pygal/svg/charts/bar.py

#!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

	css_file = '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; ")