Consolidate scale inference.

leather/__init__.py

@@ -1,12 +1,12 @@
 #!/usr/bin/env python
 
 from leather.axis import Axis
+from leather.data_types import Number, Text
 from leather.chart import Chart
 from leather.grid import Grid
 from leather.lattice import Lattice
 from leather.legend import Legend
-from leather.scales.linear import LinearScale
-from leather.scales.ordinal import OrdinalScale
+from leather.scales import Linear, Ordinal
 from leather.shapes.columns import Columns
 from leather.shapes.dots import Dots
 from leather.shapes.lines import Lines

leather/chart.py

@@ -6,9 +6,7 @@
 import six
 
 from leather.axis import Axis
-from leather.data_types import Number, Text
-from leather.scales.linear import LinearScale
-from leather.scales.ordinal import OrdinalScale
+from leather.scales import Scale
 from leather.series import Series
 from leather.shapes.bars import Bars
 from leather.shapes.columns import Columns
@@ -69,7 +67,7 @@ def set_y_axis(self, axis):
         """
         self._set_axis(Y, axis)
 
-    def add_series(self, series, shape):
+    def add_series(self, series):
         """
         Add a data :class:`.Series` to the chart.
         """
@@ -79,31 +77,31 @@ def add_series(self, series, shape):
             elif series.types[dim] is not self._types[dim]:
                 raise TypeError('Can\'t mix axis-data types: %s and %s' % (series.types[dim], self._types[dim]))
 
-        self._layers.append((series, shape))
+        self._layers.append(series)
 
     def add_bars(self, data, name=None):
         """
         Shortcut method for adding a bar series to the chart.
         """
-        self.add_series(Series(data, name=name), DEFAULT_BARS)
+        self.add_series(Series(data, DEFAULT_BARS, name=name))
 
     def add_columns(self, data, name=None):
         """
         Shortcut method for adding a column series to the chart.
         """
-        self.add_series(Series(data, name=name), DEFAULT_COLUMNS)
+        self.add_series(Series(data, DEFAULT_COLUMNS, name=name))
 
     def add_dots(self, data, name=None):
         """
         Shortcut method for adding a dotted series to the chart.
         """
-        self.add_series(Series(data, name=name), DEFAULT_DOTS)
+        self.add_series(Series(data, DEFAULT_DOTS, name=name))
 
     def add_lines(self, data, name=None):
         """
         Shortcut method for adding a line series to the chart.
         """
-        self.add_series(Series(data, name=name), DEFAULT_LINES)
+        self.add_series(Series(data, DEFAULT_LINES, name=name))
 
     def _validate_dimension(self, dimension):
         """
@@ -117,25 +115,7 @@ def _validate_dimension(self, dimension):
 
         if not axis:
             if not scale:
-                # Default Number scale is Linear
-                if data_type is Number:
-                    data_min = min([series.min(dimension) for series, shape in self._layers])
-                    data_max = max([series.max(dimension) for series, shape in self._layers])
-
-                    scale = LinearScale(data_min, data_max)
-                # Default Text scale is Ordinal
-                elif data_type is Text:
-                    scale_values = None
-
-                    for series, shape in self._layers:
-                        if not scale_values:
-                            scale_values = series.values(dimension)
-                            continue
-
-                        if series.values(dimension) != scale_values:
-                            raise ValueError('Mismatched series scales')
-
-                    scale = OrdinalScale(scale_values)
+                scale = Scale.infer(self._layers, dimension, data_type)
             else:
                 scale = scale
 
@@ -189,8 +169,8 @@ def to_svg_group(self, width, height, margin=None):
         # Series
         series_group = ET.Element('g')
 
-        for series, shape in self._layers:
-            series_group.append(shape.to_svg(canvas_width, canvas_height, x_scale, y_scale, series))
+        for series in self._layers:
+            series_group.append(series.to_svg(canvas_width, canvas_height, x_scale, y_scale))
 
         root_group.append(axes_group)
         root_group.append(series_group)

leather/data_types.py

@@ -4,9 +4,6 @@
 
 import six
 
-from leather.scales.linear import LinearScale
-from leather.scales.ordinal import OrdinalScale
-
 
 class DataType(object):
     """

leather/lattice.py

@@ -1,10 +1,8 @@
 #!/usr/bin/env python
 
 from leather.chart import Chart
-from leather.data_types import Number, Text
 from leather.grid import Grid
-from leather.scales.linear import LinearScale
-from leather.scales.ordinal import OrdinalScale
+from leather.scales import Scale
 from leather.series import Series
 from leather.utils import X, Y
 
@@ -22,35 +20,14 @@ def __init__(self, data, shape):
 
     def _validate_dimension(self, dimension, chart_series):
         scale = None
-        axis = None
 
         data_type = chart_series[0].types[dimension]
 
         for series in chart_series[1:]:
             if series.types[dimension] is not data_type:
                 raise TypeError('All series must have the same data types.')
 
-        # Default Number scale is Linear
-        if data_type is Number:
-            data_min = min([series.min(dimension) for series in chart_series])
-            data_max = max([series.max(dimension) for series in chart_series])
-
-            scale = LinearScale(data_min, data_max)
-        # Default Text scale is Ordinal
-        elif data_type is Text:
-            scale_values = None
-
-            for series in chart_series:
-                if not scale_values:
-                    scale_values = series.values(dimension)
-                    continue
-
-                if series.values(dimension) != scale_values:
-                    raise ValueError('Mismatched series scales')
-
-            scale = OrdinalScale(scale_values)
-
-        return (scale, axis)
+        return Scale.infer(chart_series, dimension, data_type)
 
     def to_svg(self, path, width=1200, height=1200):
         """
@@ -59,20 +36,18 @@ def to_svg(self, path, width=1200, height=1200):
         chart_series = []
 
         for seq in self._data:
-            chart_series.append(Series(seq))
+            chart_series.append(Series(seq, self._shape))
 
-        x_scale, x_axis = self._validate_dimension(X, chart_series)
-        y_scale, y_axis = self._validate_dimension(Y, chart_series)
+        x_scale = self._validate_dimension(X, chart_series)
+        y_scale = self._validate_dimension(Y, chart_series)
 
         grid = Grid()
 
         for series in chart_series:
             chart = Chart()
             chart.set_x_scale(x_scale)
             chart.set_y_scale(y_scale)
-            chart.set_x_axis(x_axis)
-            chart.set_y_axis(y_axis)
-            chart.add_series(series, self._shape)
+            chart.add_series(series)
 
             grid.add_chart(chart)
 

leather/scales/__init__.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+from leather.scales.base import Scale
+from leather.scales.linear import Linear
+from leather.scales.ordinal import Ordinal

leather/scales/base.py

@@ -1,9 +1,63 @@
 #!/usr/bin/env python
 
+from leather.data_types import Number, Text
+from leather.shapes import Bars, Columns
+
+
 class Scale(object):
     """
     Base class for various kinds of scale objects.
     """
+    @classmethod
+    def infer(cls, series_list, dimension, data_type):
+        """
+        Infer's an appropriate default scale for a given sequence of series.
+
+        :param chart_series:
+            A sequence of :code:`(series, shape)` pairs.
+        :param dimension:
+            The dimension, :code:`X` or :code:`Y` of the data to infer for.
+        """
+        from leather.scales.linear import Linear
+        from leather.scales.ordinal import Ordinal
+
+        # Default Number scale is Linear
+        if data_type is Number:
+            force_zero = False
+            data_min = 0
+            data_max = 0
+
+            for series in series_list:
+                if isinstance(series.shape, (Bars, Columns)):
+                    force_zero = True
+
+                data_min = min(data_min, series.min(dimension))
+                data_max = max(data_max, series.max(dimension))
+
+            if force_zero:
+                if data_min > 0:
+                    data_min = 0
+
+                if data_max < 0:
+                    data_max = 0
+
+            scale = Linear(data_min, data_max)
+        # Default Text scale is Ordinal
+        elif data_type is Text:
+            scale_values = None
+
+            for series in series_list:
+                if not scale_values:
+                    scale_values = series.values(dimension)
+                    continue
+
+                if series.values(dimension) != scale_values:
+                    raise ValueError('Mismatched series scales')
+
+            scale = Ordinal(scale_values)
+
+        return scale
+
     def project(self, value, target_range):
         raise NotImplementedError
 

leather/scales/linear.py

@@ -2,7 +2,8 @@
 
 from leather.scales.base import Scale
 
-class LinearScale(Scale):
+
+class Linear(Scale):
     """
     A scale that linearly maps values from a domain to a range.
     """

leather/scales/ordinal.py

@@ -2,7 +2,7 @@
 
 from leather.scales.base import Scale
 
-class OrdinalScale(Scale):
+class Ordinal(Scale):
     """
     A scale that maps individual values to a range.
     """

leather/series.py

@@ -14,8 +14,9 @@ class Series(object):
     :param name:
         An optional name to be used in labeling this series.
     """
-    def __init__(self, data, name=None):
+    def __init__(self, data, shape, name=None):
         self.data = data
+        self.shape = shape
         self.name = name
 
         self.types = [None, None]
@@ -48,3 +49,9 @@ def max(self, dimension):
         Compute the minimum value of a given dimension.
         """
         return max(self.values(dimension))
+
+    def to_svg(self, width, height, x_scale, y_scale):
+        """
+        Render this series to SVG elements using it's assigned shape.
+        """
+        return self.shape.to_svg(width, height, x_scale, y_scale, self)

leather/shapes/__init__.py

@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+
+from leather.shapes.base import Shape
+from leather.shapes.bars import Bars
+from leather.shapes.columns import Columns
+from leather.shapes.dots import Dots
+from leather.shapes.lines import Lines

test.py

@@ -64,42 +64,42 @@
 #
 # grid.to_svg('test.svg', 1200, 600)
 
-# 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.Line())
-#
-# lattice.to_svg('test.svg', 1200, 600)
+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())
 
-data = [
-    (3, 'foo'),
-    (5, 'bing'),
-    (9, 'baz'),
-    (4, 'blurg')
-]
+lattice.to_svg('test.svg', 1200, 600)
 
-chart = leather.Chart()
-chart.add_bars(data)
-chart.to_svg('test.svg')
+# data = [
+#     (3, 'foo'),
+#     (5, 'bing'),
+#     (9, 'baz'),
+#     (4, 'blurg')
+# ]
+#
+# chart = leather.Chart()
+# chart.add_bars(data)
+# chart.to_svg('test.svg')