInput("Must provide same length for xmin and xmax.") 
-            else:   
-                x = np.array([xmin, xmax])  
-              
-    # prepare labels         
+                GMTInvalidInput("Must provide same length for xmin and xmax.")
+            else:
+                x = np.array([xmin, xmax])
+
+    # prepare labels
     if "l" in kwargs:
         # if several lines belong to the same label, first take the label,
         # then set all to None and reset the first entry to the given label
         if not isinstance(kwargs["l"], list):
             label2use = kwargs["l"]
             kwargs["l"] = np.repeat(None, list_length)
-            kwargs["l"][0] = label2use   
+            kwargs["l"][0] = label2use
     else:
-        kwargs["l"] = np.repeat(None, list_length)   
-        
-      
-    # prepare pens    
+        kwargs["l"] = np.repeat(None, list_length)
+
+    # prepare pens
     if "W" in kwargs:
         # select pen, no series
         if not isinstance(kwargs["W"], list):
             pen2use = kwargs["W"]
-            kwargs["W"] = np.repeat(pen2use, list_length)   
-    else: # use as default if no pen is given (neither single nor series)
+            kwargs["W"] = np.repeat(pen2use, list_length)
+    else:  # use as default if no pen is given (neither single nor series)
         kwargs["W"] = np.repeat("1p,black", list_length)
 
-    # loop over entries  
+    # loop over entries
     kwargs_copy = kwargs.copy()
-        
+
     for index in range(list_length):
-            y2plt = [np.atleast_1d(y)[index], np.atleast_1d(y)[index]]
-            x2plt = [np.atleast_1d(x)[0][index], np.atleast_1d(x)[1][index]]
-            kind = data_kind(None, x2plt, y2plt)
-
-            with Session() as lib:
-                if kind == "vectors":
-                    file_context = lib.virtualfile_from_vectors(
-                        np.atleast_1d(x2plt), np.atleast_1d(y2plt))  
-                else: 
-                    raise GMTInvalidInput("Unrecognized data type.")
-        
-                kwargs["l"] = kwargs_copy["l"][index]
-                kwargs["W"] = kwargs_copy["W"][index]
-                
-                with file_context as fname:
-                    arg_str = " ".join([fname, build_arg_string(kwargs)])
-                    lib.call_module("plot", arg_str)
+        y2plt = [np.atleast_1d(y)[index], np.atleast_1d(y)[index]]
+        x2plt = [np.atleast_1d(x)[0][index], np.atleast_1d(x)[1][index]]
+        kind = data_kind(None, x2plt, y2plt)
+
+        with Session() as lib:
+            if kind == "vectors":
+                file_context = lib.virtualfile_from_vectors(
+                    np.atleast_1d(x2plt), np.atleast_1d(y2plt)
+                )
+            else:
+                raise GMTInvalidInput("Unrecognized data type.")
+
+            kwargs["l"] = kwargs_copy["l"][index]
+            kwargs["W"] = kwargs_copy["W"][index]
+
+            with file_context as fname:
+                arg_str = " ".join([fname, build_arg_string(kwargs)])
+                lib.call_module("plot", arg_str)

From 92fa9c078315c0323e247c7de54bdb3f98899c03 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 17 Feb 2021 19:49:19 +0100
Subject: [PATCH 03/17] added some first tests

---
 pygmt/tests/test_hlines.py | 73 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 pygmt/tests/test_hlines.py

diff --git a/pygmt/tests/test_hlines.py b/pygmt/tests/test_hlines.py
new file mode 100644
index 00000000000..021e936ba53
--- /dev/null
+++ b/pygmt/tests/test_hlines.py
@@ -0,0 +1,73 @@
+"""
+Tests for hline.
+"""
+from pygmt import Figure
+from pygmt.helpers.testing import check_figures_equal
+
+
+@check_figures_equal()
+def test_hlines_value_sets():
+    """
+    Passing sets of y, xmin and xmax.
+    """
+
+    fig_ref, fig_test = Figure(), Figure()
+
+    fig_ref.hlines(
+        region=[0, 10, 0, 20],
+        projection="X10c/10c",
+        frame=True,
+        y=[5.5, 10, 6, 11],
+        xmin=[3.1, 6, 0, 1],
+        xmax=[5.5, 7.8, 10, 9],
+        label="test2",
+        pen="4p,green",
+    )
+
+    fig_test.hlines(
+        region="0/10/0/20",
+        projection="X10c/10c",
+        frame=True,
+        y=[5.5, 10, 6, 11],
+        xmin=[3.1, 6, 0, 1],
+        xmax=[5.5, 7.8, 10, 9],
+        label="test2",
+        pen="4p,green",
+    )
+
+    return fig_ref, fig_test
+
+
+@check_figures_equal()
+def test_hlines_zvalue():
+    """
+    Passing in color via zvalue.
+    """
+
+    fig_ref, fig_test = Figure(), Figure()
+
+    fig_ref.hlines(
+        region=[0, 10, 0, 20],
+        projection="X10c/10c",
+        frame=True,
+        y=[9.9],
+        xmin=2,
+        xmax=6,
+        pen="5p,+z",
+        zvalue="0.5",
+        cmap="magma",
+    )
+
+    fig_test.hlines(
+        region="0/10/0/20",
+        projection="X10c/10c",
+        frame=True,
+        y=[9.9],
+        xmin=2,
+        xmax=6,
+        pen="5p,+z",
+        zvalue="0.5",
+        cmap="magma",
+    )
+
+    return fig_ref, fig_test

From 975b3050c81fc85c7329fd93ebcf12df5f31f616 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 17 Feb 2021 19:58:06 +0100
Subject: [PATCH 04/17] some formatting

---
 pygmt/src/hlines.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 31d6250d6a8..058b83c0af6 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -32,7 +32,7 @@
     t="transparency",
 )
 @kwargs_to_strings(R="sequence", p="sequence")
-def hlines(self, y=None, xmin=None, xmax=None, pen=None, label=None, **kwargs):
+def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
     """
     " Plot one or a collection of horizontal lines.
 
@@ -111,7 +111,7 @@ def hlines(self, y=None, xmin=None, xmax=None, pen=None, label=None, **kwargs):
 
     else:
         # if only a single xmin and xmax without [], repeat to fit size of y
-        if isinstance(xmin, int) or isinstance(xmin, float):
+        if isinstance(xmin, (int, float)):
             x = np.array([[xmin], [xmax]])
             x = np.repeat(x, list_length, axis=1)
         else:

From f25a89c4d0a38fedfffeb5cf9da98ef16ff7e17f Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 17 Feb 2021 20:07:07 +0100
Subject: [PATCH 05/17] corrected typo

---
 pygmt/src/hlines.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 058b83c0af6..95a6ca43f64 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -34,7 +34,7 @@
 @kwargs_to_strings(R="sequence", p="sequence")
 def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
     """
-    " Plot one or a collection of horizontal lines.
+    Plot one or a collection of horizontal lines.
 
     Takes a single y value or a list of individual y values and optionally
     lower and upper x value limits as input.

From d0bc35c0a3528f95540b6ab7c6a0163f1769b372 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 7 Apr 2021 18:57:57 +0200
Subject: [PATCH 06/17] moved gallery example to new subfolder /lines

---
 examples/gallery/{line => lines}/horizontal-lines.py | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename examples/gallery/{line => lines}/horizontal-lines.py (100%)

diff --git a/examples/gallery/line/horizontal-lines.py b/examples/gallery/lines/horizontal-lines.py
similarity index 100%
rename from examples/gallery/line/horizontal-lines.py
rename to examples/gallery/lines/horizontal-lines.py

From f75fbe1797a2ac24dc51ba79dbb65e2768b83a73 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 7 Apr 2021 19:04:43 +0200
Subject: [PATCH 07/17] disable pylint warnings

---
 pygmt/src/hlines.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 95a6ca43f64..c2f96819bb2 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -93,7 +93,7 @@ def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
         for lines.
     """
 
-    kwargs = self._preprocess(**kwargs)
+    kwargs = self._preprocess(**kwargs) # pylint: disable=protected-access
 
     list_length = len(np.atleast_1d(y))
 

From a375a778482f9b4ddfbb0cb32300a0d4f9985a33 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 7 Apr 2021 19:08:43 +0200
Subject: [PATCH 08/17] replace hyphen by underscore in gallery example file
 name

---
 .../gallery/lines/{horizontal-lines.py => horizontal_lines.py}    | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename examples/gallery/lines/{horizontal-lines.py => horizontal_lines.py} (100%)

diff --git a/examples/gallery/lines/horizontal-lines.py b/examples/gallery/lines/horizontal_lines.py
similarity index 100%
rename from examples/gallery/lines/horizontal-lines.py
rename to examples/gallery/lines/horizontal_lines.py

From 71113dd38aa9d9b57fc71dc5d7c90c65dc04a9cf Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 7 Apr 2021 19:26:44 +0200
Subject: [PATCH 09/17] disable pylint warnings

---
 pygmt/src/hlines.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index c2f96819bb2..245ee35d613 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -93,6 +93,10 @@ def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
         for lines.
     """
 
+    # appearing pylint warnings that need to be fixed
+    # pylint: disable=too-many-locals
+    # pylint: disable=too-many-branches
+
     kwargs = self._preprocess(**kwargs) # pylint: disable=protected-access
 
     list_length = len(np.atleast_1d(y))

From 1438d4340e5911f927189ad20fb86a1713e1c23b Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 7 Apr 2021 19:29:23 +0200
Subject: [PATCH 10/17] formatting

---
 pygmt/src/hlines.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 245ee35d613..7f4d8caae05 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -97,7 +97,7 @@ def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
     # pylint: disable=too-many-locals
     # pylint: disable=too-many-branches
 
-    kwargs = self._preprocess(**kwargs) # pylint: disable=protected-access
+    kwargs = self._preprocess(**kwargs)  # pylint: disable=protected-access
 
     list_length = len(np.atleast_1d(y))
 

From 65eb85d2bcd92d21a2663cc4af0d2566562c6ce3 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Tue, 10 Aug 2021 21:03:17 +0200
Subject: [PATCH 11/17] update hlines module

---
 examples/gallery/lines/horizontal_lines.py |  15 ++-
 pygmt/src/hlines.py                        | 139 ++++++++-------------
 2 files changed, 61 insertions(+), 93 deletions(-)

diff --git a/examples/gallery/lines/horizontal_lines.py b/examples/gallery/lines/horizontal_lines.py
index cfbe3066586..5e027f2fe20 100644
--- a/examples/gallery/lines/horizontal_lines.py
+++ b/examples/gallery/lines/horizontal_lines.py
@@ -17,13 +17,12 @@
 fig.hlines([2, 3], pen="2p,dodgerblue4", label="line2")
 fig.hlines([4, 5], xmin=2, xmax=8, pen="2p,red3", label="line3")
 fig.hlines([6, 7], xmin=[1, 3], xmax=[8, 7], pen="3p,seagreen", label="line4")
-fig.hlines(
-    [8, 9, 10],
-    xmin=[1.3, 3, 2],
-    xmax=[6.5, 7, 5],
-    pen=["4p,darkmagenta", "2p,gold,--", "3.5p,blue,."],
-    label=["line5", "line6", "line7"],
-)
+fig.hlines([8, 9, 10],
+           xmin=[1.3, 3, 2],
+           xmax=[6.5, 7, 5],
+           pen=["4p,darkmagenta","2p,gold,--","3.5p,blue,."],
+           label=["line5", "line6", "line7"],
+           transparency = 50)
 
 fig.legend()
-fig.show()
+fig.show()
\ No newline at end of file
diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 7f4d8caae05..54ecf756936 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -12,35 +12,22 @@
     use_alias,
 )
 
-
 @fmt_docstring
 @use_alias(
-    B="frame",
-    C="cmap",
-    D="offset",
-    J="projection",
     N="no_clip",
-    R="region",
-    U="timestamp",
     V="verbose",
     W="pen",
-    X="xshift",
-    Y="yshift",
-    Z="zvalue",
     l="label",
     p="perspective",
     t="transparency",
-)
-@kwargs_to_strings(R="sequence", p="sequence")
+    )
+@kwargs_to_strings(p="sequence")
 def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
     """
     Plot one or a collection of horizontal lines.
-
     Takes a single y value or a list of individual y values and optionally
     lower and upper x value limits as input.
-
     Must provide *y*.
-
     If y values are given without x limits then the current map boundaries are
     used as lower and upper limits. If only a single set of x limits is given
     then all lines will have the same length, otherwise give x limits for each
@@ -48,21 +35,11 @@ def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
     under this label in the legend (if shown). If each line should appear as a
     single entry in the legend, give corresponding labels for all lines
     (same for **pen**).
-
     Parameters
     ----------
     y : float or 1d array
         The y coordinates or an array of y coordinates of the
         horizontal lines to plot.
-    {J}
-    {R}
-    {B}
-    {CPT}
-    offset : str
-        ``dx/dy``.
-        Offset the line locations by the given amounts
-        *dx/dy* [Default is no offset]. If *dy* is not given it is set
-        equal to *dx*.
     no_clip : bool or str
         ``'[c|r]'``.
         Do NOT clip lines that fall outside map border [Default plots
@@ -76,87 +53,80 @@ def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
         ``no_clip="c"`` to retain clipping but turn off plotting of
         repeating lines.
     {W}
-    {U}
     {V}
-    {XY}
-    zvalue : str or float
-        ``value``.
-        Instead of specifying a line color via **pen**, give it a *value*
-        via **zvalue** and a color lookup table via **cmap**. Requires
-        appending **+z** to **pen** (e.g. ``pen = "5p,+z"``,
-        ``zvalue = 0.8``, ``cmap = "viridis"``).
     label : str
         Add a legend entry for the line being plotted.
     {p}
     {t}
         *transparency* can also be a 1d array to set varying transparency
         for lines.
-    """
 
-    # appearing pylint warnings that need to be fixed
-    # pylint: disable=too-many-locals
-    # pylint: disable=too-many-branches
+    """
 
     kwargs = self._preprocess(**kwargs)  # pylint: disable=protected-access
 
-    list_length = len(np.atleast_1d(y))
+    y = np.atleast_1d(y)
+    list_length = len(y)
+
+    # prepare x values
+    def prep_data(xmin, xmax, list_length):
+
+        if xmin is None and xmax is None:
+            with Session() as lib:
+                # get limits from current map boundings if not given via xmin, xmax
+                x = np.array([[lib.extract_region()[0]], [lib.extract_region()[1]]])
+                x = np.repeat(x, list_length, axis=1)
+        elif xmin is None or xmax is None:
+            raise GMTInvalidInput(
+                "Must provide both, xmin and xmax if limits are not set automatically."
+            )
 
-    # prepare x vals
-    if xmin is None and xmax is None:
-        # get limits from current map boundings if not given via xmin, xmax
-        with Session() as lib:
-            mapbnds = lib.extract_region()
-            x = np.array([[mapbnds[0]], [mapbnds[1]]])
-            x = np.repeat(x, list_length, axis=1)
-    elif xmin is None or xmax is None:
-        raise GMTInvalidInput(
-            "Must provide both, xmin and xmax if limits are not set automatically."
-        )
-
-    else:
-        # if only a single xmin and xmax without [], repeat to fit size of y
-        if isinstance(xmin, (int, float)):
-            x = np.array([[xmin], [xmax]])
-            x = np.repeat(x, list_length, axis=1)
         else:
-            if len(xmin) != len(xmax):
-                GMTInvalidInput("Must provide same length for xmin and xmax.")
+            # if only a single xmin and xmax without [], repeat to fit size of y
+            if isinstance(xmin, (int, float)):
+                x = np.array([[xmin], [xmax]])
+                x = np.repeat(x, list_length, axis=1)
             else:
-                x = np.array([xmin, xmax])
-
-    # prepare labels
-    if "l" in kwargs:
-        # if several lines belong to the same label, first take the label,
-        # then set all to None and reset the first entry to the given label
-        if not isinstance(kwargs["l"], list):
-            label2use = kwargs["l"]
+                if len(xmin) != len(xmax):
+                    GMTInvalidInput("Must provide same length for xmin and xmax.")
+                else:
+                    x = np.array([xmin, xmax])
+
+        return np.atleast_1d(x)
+
+    def prep_style(kwargs, list_length):
+
+        # prepare labels
+        if "l" in kwargs:
+            # if several lines belong to the same label, first set all to the
+            # label given via "l", then reset all entries except the first
+            if not isinstance(kwargs["l"], list):
+                kwargs["l"] = np.repeat(kwargs["l"], list_length)
+                kwargs["l"][1:list_length] = None
+        else:
             kwargs["l"] = np.repeat(None, list_length)
-            kwargs["l"][0] = label2use
-    else:
-        kwargs["l"] = np.repeat(None, list_length)
-
-    # prepare pens
-    if "W" in kwargs:
-        # select pen, no series
-        if not isinstance(kwargs["W"], list):
-            pen2use = kwargs["W"]
-            kwargs["W"] = np.repeat(pen2use, list_length)
-    else:  # use as default if no pen is given (neither single nor series)
-        kwargs["W"] = np.repeat("1p,black", list_length)
+
+        # prepare pens
+        if "W" in kwargs:
+            # select pen, no series
+            if not isinstance(kwargs["W"], list):
+                kwargs["W"] = np.repeat(kwargs["W"], list_length)
+        else:  # use as default if no pen is given (neither single nor series)
+            kwargs["W"] = np.repeat("1p,black", list_length)
+
+        return kwargs
 
     # loop over entries
+    x = prep_data(xmin, xmax, list_length)
+    kwargs = prep_style(kwargs, list_length)
     kwargs_copy = kwargs.copy()
 
     for index in range(list_length):
-        y2plt = [np.atleast_1d(y)[index], np.atleast_1d(y)[index]]
-        x2plt = [np.atleast_1d(x)[0][index], np.atleast_1d(x)[1][index]]
-        kind = data_kind(None, x2plt, y2plt)
 
         with Session() as lib:
-            if kind == "vectors":
+            if data_kind(None, [x[0][index], x[1][index]], [y[index], y[index]]) == "vectors":
                 file_context = lib.virtualfile_from_vectors(
-                    np.atleast_1d(x2plt), np.atleast_1d(y2plt)
-                )
+                    np.atleast_1d([x[0][index], x[1][index]]), [y[index], y[index]])
             else:
                 raise GMTInvalidInput("Unrecognized data type.")
 
@@ -164,5 +134,4 @@ def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
             kwargs["W"] = kwargs_copy["W"][index]
 
             with file_context as fname:
-                arg_str = " ".join([fname, build_arg_string(kwargs)])
-                lib.call_module("plot", arg_str)
+                lib.call_module("plot", " ".join([fname, build_arg_string(kwargs)]))

From 49008eda7da1536188be47024a5d185a52d4c8c0 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Tue, 10 Aug 2021 21:08:20 +0200
Subject: [PATCH 12/17] formatting

---
 examples/gallery/lines/horizontal_lines.py | 16 +++++++++-------
 pygmt/figure.py                            |  2 +-
 pygmt/src/__init__.py                      |  2 +-
 pygmt/src/hlines.py                        | 11 ++++++++---
 4 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/examples/gallery/lines/horizontal_lines.py b/examples/gallery/lines/horizontal_lines.py
index 5e027f2fe20..0ce5490c7ee 100644
--- a/examples/gallery/lines/horizontal_lines.py
+++ b/examples/gallery/lines/horizontal_lines.py
@@ -17,12 +17,14 @@
 fig.hlines([2, 3], pen="2p,dodgerblue4", label="line2")
 fig.hlines([4, 5], xmin=2, xmax=8, pen="2p,red3", label="line3")
 fig.hlines([6, 7], xmin=[1, 3], xmax=[8, 7], pen="3p,seagreen", label="line4")
-fig.hlines([8, 9, 10],
-           xmin=[1.3, 3, 2],
-           xmax=[6.5, 7, 5],
-           pen=["4p,darkmagenta","2p,gold,--","3.5p,blue,."],
-           label=["line5", "line6", "line7"],
-           transparency = 50)
+fig.hlines(
+    [8, 9, 10],
+    xmin=[1.3, 3, 2],
+    xmax=[6.5, 7, 5],
+    pen=["4p,darkmagenta", "2p,gold,--", "3.5p,blue,."],
+    label=["line5", "line6", "line7"],
+    transparency=50,
+)
 
 fig.legend()
-fig.show()
\ No newline at end of file
+fig.show()
diff --git a/pygmt/figure.py b/pygmt/figure.py
index 759b2c1f48d..9092f977684 100644
--- a/pygmt/figure.py
+++ b/pygmt/figure.py
@@ -422,8 +422,8 @@ def _repr_html_(self):
         grdcontour,
         grdimage,
         grdview,
-        hlines,
         histogram,
+        hlines,
         image,
         inset,
         legend,
diff --git a/pygmt/src/__init__.py b/pygmt/src/__init__.py
index 2aebe291ca1..936b6875e47 100644
--- a/pygmt/src/__init__.py
+++ b/pygmt/src/__init__.py
@@ -22,8 +22,8 @@
 from pygmt.src.grdsample import grdsample
 from pygmt.src.grdtrack import grdtrack
 from pygmt.src.grdview import grdview
-from pygmt.src.hlines import hlines
 from pygmt.src.histogram import histogram
+from pygmt.src.hlines import hlines
 from pygmt.src.image import image
 from pygmt.src.info import info
 from pygmt.src.inset import inset
diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 54ecf756936..106ac5e45e8 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -12,6 +12,7 @@
     use_alias,
 )
 
+
 @fmt_docstring
 @use_alias(
     N="no_clip",
@@ -20,7 +21,7 @@
     l="label",
     p="perspective",
     t="transparency",
-    )
+)
 @kwargs_to_strings(p="sequence")
 def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
     """
@@ -124,9 +125,13 @@ def prep_style(kwargs, list_length):
     for index in range(list_length):
 
         with Session() as lib:
-            if data_kind(None, [x[0][index], x[1][index]], [y[index], y[index]]) == "vectors":
+            if (
+                data_kind(None, [x[0][index], x[1][index]], [y[index], y[index]])
+                == "vectors"
+            ):
                 file_context = lib.virtualfile_from_vectors(
-                    np.atleast_1d([x[0][index], x[1][index]]), [y[index], y[index]])
+                    np.atleast_1d([x[0][index], x[1][index]]), [y[index], y[index]]
+                )
             else:
                 raise GMTInvalidInput("Unrecognized data type.")
 

From 457bf72ddc4519c95b006640bf62161cc75aa6f3 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Tue, 10 Aug 2021 21:12:29 +0200
Subject: [PATCH 13/17] adjust docstring

---
 pygmt/src/hlines.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 106ac5e45e8..6c1caae43bb 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -74,7 +74,8 @@ def prep_data(xmin, xmax, list_length):
 
         if xmin is None and xmax is None:
             with Session() as lib:
-                # get limits from current map boundings if not given via xmin, xmax
+                # get limits from current map boundings if not given
+                # via xmin, xmax
                 x = np.array([[lib.extract_region()[0]], [lib.extract_region()[1]]])
                 x = np.repeat(x, list_length, axis=1)
         elif xmin is None or xmax is None:
@@ -83,7 +84,8 @@ def prep_data(xmin, xmax, list_length):
             )
 
         else:
-            # if only a single xmin and xmax without [], repeat to fit size of y
+            # if only a single xmin and xmax without [], repeat to fit size
+            # of y
             if isinstance(xmin, (int, float)):
                 x = np.array([[xmin], [xmax]])
                 x = np.repeat(x, list_length, axis=1)

From f2c84a7bf8e1cf6c1ab779a3dab14a4ea73f5a1a Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Tue, 10 Aug 2021 21:26:51 +0200
Subject: [PATCH 14/17] adjust priliminary tests

---
 pygmt/tests/test_hlines.py | 43 ++------------------------------------
 1 file changed, 2 insertions(+), 41 deletions(-)

diff --git a/pygmt/tests/test_hlines.py b/pygmt/tests/test_hlines.py
index 021e936ba53..896aa68b14a 100644
--- a/pygmt/tests/test_hlines.py
+++ b/pygmt/tests/test_hlines.py
@@ -13,10 +13,8 @@ def test_hlines_value_sets():
 
     fig_ref, fig_test = Figure(), Figure()
 
+    fig_ref.basemap(region=[0, 10, 0, 20], projection="X10c/10c", frame=True)
     fig_ref.hlines(
-        region=[0, 10, 0, 20],
-        projection="X10c/10c",
-        frame=True,
         y=[5.5, 10, 6, 11],
         xmin=[3.1, 6, 0, 1],
         xmax=[5.5, 7.8, 10, 9],
@@ -24,10 +22,8 @@ def test_hlines_value_sets():
         pen="4p,green",
     )
 
+    fig_test.basemap(region="0/10/0/20", projection="X10c/10c", frame=True)
     fig_test.hlines(
-        region="0/10/0/20",
-        projection="X10c/10c",
-        frame=True,
         y=[5.5, 10, 6, 11],
         xmin=[3.1, 6, 0, 1],
         xmax=[5.5, 7.8, 10, 9],
@@ -36,38 +32,3 @@ def test_hlines_value_sets():
     )
 
     return fig_ref, fig_test
-
-
-@check_figures_equal()
-def test_hlines_zvalue():
-    """
-    Passing in color via zvalue.
-    """
-
-    fig_ref, fig_test = Figure(), Figure()
-
-    fig_ref.hlines(
-        region=[0, 10, 0, 20],
-        projection="X10c/10c",
-        frame=True,
-        y=[9.9],
-        xmin=2,
-        xmax=6,
-        pen="5p,+z",
-        zvalue="0.5",
-        cmap="magma",
-    )
-
-    fig_test.hlines(
-        region="0/10/0/20",
-        projection="X10c/10c",
-        frame=True,
-        y=[9.9],
-        xmin=2,
-        xmax=6,
-        pen="5p,+z",
-        zvalue="0.5",
-        cmap="magma",
-    )
-
-    return fig_ref, fig_test

From e7726c0d172c84469a464f1c9868b4a7b5f0448a Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 11 Aug 2021 18:32:05 +0200
Subject: [PATCH 15/17] update

---
 pygmt/src/hlines.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 6c1caae43bb..0c9e3153ee4 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -74,8 +74,7 @@ def prep_data(xmin, xmax, list_length):
 
         if xmin is None and xmax is None:
             with Session() as lib:
-                # get limits from current map boundings if not given
-                # via xmin, xmax
+                # get limits from current map boundings if not given via xmin, xmax
                 x = np.array([[lib.extract_region()[0]], [lib.extract_region()[1]]])
                 x = np.repeat(x, list_length, axis=1)
         elif xmin is None or xmax is None:
@@ -84,8 +83,7 @@ def prep_data(xmin, xmax, list_length):
             )
 
         else:
-            # if only a single xmin and xmax without [], repeat to fit size
-            # of y
+            # if only a single xmin and xmax without [], repeat to fit size of y
             if isinstance(xmin, (int, float)):
                 x = np.array([[xmin], [xmax]])
                 x = np.repeat(x, list_length, axis=1)
@@ -101,11 +99,13 @@ def prep_style(kwargs, list_length):
 
         # prepare labels
         if "l" in kwargs:
-            # if several lines belong to the same label, first set all to the
-            # label given via "l", then reset all entries except the first
+            # if several lines belong to the same label, first set all to None
+            # then replace first entry by the label given via "l"
             if not isinstance(kwargs["l"], list):
-                kwargs["l"] = np.repeat(kwargs["l"], list_length)
-                kwargs["l"][1:list_length] = None
+                label2use = kwargs["l"]
+                kwargs["l"] = np.repeat(None, list_length)
+                kwargs["l"][0] = label2use
+
         else:
             kwargs["l"] = np.repeat(None, list_length)
 

From 46f87023467de92dbe2e0cd6de60c39add2af316 Mon Sep 17 00:00:00 2001
From: Michael Grund <michael.grund@kit.edu>
Date: Wed, 11 Aug 2021 18:35:52 +0200
Subject: [PATCH 16/17] formatting

---
 pygmt/src/hlines.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 0c9e3153ee4..80160846859 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -74,7 +74,8 @@ def prep_data(xmin, xmax, list_length):
 
         if xmin is None and xmax is None:
             with Session() as lib:
-                # get limits from current map boundings if not given via xmin, xmax
+                # get limits from current map boundings if not given
+                # via xmin, xmax
                 x = np.array([[lib.extract_region()[0]], [lib.extract_region()[1]]])
                 x = np.repeat(x, list_length, axis=1)
         elif xmin is None or xmax is None:
@@ -83,7 +84,8 @@ def prep_data(xmin, xmax, list_length):
             )
 
         else:
-            # if only a single xmin and xmax without [], repeat to fit size of y
+            # if only a single xmin and xmax without [], repeat to fit
+            # size of y
             if isinstance(xmin, (int, float)):
                 x = np.array([[xmin], [xmax]])
                 x = np.repeat(x, list_length, axis=1)

From d493a1c1b26cfc2efada79743ca8583d5c632cfd Mon Sep 17 00:00:00 2001
From: Michael Grund <23025878+michaelgrund@users.noreply.github.com>
Date: Wed, 4 Sep 2024 09:42:50 +0200
Subject: [PATCH 17/17] Update pygmt/src/hlines.py

Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
---
 pygmt/src/hlines.py | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/pygmt/src/hlines.py b/pygmt/src/hlines.py
index 80160846859..a8d3f237272 100644
--- a/pygmt/src/hlines.py
+++ b/pygmt/src/hlines.py
@@ -73,11 +73,9 @@ def hlines(self, y=None, xmin=None, xmax=None, **kwargs):
     def prep_data(xmin, xmax, list_length):
 
         if xmin is None and xmax is None:
-            with Session() as lib:
-                # get limits from current map boundings if not given
-                # via xmin, xmax
-                x = np.array([[lib.extract_region()[0]], [lib.extract_region()[1]]])
-                x = np.repeat(x, list_length, axis=1)
+            # get limits from current map boundings if not given via xmin, xmax
+            xmin, xmax = fig.region[0:2]
+            x = np.repeat([[xmin], [xmax]], list_length, axis=1)
         elif xmin is None or xmax is None:
             raise GMTInvalidInput(
                 "Must provide both, xmin and xmax if limits are not set automatically."