Python to generate nice looking SVG graph http://pygal.org/
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#!python
from itertools import chain
from lxml import etree
from svg.charts.graph import Graph
__all__ = ('VerticalBar', 'HorizontalBar')
class Bar(Graph):
"A superclass for bar-style graphs. Do not instantiate directly."
# gap between bars
bar_gap = True
# how to stack adjacent dataset series
# overlap - overlap bars with transparent colors
# top - stack bars on top of one another
# side - stack bars side-by-side
stack = 'overlap'
scale_divisions = None
stylesheet_names = Graph.stylesheet_names + ['bar.css']
def __init__(self, fields, *args, **kargs):
self.fields = fields
super(Bar, self).__init__(*args, **kargs)
# adapted from Plot
def get_data_values(self):
min_value, max_value, scale_division = self.data_range()
result = tuple(float_range(min_value, max_value + scale_division, scale_division))
if self.scale_integers:
result = map(int, result)
return result
# adapted from plot (very much like calling data_range('y'))
def data_range(self):
min_value = self.data_min()
max_value = self.data_max()
range = max_value - min_value
data_pad = range / 20.0 or 10
scale_range = (max_value + data_pad) - min_value
scale_division = self.scale_divisions or (scale_range / 10.0)
if self.scale_integers:
scale_division = round(scale_division) or 1
return min_value, max_value, scale_division
def get_field_labels(self):
return self.fields
def get_data_labels(self):
return map(str, self.get_data_values())
def data_max(self):
return max(chain(*map(lambda set: set['data'], self.data)))
# above is same as
# return max(map(lambda set: max(set['data']), self.data))
def data_min(self):
if not getattr(self, 'min_scale_value') is None: return self.min_scale_value
min_value = min(chain(*map(lambda set: set['data'], self.data)))
min_value = min(min_value, 0)
return min_value
def get_bar_gap(self, field_size):
bar_gap = 10 # default gap
if field_size < 10:
# adjust for narrow fields
bar_gap = field_size / 2
# the following zero's out the gap if bar_gap is False
bar_gap = int(self.bar_gap) * bar_gap
return bar_gap
def float_range(start = 0, stop = None, step = 1):
"Much like the built-in function range, but accepts floats"
while start < stop:
yield float(start)
start += step
class VerticalBar(Bar):
""" # === Create presentation quality SVG bar graphs easily
#
# = Synopsis
#
# require 'SVG/Graph/Bar'
#
# fields = %w(Jan Feb Mar);
# data_sales_02 = [12, 45, 21]
#
# graph = SVG::Graph::Bar.new(
# :height => 500,
# :width => 300,
# :fields => fields
# )
#
# graph.add_data(
# :data => data_sales_02,
# :title => 'Sales 2002'
# )
#
# print "Content-type: image/svg+xml\r\n\r\n"
# print graph.burn
#
# = Description
#
# This object aims to allow you to easily create high quality
# SVG[http://www.w3c.org/tr/svg bar graphs. You can either use the default
# style sheet or supply your own. Either way there are many options which
# can be configured to give you control over how the graph is generated -
# with or without a key, data elements at each point, title, subtitle etc.
#
# = Notes
#
# The default stylesheet handles upto 12 data sets, if you
# use more you must create your own stylesheet and add the
# additional settings for the extra data sets. You will know
# if you go over 12 data sets as they will have no style and
# be in black.
#
# = Examples
#
# * http://germane-software.com/repositories/public/SVG/test/test.rb
#
# = See also
#
# * SVG::Graph::Graph
# * SVG::Graph::BarHorizontal
# * SVG::Graph::Line
# * SVG::Graph::Pie
# * SVG::Graph::Plot
# * SVG::Graph::TimeSeries
"""
top_align = top_font = 1
def get_x_labels(self):
return self.get_field_labels()
def get_y_labels(self):
return self.get_data_labels()
def x_label_offset(self, width):
return width / 2.0
def draw_data(self):
min_value = self.data_min()
unit_size = (float(self.graph_height) - self.font_size*2*self.top_font)
unit_size /= (max(self.get_data_values()) - min(self.get_data_values()))
bar_gap = self.get_bar_gap(self.get_field_width())
bar_width = self.get_field_width() - bar_gap
if self.stack == 'side':
bar_width /= len(self.data)
x_mod = (self.graph_width - bar_gap)/2
if self.stack == 'side':
x_mod -= bar_width/2
bottom = self.graph_height
for field_count, field in enumerate(self.fields):
for dataset_count, dataset in enumerate(self.data):
# cases (assume 0 = +ve):
# value min length
# +ve +ve value - min
# +ve -ve value - 0
# -ve -ve value.abs - 0
value = dataset['data'][field_count]
left = self.get_field_width() * field_count
length = (abs(value) - max(min_value, 0)) * unit_size
# top is 0 if value is negative
top = bottom - ((max(value,0) - min_value) * unit_size)
if self.stack == 'side':
left += bar_width * dataset_count
rect = etree.SubElement(self.graph, 'rect', {
'x': str(left),
'y': str(top),
'width': str(bar_width),
'height': str(length),
'class': 'fill%s' % (dataset_count+1),
})
self.make_datapoint_text(left + bar_width/2.0, top-6, value)
class HorizontalBar(Bar):
rotate_y_labels = True
show_x_guidelines = True
show_y_guidelines = False
right_align = right_font = True
def get_x_labels(self):
return self.get_data_labels()
def get_y_labels(self):
return self.get_field_labels()
def y_label_offset(self, height):
return height / -2.0
def draw_data(self):
min_value = self.data_min()
unit_size = float(self.graph_width)
unit_size -= self.font_size*2*self.right_font
unit_size /= max(self.get_data_values()) - min(self.get_data_values())
bar_gap = self.get_bar_gap(self.get_field_height())
bar_height = self.get_field_height() - bar_gap
if self.stack == 'side':
bar_height /= len(self.data)
y_mod = (bar_height / 2) + (self.font_size / 2)
for field_count, field in enumerate(self.fields):
for dataset_count, dataset in enumerate(self.data):
value = dataset['data'][field_count]
top = self.graph_height - (self.get_field_height() * (field_count+1))
if self.stack == 'side':
top += (bar_height * dataset_count)
# cases (assume 0 = +ve):
# value min length left
# +ve +ve value.abs - min minvalue.abs
# +ve -ve value.abs - 0 minvalue.abs
# -ve -ve value.abs - 0 minvalue.abs + value
length = (abs(value) - max(min_value, 0)) * unit_size
# left is 0 if value is negative
left = (abs(min_value) + min(value, 0)) * unit_size
rect = etree.SubElement(self.graph, 'rect', {
'x': str(left),
'y': str(top),
'width': str(length),
'height': str(bar_height),
'class': 'fill%s' % (dataset_count+1),
})
self.make_datapoint_text(left+length+5, top+y_mod, value,
"text-anchor: start; ")