hotfix for pandas 0.25.0 update, closes #245 (#246)

* hotfix for pandas 0.25.0 update, closes #245

* added note of origin

* stickler caught a live one!

pyam/_style.py

@@ -0,0 +1,102 @@
+#
+# This file is taken from https://github.com/pandas-dev/pandas as suggested by
+# the pandas-dev mailing list. The goal is to ask the matplotlib devs to
+# eventually incorporate this into matplotlib proper.
+#
+
+# being a bit too dynamic
+import warnings
+
+import matplotlib.cm as cm
+import matplotlib.colors
+import numpy as np
+
+from pandas.core.dtypes.common import is_list_like
+
+import pandas.core.common as com
+
+
+def _get_standard_colors(
+    num_colors=None, colormap=None, color_type="default", color=None
+):
+    import matplotlib.pyplot as plt
+
+    if color is None and colormap is not None:
+        if isinstance(colormap, str):
+            cmap = colormap
+            colormap = cm.get_cmap(colormap)
+            if colormap is None:
+                raise ValueError("Colormap {0} is not recognized".format(cmap))
+        colors = [colormap(num) for num in np.linspace(0, 1, num=num_colors)]
+    elif color is not None:
+        if colormap is not None:
+            warnings.warn(
+                "'color' and 'colormap' cannot be used " +
+                "simultaneously. Using 'color'"
+            )
+        colors = list(color) if is_list_like(color) else color
+    else:
+        if color_type == "default":
+            # need to call list() on the result to copy so we don't
+            # modify the global rcParams below
+            try:
+                colors = [c["color"]
+                          for c in list(plt.rcParams["axes.prop_cycle"])]
+            except KeyError:
+                colors = list(plt.rcParams.get(
+                    "axes.color_cycle", list("bgrcmyk")))
+            if isinstance(colors, str):
+                colors = list(colors)
+
+            colors = colors[0:num_colors]
+        elif color_type == "random":
+
+            def random_color(column):
+                """ Returns a random color represented as a list of length 3"""
+                # GH17525 use common._random_state to avoid resetting the seed
+                rs = com.random_state(column)
+                return rs.rand(3).tolist()
+
+            colors = [random_color(num) for num in range(num_colors)]
+        else:
+            raise ValueError("color_type must be either 'default' or 'random'")
+
+    if isinstance(colors, str):
+        conv = matplotlib.colors.ColorConverter()
+
+        def _maybe_valid_colors(colors):
+            try:
+                [conv.to_rgba(c) for c in colors]
+                return True
+            except ValueError:
+                return False
+
+        # check whether the string can be convertible to single color
+        maybe_single_color = _maybe_valid_colors([colors])
+        # check whether each character can be convertible to colors
+        maybe_color_cycle = _maybe_valid_colors(list(colors))
+        if maybe_single_color and maybe_color_cycle and len(colors) > 1:
+            hex_color = [c["color"]
+                         for c in list(plt.rcParams["axes.prop_cycle"])]
+            colors = [hex_color[int(colors[1])]]
+        elif maybe_single_color:
+            colors = [colors]
+        else:
+            # ``colors`` is regarded as color cycle.
+            # mpl will raise error any of them is invalid
+            pass
+
+    # Append more colors by cycling if there is not enough color.
+    # Extra colors will be ignored by matplotlib if there are more colors
+    # than needed and nothing needs to be done here.
+    if len(colors) < num_colors:
+        try:
+            multiple = num_colors // len(colors) - 1
+        except ZeroDivisionError:
+            raise ValueError("Invalid color argument: ''")
+        mod = num_colors % len(colors)
+
+        colors += multiple * colors
+        colors += colors[:mod]
+
+    return colors

pyam/plotting.py

@@ -33,8 +33,10 @@
 from pyam.logger import logger
 from pyam.run_control import run_control
 from pyam.utils import requires_package, IAMC_IDX, SORT_IDX, isstr
-
-from pandas.plotting._style import _get_standard_colors
+# TODO: this is a hotfix for changes in pandas 0.25.0, per discussions on the
+# pandas-dev listserv, we should try to ask if matplotlib would make it a
+# standard feature in their library
+from pyam._style import _get_standard_colors
 
 # line colors, markers, and styles that are cycled through when not
 # explicitly declared