Add rough timescale support. Closes #14.

docs/api/scales.rst

@@ -10,3 +10,5 @@ Scales
 .. autoclass:: leather.Linear
 
 .. autoclass:: leather.Ordinal
+
+.. autoclass:: leather.Temporal

leather/data_types.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 
+from datetime import date, datetime
 from decimal import Decimal
 
 import six
@@ -11,14 +12,27 @@ class DataType(object):
     """
     @classmethod
     def infer(cls, v):
-        if isinstance(v, Number.types):
-            return Number
-        elif isinstance(v, Text.types):
-            return Text
+        for t in [DateTime, Date, Number, Text]:
+            if isinstance(v, t.types):
+                return t
 
         raise TypeError('No data type available for %s' % type(v))
 
 
+class Date(DataType):
+    """
+    Data representing dates.
+    """
+    types = (date,)
+
+
+class DateTime(DataType):
+    """
+    Data representing dates with times.
+    """
+    types = (datetime,)
+
+
 class Number(DataType):
     """
     Data representing numbers.

leather/scales/__init__.py

@@ -3,3 +3,4 @@
 from leather.scales.base import Scale
 from leather.scales.linear import Linear
 from leather.scales.ordinal import Ordinal
+from leather.scales.temporal import Temporal

leather/scales/base.py

@@ -1,6 +1,8 @@
 #!/usr/bin/env python
 
-from leather.data_types import Number, Text
+from datetime import date, datetime
+
+from leather.data_types import Date, DateTime, Number, Text
 from leather.shapes import Bars, Columns
 
 
@@ -23,9 +25,30 @@ def infer(cls, series_list, dimension, data_type):
         """
         from leather.scales.linear import Linear
         from leather.scales.ordinal import Ordinal
+        from leather.scales.temporal import Temporal
+
+        # Default Time scale is Temporal
+        # Default Time scale is Temporal
+        if data_type is Date:
+            data_min = date.max
+            data_max = date.min
+
+            for series in series_list:
+                data_min = min(data_min, series.min(dimension))
+                data_max = max(data_max, series.max(dimension))
+
+            scale = Temporal(data_min, data_max)
+        elif data_type is DateTime:
+            data_min = datetime.max
+            data_max = datetime.min
+
+            for series in series_list:
+                data_min = min(data_min, series.min(dimension))
+                data_max = max(data_max, series.max(dimension))
 
+            scale = Temporal(data_min, data_max)
         # Default Number scale is Linear
-        if data_type is Number:
+        elif data_type is Number:
             force_zero = False
             data_min = 0
             data_max = 0

leather/scales/temporal.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python
+
+from datetime import date, datetime, time
+
+from leather.scales.base import Scale
+
+
+class Temporal(Scale):
+    """
+    A scale that linearly maps date/datetime values from a domain to a range.
+
+    :param domain_min:
+        The minimum date/datetime of the input domain.
+    :param domain_max:
+        The maximum date/datetime of the input domain.
+    """
+    def __init__(self, domain_min, domain_max):
+        self._min = domain_min
+        self._max = domain_max
+
+    def project(self, value, range_min, range_max):
+        """
+        Project a value in this scale's domain to a target range.
+        """
+        pos = (value - self._min) / (self._max - self._min)
+
+        return ((range_max - range_min) * pos) + range_min
+
+    def project_interval(self, value, range_min, range_max):
+        """
+        Project a value in this scale's domain to an interval in the target
+        range. This is used for places :class:`.Bars` and :class:`.Columns`.
+        """
+        raise NotImplementedError
+
+    def ticks(self, count):
+        """
+        Generate a series of ticks for this scale.
+        """
+        size = (self._max - self._min) / (count - 1)
+
+        return [self._min + (size * i) for i in range(count)]

test.py

@@ -1,136 +1,18 @@
 #!/usr/bin/env python
 
-import random
+from datetime import date, datetime
 
 import leather
 
-dot_data = [(random.randint(0, 250), random.randint(0, 250)) for i in range(100)]
 
-def colorizer(x, y, i):
-    return 'rgb(%i, %i, %i)' % (x, y, 150)
+data = [
+    (datetime(2010, 1, 1), 4),
+    (datetime(2011, 5, 4), 3),
+    (datetime(2012, 6, 1, 11), 5),
+    (datetime(2013, 1, 1), 6),
+    (datetime(2014, 12, 1), 10)
+]
 
-chart = leather.Chart('Well that was easy')
-chart.add_dots(dot_data, color=colorizer)
+chart = leather.Chart("X axis ftw")
+chart.add_lines(data)
 chart.to_svg('test.svg')
-
-# dot_data = [
-#     (0, 3),
-#     (4, 5),
-#     (7, 9),
-#     (8, 4)
-# ]
-#
-# line_data = [
-#     (0, 4),
-#     (1, 3),
-#     (2, 5),
-#     (5, 6),
-#     (9, 10)
-# ]
-#
-# chart = leather.Chart()
-# # chart.set_x_scale(leather.Linear(0, 20))
-# chart.add_dots(dot_data)
-# chart.add_lines(line_data)
-# chart.to_svg('test.svg')
-
-# bar_data = [
-#     (3, 'foo'),
-#     (5, 'bing blaarg murg'),
-#     (9, 'baz'),
-#     (4, 'blurg')
-# ]
-#
-# def colorizer(x, y, i):
-#     if y == 'baz':
-#         return 'yellow'
-#     else:
-#         return 'blue'
-#
-# chart = leather.Chart('Bar charts are fun')
-# chart.add_dots(bar_data, color=colorizer)
-# chart.to_svg('test.svg')
-#
-# data = [[
-#     (0, 3),
-#     (4, 5),
-#     (7, 9),
-#     (8, 4)
-# ], [
-#     (0, 4),
-#     (1, 3),
-#     (2, 5),
-#     (5, 6),
-#     (9, 10)
-# ],[
-#     (0, 4),
-#     (1, 3),
-#     (2, 5),
-#     (5, 6),
-#     (9, 10)
-# ]]
-#
-# grid = leather.Grid()
-#
-# chart = leather.Chart('Chart A')
-# chart.add_lines(data[0])
-# grid.add_chart(chart)
-#
-# chart = leather.Chart('Chart B')
-# chart.add_dots(data[1])
-# grid.add_chart(chart)
-#
-# chart = leather.Chart('Chart C')
-# chart.add_dots(data[2])
-# grid.add_chart(chart)
-#
-# grid.to_svg('test.svg')
-
-# data = [[
-#     (0, 3),
-#     (4, 5),
-#     (7, 9),
-#     (8, 4)
-# ], [
-#     (0, 4),
-#     (1, 3),
-#     (2, 3),
-#     (10, 7),
-#     (15, 5)
-# ], [
-#     (0, 4),
-#     (5, 5),
-#     (6, 6),
-#     (7, 7),
-#     (8, 8)
-# ], [
-#     (4, 4),
-#     (6, 3),
-#     (7, 5),
-#     (8, 6),
-#     (12, 10)
-# ]]
-#
-# lattice = leather.Lattice(data, leather.Lines('purple'), ['A', 'B', 'C', 'D'])
-#
-# lattice.to_svg('test.svg', 1200, 600)
-
-# data = [
-#     (3, 1),
-#     (5, 3),
-#     (9, 12),
-#     (4, 15)
-# ]
-#
-# chart = leather.Chart()
-# chart.add_bars(data)
-# chart.to_svg('test.svg')
-
-# chart = leather.Chart()
-# chart.set_x_scale(leather.Linear(0, 20))
-# chart.set_x_axis(leather.Axis(ticks=5))
-# chart.set_y_scale(leather.Linear(0, 20))
-# chart.set_y_axis(leather.Axis(ticks=5))
-# chart.add_dots(data)
-#
-# chart.to_svg('test.svg')