Fix negative bars

demo/moulinrouge/__init__.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 from flask import Flask, Response, render_template, url_for
 from log_colorizer import make_colored_stream_handler
-from logging import getLogger, INFO, WARN, DEBUG
+from logging import getLogger, INFO, DEBUG
 from moulinrouge.data import labels, series
 # from pygal.bar import VerticalBar, HorizontalBar
 from pygal.line import Line
@@ -9,7 +9,6 @@ from pygal.bar import Bar
 from pygal.config import Config
 from pygal.style import styles
 # from pygal.pie import Pie
-import math
 import string
 import random
 
@@ -73,7 +72,8 @@ def create_app():
             return
 
         for i in range(random.randrange(1, 10)):
-            values = [random_value(min, max) for i in range(data)]
+            values = [random_value((-max, min)[random.randrange(0, 2)],
+                                   max) for i in range(data)]
             g.add(random_label(), values)
 
         return Response(g.render(), mimetype='image/svg+xml')

pygal/bar.py

@@ -6,7 +6,7 @@ class Bar(BaseGraph):
 
     def _draw(self):
         vals = [val for serie in self.series for val in serie.values]
-        ymin, ymax = min(min(vals), 0), max(vals)
+        ymin, ymax = min(min(vals), 0), max(max(vals), 0)
         x_step = len(self.series[0].values)
         x_pos = [x / float(x_step) for x in range(x_step + 1)
         ] if x_step > 1 else [0, 1]  # Center if only one value

pygal/base.py

@@ -20,13 +20,16 @@ class BaseGraph(object):
         return object.__getattribute__(self, attr)
 
     def _y_pos(self, ymin, ymax):
-        order = round(math.log10(ymax)) - 1
+        order = round(math.log10(max(abs(ymin), abs(ymax)))) - 1
         if (ymax - ymin) / float(10 ** order) < 4:
             order -= 1
         step = 10 ** order
         positions = set()
-        position = round_to_scale(ymin, step)
-        while position < ymax:
+        if self.x_start_at_zero:
+            position = 0
+        else:
+            position = round_to_scale(ymin, step)
+        while position < (ymax + step):
             rounded = round_to_scale(position, self.scale)
             if ymin <= rounded <= ymax:
                 positions.add(rounded)

pygal/config.py

@@ -12,6 +12,7 @@ class Config(object):
     x_labels = None
     y_labels = None
     title = None
+    x_start_at_zero = False
 
     def __init__(self, **kwargs):
         self.__dict__.update(kwargs)

pygal/svg.py

@@ -164,11 +164,15 @@ class Svg(object):
             bar_padding = .1 * bar_width
             bar_inner_width = bar_width - 2 * bar_padding
             offset = serie.index * bar_width + bar_padding
+            height = self.view.y(0) - y
+            if height < 0:
+                y = y + height
+                height = -height
             self.node(serie_node, 'rect',
                       x=x + padding + offset,
                       y=y,
                       width=bar_inner_width,
-                      height=self.view.y(0) - y,
+                      height=height,
                       class_='rect')
 
     def render(self):

pygal/test/test_bar.py

@@ -4,8 +4,9 @@ from math import cos, sin
 
 def test_simple_bar():
     bar = Bar()
-    rng = [12, 3, 30, -5, 40, 10, 9, 2]
+    rng = [-3, -32, -39]
     bar.add('test1', rng)
+    bar.add('test2', map(abs, rng))
     bar.x_labels = map(str, rng)
     bar.title = "Bar test"
     bar._in_browser()

pygal/test/test_line.py

@@ -4,7 +4,7 @@ from math import cos, sin
 
 
 def test_simple_line():
-    line = Line(Config(scale=.5))
+    line = Line(Config(scale=.0005))
     rng = range(-30, 31, 5)
     line.add('test1', [cos(x / 10.) for x in rng])
     line.add('test2', [sin(x / 10.) for x in rng])