Document interpolation and add a larger stroke width on active

demo/moulinrouge/__init__.py

@@ -98,7 +98,11 @@ def create_app():
 
     @app.route("/svg/<type>/<series>/<config>")
     def svg(type, series, config):
-        graph = getattr(pygal, type)(pickle.loads(b64decode(str(config))))
+        module = '.'.join(type.split('.')[:-1])
+        name = type.split('.')[-1]
+        from importlib import import_module
+        graph = getattr(import_module(module), name)(
+            pickle.loads(b64decode(str(config))))
         for title, values in pickle.loads(b64decode(str(series))):
             graph.add(title, values)
         return graph.render_response()
@@ -196,10 +200,13 @@ def create_app():
         config.human_readable = True
         config.interpolate = interpolate
         config.style = style
-        config.x_labels = [random_label() for i in range(data)]
         svgs = []
         for chart in pygal.CHARTS:
-            type = chart.__name__
+            type = '.'.join((chart.__module__, chart.__name__))
+            if chart._dual:
+                config.x_labels = None
+            else:
+                config.x_labels = [random_label() for i in range(data)]
             svgs.append({'type': type,
                          'series': xy_series if type == 'XY' else other_series,
                          'config': b64encode(pickle.dumps(config))})

pygal/_compat.py

@@ -16,6 +16,10 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with pygal. If not, see <http://www.gnu.org/licenses/>.
+"""
+Various hacks for transparent python 2 / python 3 support
+"""
+
 import sys
 from collections import Iterable
 import time

pygal/adapters.py

@@ -24,6 +24,7 @@ from decimal import Decimal
 
 
 def positive(x):
+    """Return zero if value is negative"""
     if x is None:
         return
     if x < 0:
@@ -32,16 +33,21 @@ def positive(x):
 
 
 def not_zero(x):
+    """Return None if value is zero"""
     if x == 0:
         return
     return x
 
 
 def none_to_zero(x):
-    return x or 0
+    """Return 0 if value is None"""
+    if x is None:
+        return 0
+    return x
 
 
 def decimal_to_float(x):
+    """Cast Decimal values to float"""
     if isinstance(x, Decimal):
         return float(x)
     return x

pygal/colors.py

@@ -150,6 +150,7 @@ _clamp = lambda x: max(0, min(100, x))
 
 
 def _adjust(hsl, attribute, percent):
+    """Internal adjust function"""
     hsl = list(hsl)
     if attribute > 0:
         hsl[attribute] = _clamp(hsl[attribute] + percent)

pygal/css/style.css

@@ -97,6 +97,7 @@
 {{ id }}.reactive.active,
 {{ id }}.active .reactive {
   fill-opacity:  {{ style.opacity_hover }};
+  stroke-width: 4;
 }
 
 {{ id }}.series text {

pygal/etree.py

@@ -16,10 +16,17 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with pygal. If not, see <http://www.gnu.org/licenses/>.
+"""
+Wrapper for seemless lxml.etree / xml.etree usage
+depending on whether lxml is installed or not.
+"""
+
 import os
 
 
 class Etree(object):
+    """Etree wrapper using lxml.etree or standard xml.etree"""
+
     def __init__(self):
         from xml.etree import ElementTree as _py_etree
         self._py_etree = _py_etree
@@ -42,10 +49,12 @@ class Etree(object):
         return object.__getattribute__(self, attr)
 
     def to_lxml(self):
+        """Force lxml.etree to be used"""
         self._etree = self._lxml_etree
         self.lxml = True
 
     def to_etree(self):
+        """Force xml.etree to be used"""
         self._etree = self._py_etree
         self.lxml = False
 

pygal/interpolate.py

@@ -17,7 +17,11 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with pygal. If not, see <http://www.gnu.org/licenses/>.
 """
-Interpolation
+Interpolation functions
+
+These functions takes two lists of points x and y and
+returns an iterator over the interpolation between all these points
+with `precision` interpolated points between each of them
 
 """
 from __future__ import division
@@ -25,6 +29,11 @@ from math import sin
 
 
 def quadratic_interpolate(x, y, precision=250, **kwargs):
+    """
+    Interpolate x, y using a quadratic algorithm
+    https://en.wikipedia.org/wiki/Spline_(mathematics)
+    """
+
     n = len(x) - 1
     delta_x = [x2 - x1 for x1, x2 in zip(x, x[1:])]
     delta_y = [y2 - y1 for y1, y2 in zip(y, y[1:])]
@@ -51,6 +60,10 @@ def quadratic_interpolate(x, y, precision=250, **kwargs):
 
 
 def cubic_interpolate(x, y, precision=250, **kwargs):
+    """
+    Interpolate x, y using a cubic algorithm
+    https://en.wikipedia.org/wiki/Spline_interpolation
+    """
     n = len(x) - 1
     # Spline equation is a + bx + cx² + dx³
     # ie: Spline part i equation is a[i] + b[i]x + c[i]x² + d[i]x³
@@ -91,6 +104,25 @@ def cubic_interpolate(x, y, precision=250, **kwargs):
 
 def hermite_interpolate(x, y, precision=250,
                         type='cardinal', c=None, b=None, t=None):
+    """
+    Interpolate x, y using the hermite method.
+    See https://en.wikipedia.org/wiki/Cubic_Hermite_spline
+
+    This interpolation is configurable and contain 4 subtypes:
+      * Catmull Rom
+      * Finite Difference
+      * Cardinal
+      * Kochanek Bartels
+
+    The cardinal subtype is customizable with a parameter:
+      * c: tension (0, 1)
+
+    This last type is also customizable using 3 parameters:
+      * c: continuity (-1, 1)
+      * b: bias       (-1, 1)
+      * t: tension    (-1, 1)
+
+    """
     n = len(x) - 1
     m = [1] * (n + 1)
     w = [1] * (n + 1)
@@ -148,6 +180,10 @@ def hermite_interpolate(x, y, precision=250,
 
 
 def lagrange_interpolate(x, y, precision=250, **kwargs):
+    """
+    Interpolate x, y using Lagrange polynomials
+    https://en.wikipedia.org/wiki/Lagrange_polynomial
+    """
     n = len(x) - 1
     delta_x = [x2 - x1 for x1, x2 in zip(x, x[1:])]
     for i in range(n + 1):
@@ -170,7 +206,10 @@ def lagrange_interpolate(x, y, precision=250, **kwargs):
 
 
 def trigonometric_interpolate(x, y, precision=250, **kwargs):
-    """As per http://en.wikipedia.org/wiki/Trigonometric_interpolation"""
+    """
+    Interpolate x, y using trigonometric
+    As per http://en.wikipedia.org/wiki/Trigonometric_interpolation
+    """
     n = len(x) - 1
     delta_x = [x2 - x1 for x1, x2 in zip(x, x[1:])]
     for i in range(n + 1):
@@ -191,12 +230,6 @@ def trigonometric_interpolate(x, y, precision=250, **kwargs):
                 s += y[k] * p
             yield X, s
 
-"""
-These functions takes two lists of points x and y and
-returns an iterator over the interpolation between all these points
-with `precision` interpolated points between each of them
-
-"""
 INTERPOLATIONS = {
     'quadratic': quadratic_interpolate,
     'cubic': cubic_interpolate,
@@ -213,4 +246,18 @@ if __name__ == '__main__':
     xy.add('normal', points)
     xy.add('quadratic', quadratic_interpolate(*zip(*points)))
     xy.add('cubic', cubic_interpolate(*zip(*points)))
+    xy.add('lagrange', lagrange_interpolate(*zip(*points)))
+    xy.add('trigonometric', trigonometric_interpolate(*zip(*points)))
+    xy.add('hermite catmul_rom', hermite_interpolate(
+        *zip(*points), type='catmul_rom'))
+    xy.add('hermite finite_difference', hermite_interpolate(
+        *zip(*points), type='finite_difference'))
+    xy.add('hermite cardinal -.5', hermite_interpolate(
+        *zip(*points), type='cardinal', c=-.5))
+    xy.add('hermite cardinal .5', hermite_interpolate(
+        *zip(*points), type='cardinal', c=.5))
+    xy.add('hermite kochanek_bartels .5 .75 -.25', hermite_interpolate(
+        *zip(*points), type='kochanek_bartels', c=.5, b=.75, t=-.25))
+    xy.add('hermite kochanek_bartels .25 -.75 .5', hermite_interpolate(
+        *zip(*points), type='kochanek_bartels', c=.25, b=-.75, t=.5))
     xy.render_in_browser()