Secondary axis support

pygal/css/graph.css

@@ -49,8 +49,12 @@ text.no_data {
 .axis.y text {
   text-anchor: end;
 }
+.axis.2y text {
+  text-anchor: start;
+}
 
-.axis.y .logarithmic text:not(.major) {
+.axis.y .logarithmic text:not(.major) ,
+.axis.2y .logarithmic text:not(.major) {
   font-size: 50%;
 }
 
@@ -66,11 +70,13 @@ text.no_data {
 }
 
 .horizontal .axis.y .guide.line,
+.horizontal .axis.2y .guide.line,
 .vertical .axis.x .guide.line {
   opacity: 0;
 }
 
 .axis.y .guides:hover .guide.line,
+.axis.2y .guides:hover .guide.line,
 .line-graph .axis.x .guides:hover .guide.line,
 .gauge-graph .axis.x .guides:hover .guide.line,
 .stackedline-graph .axis.x .guides:hover .guide.line,

pygal/ghost.py

@@ -55,20 +55,25 @@ class Ghost(object):
         config(**kwargs)
         self.config = config
         self.raw_series = []
+        self.raw_series2 = []
 
-    def add(self, title, values):
+    def add(self, title, values, secondary=False):
         """Add a serie to this graph"""
         if not hasattr(values, '__iter__') and not isinstance(values, dict):
             values = [values]
+        if secondary:
+            self.raw_series2.append((title, values))
+        else:
             self.raw_series.append((title, values))
 
-    def make_series(self):
+    def make_series(self, series):
-        return prepare_values(self.raw_series, self.config, self.cls)
+        return prepare_values(series, self.config, self.cls)
 
     def make_instance(self):
         self.config(**self.__dict__)
-        series = self.make_series()
+        series = self.make_series(self.raw_series)
-        self._last__inst = self.cls(self.config, series)
+        secondary_series = self.make_series(self.raw_series2)
+        self._last__inst = self.cls(self.config, series, secondary_series)
         return self._last__inst
 
     # Rendering

pygal/graph/__init__.py

@@ -35,5 +35,6 @@ CHARTS_NAMES = [
     'Pyramid',
     'VerticalPyramid',
     'Dot',
-    'Gauge'
+    'Gauge',
+    'DoubleYLine',
 ]

pygal/graph/base.py

@@ -35,17 +35,20 @@ class BaseGraph(object):
 
     _adapters = []
 
-    def __init__(self, config, series):
+    def __init__(self, config, series, secondary_series):
         """Init the graph"""
         self.config = config
         self.series = series or []
+        self.secondary_series = secondary_series or []
         self.horizontal = getattr(self, 'horizontal', False)
         self.svg = Svg(self)
         self._x_labels = None
         self._y_labels = None
+        self._y_2nd_labels = None
         self.nodes = {}
         self.margin = Margin(*([20] * 4))
         self._box = Box()
+        self._secondary_box = Box()
         self.view = None
         if self.logarithmic and self.zero == 0:
             # Explicit min to avoid interpolation dependency
@@ -94,7 +97,7 @@ class BaseGraph(object):
         if self.show_legend and self.series:
             h, w = get_texts_box(
                 map(lambda x: truncate(x, self.truncate_legend or 15),
-                    cut(self.series, 'title')),
+                    cut(self.series + self.secondary_series, 'title')),
                 self.legend_font_size)
             if self.legend_at_bottom:
                 h_max = max(h, self.legend_box_size)
@@ -123,13 +126,19 @@ class BaseGraph(object):
             h, w = get_texts_box(
                 cut(self._y_labels), self.label_font_size)
             self.margin.left += 10 + max(
-                w * cos(rad(self.y_label_rotation)), h)
+                w * cos(rad(self.y_label_rotation)), w)
+	
 
     @cached_property
     def _legends(self):
         """Getter for series title"""
         return [serie.title for serie in self.series]
     
+    @cached_property
+    def _secondary_legends(self):
+        """Getter for series title on secondary y axis"""
+        return [serie.title for serie in self.secondary_series]
+
     @cached_property
     def _values(self):
         """Getter for series values (flattened)"""
@@ -138,10 +147,24 @@ class BaseGraph(object):
                 for val in serie.values
                 if val is not None]
 
+    @cached_property
+    def _secondary_values(self):
+        """Getter for secondary series values (flattened)"""
+        return [val
+                for serie in self.secondary_series
+                for val in serie.values
+                if val is not None]
+
     @cached_property
     def _len(self):
         """Getter for the maximum series size"""
-        return max([len(serie.values) for serie in self.series] or [0])
+        return max([len(serie.values) for serie in self.series + self.secondary_series] or [0])
+
+    @cached_property
+    def _secondary_min(self):
+        """Getter for the minimum series value"""
+        return (self.range and self.range[0]) or (
+            min(self._secondary_values) if self._secondary_values else None)
 
     @cached_property
     def _min(self):
@@ -149,16 +172,29 @@ class BaseGraph(object):
         return (self.range and self.range[0]) or (
             min(self._values) if self._values else None)
 
+    @cached_property
+    def _secondary_min(self):
+        """Getter for the secondary minimum series value"""
+        return (self.range and self.range[0]) or (
+            min(self._secondary_values) if self._secondary_values else None)
+
+
     @cached_property
     def _max(self):
         """Getter for the maximum series value"""
         return (self.range and self.range[1]) or (
             max(self._values) if self._values else None)
 
+    @cached_property
+    def _secondary_max(self):
+        """Getter for the maximum series value"""
+        return (self.range and self.range[1]) or (
+            max(self._secondary_values) if self._secondary_values else None)
+
     @cached_property
     def _order(self):
         """Getter for the maximum series value"""
-        return len(self.series)
+        return len(self.series + self.secondary_series)
 
     def _draw(self):
         """Draw all the things"""

pygal/graph/graph.py

@@ -25,8 +25,9 @@ from __future__ import division
 from pygal.interpolate import interpolation
 from pygal.graph.base import BaseGraph
 from pygal.view import View, LogView, XYLogView
-from pygal.util import is_major, truncate, reverse_text_len
+from pygal.util import is_major, truncate, reverse_text_len, get_texts_box, cut, rad
-from math import isnan, pi, sqrt, ceil
+from math import isnan, pi, sqrt, ceil, cos
+from itertools import repeat, izip, chain, count
 
 
 class Graph(BaseGraph):
@@ -60,6 +61,8 @@ class Graph(BaseGraph):
             self.height - self.margin.y,
             self._box)
 
+                           
+
     def _make_graph(self):
         """Init common graph svg structure"""
         self.nodes['graph'] = self.svg.node(
@@ -128,18 +131,21 @@ class Graph(BaseGraph):
             self.svg.node(axis, 'path',
                           d='M%f %f v%f' % (0, 0, self.view.height),
                           class_='line')
+        lastlabel = self._x_labels[-1][0]
         for label, position in self._x_labels:
             major = is_major(position)
             guides = self.svg.node(axis, class_='guides')
             x = self.view.x(position)
             y = self.view.height + 5
             if draw_axes:
+                last_guide = (self._y_2nd_labels and label == lastlabel)
                 self.svg.node(
                     guides, 'path',
                     d='M%f %f v%f' % (x, 0, self.view.height),
                     class_='%s%sline' % (
                         'major ' if major else '',
-                        'guide ' if position != 0 else ''))
+                        'guide ' if position != 0 and not last_guide
+                                 else ''))
             y += .5 * self.label_font_size + 5
             text = self.svg.node(
                 guides, 'text',
@@ -192,6 +198,37 @@ class Graph(BaseGraph):
                 text.attrib['transform'] = "rotate(%d %f %f)" % (
                     self.y_label_rotation, x, y)
 
+        # TODO: 
+        # - shall we do separate axis 2y node, or use the above (and have an inner
+        #       loop condition)
+        # - it 
+        # 10 is a magic number around here - margin size, don't know, 
+        # what stands for the additional 2 px
+        if self._y_2nd_labels:
+                secondary_ax = self.svg.node(self.nodes['plot'], class_="axis 2y")
+                #self.svg.node(secondary_ax, 'path',
+                #    d='M%f %f v%f' % (self.view.width-12, 0, self.view.height),
+                #    class_='major line'
+                #)
+                for label, position in self._y_2nd_labels:
+                    major = is_major(position)
+                    # it is needed, to have the same structure
+                    guides = self.svg.node(secondary_ax, class_='guides')
+                    x = self.view.width + 5
+                    y = self.view.y(position)
+                    text = self.svg.node(guides, 'text',
+                        x = x,
+                        # XXX: plus or minus?
+                        y = y + .35 * self.label_font_size,
+                        class_ = 'major' if major else ''
+                    )
+                    text.text = label
+                    if self.y_label_rotation:
+                        text.attrib['transform'] = "rotate(%d %f %f)" % (
+                            self.y_label_rotation, x, y)
+
+            
+
     def _legend(self):
         """Make the legend box"""
         if not self.show_legend:
@@ -209,7 +246,15 @@ class Graph(BaseGraph):
                 truncation = reverse_text_len(
                     available_space, self.legend_font_size)
         else:
-            x = self.margin.left + self.view.width + 10
+            # draw primary y axis on left
+            x = 0
+            h, w = get_texts_box(
+                cut(self._y_labels), self.label_font_size)
+            #x -= 10 + max(w * cos(rad(self.y_label_rotation)), h)
+            x -= 10 + w
+            h, w = get_texts_box(self._legends + self._secondary_legends, self.label_font_size)
+            x -= w
+
             y = self.margin.top + 10
             cols = 1
             if not truncation:
@@ -219,15 +264,44 @@ class Graph(BaseGraph):
             self.nodes['graph'], class_='legends',
             transform='translate(%d, %d)' % (x, y))
 
+
         h = max(self.legend_box_size, self.legend_font_size)
         x_step = self.view.width / cols
-        for i, title in enumerate(self._legends):
+        if self.legend_at_bottom:
+            # if legends at the bottom, we dont split the windows
+            counter = count()
+            # gen structure - (i, (j, (l, tf)))
+            gen = enumerate(enumerate(chain(
+                    izip(self._legends, repeat(False)),
+                    izip(self._secondary_legends, repeat(True)))))
+            secondary_legends = legends
+        else:
+            gen = enumerate(chain(
+                    enumerate(izip(self._legends, repeat(False))),
+                    enumerate(izip(self._secondary_legends, repeat(True)))))
+
+            # draw secondary axis on right
+            x = self.margin.left + self.view.width + 10
+            if self._y_2nd_labels:
+                    h, w = get_texts_box(
+                        cut(self._y_labels), self.label_font_size)
+                    x += 10 + max(w * cos(rad(self.y_label_rotation)), h)
+
+            y = self.margin.top + 10
+
+            secondary_legends = self.svg.node(
+                self.nodes['graph'], class_='legends',
+                transform='translate(%d, %d)' % (x, y))
+            
+        for (global_serie_number, (i, (title, is_secondary))) in gen:
+                
             col = i % cols
             row = i // cols
 
             legend = self.svg.node(
-                legends, class_='legend reactive activate-serie',
+                secondary_legends if is_secondary else legends,
-                id="activate-serie-%d" % i)
+                class_='legend reactive activate-serie',
+                id="activate-serie-%d" % global_serie_number)
             self.svg.node(
                 legend, 'rect',
                 x=col * x_step,
@@ -237,7 +311,7 @@ class Graph(BaseGraph):
                 ) / 2,
                 width=self.legend_box_size,
                 height=self.legend_box_size,
-                class_="color-%d reactive" % (i % 16)
+                class_="color-%d reactive" % (global_serie_number % 16)
             )
             truncated = truncate(title, truncation)
             # Serious magical numbers here
@@ -327,7 +401,7 @@ class Graph(BaseGraph):
         return self._format(values[i][1])
 
     def _points(self, x_pos):
-        for serie in self.series:
+        for serie in self.series + self.secondary_series:
             serie.points = [
                 (x_pos[i], v)
                 for i, v in enumerate(serie.values)]

pygal/util.py

@@ -143,12 +143,21 @@ def compute_logarithmic_scale(min_, max_, min_scale, max_scale):
 
 def compute_scale(
         min_, max_, logarithmic=False, order_min=None,
-        min_scale=4, max_scale=20):
+        min_scale=4, max_scale=20, force_steps=None):
     """Compute an optimal scale between min and max"""
     if min_ == 0 and max_ == 0:
         return [0]
     if max_ - min_ == 0:
         return [min_]
+    if force_steps:
+        # TODO: handle logarithmic scale
+        step = float(max_ - min_) / (force_steps - 1)
+        curr = min_
+        ret = []
+        for i in range(force_steps):
+                ret.append(curr)
+                curr += step
+        return ret
     if logarithmic:
         log_scale = compute_logarithmic_scale(
             min_, max_, min_scale, max_scale)