PyChartDirector中文教程[7]：饼图的标签

May 13	PyChartDirector中文教程[7]：饼图的标签
	Categories: Python \| Tags: ChartDirector, Python \| Views: 2,438

下面我们看看如何用不同的方式来显示饼图的标签

1. 侧边标签层

先看看效果图:

标签的效果: 金属背景颜色, 圆角, 玻璃阴影效果

侧边标签层的标签将放置在图表的左侧和右侧

侧边标签层有一个好处, 那就是标签会自动上下排列, 防止交叠.

金色的背景由 pychartdir.goldColor产生

粉色金属背景由pychartdir.metalColor产生, 用Box.setBackground来设置标题TextBox的背景颜色

侧边标签层由PieChart.setLabelLayout来指定

玻璃效果由pychartdir.glassEffect来增加, 用Box.setBackground来分别指定

圆角标签用Box.setRoundedCorners来设置

如果数据中有些排序好的小值, 这个小值代表的块将会被放在一起, 这样标签就不需要太多的移动, 这个小值块更多的是在左边或者右边,而不是上边或者下边.

如果数据是降序排列的, 那么图的初始角度是顺时针135度,来保证那些小值块在45-135之间(在图的右边), 如果是升序, 则初始角度是45度.

代码:

#!/usr/bin/python
from pychartdir import *
 
# The data for the pie chart
data = [35, 30, 25, 7, 6, 5, 4, 3, 2, 1]
 
# The labels for the pie chart
labels = ["Labor", "Production", "Facilities", "Taxes", "Misc", "Legal", "Insurance",
    "Licenses", "Transport", "Interest"]
 
# Create a PieChart object of size 560 x 270 pixels, with a golden background and a 1
# pixel 3D border
c = PieChart(560, 270, goldColor(), -1, 1)
 
# Add a title box using 15 pts Times Bold Italic font and metallic pink background
# color
c.addTitle("Project Cost Breakdown", "timesbi.ttf", 15).setBackground(metalColor(
    0xff9999))
 
# Set the center of the pie at (280, 135) and the radius to 110 pixels
c.setPieSize(280, 135, 110)
 
# Draw the pie in 3D with 20 pixels 3D depth
c.set3D(20)
 
# Use the side label layout method
c.setLabelLayout(SideLayout)
 
# Set the label box background color the same as the sector color, with glass effect,
# and with 5 pixels rounded corners
t = c.setLabelStyle()
t.setBackground(SameAsMainColor, Transparent, glassEffect())
t.setRoundedCorners(5)
 
# Set the border color of the sector the same color as the fill color. Set the line
# color of the join line to black (0x0)
c.setLineColor(SameAsMainColor, 0x000000)
 
# Set the start angle to 135 degrees may improve layout when there are many small
# sectors at the end of the data array (that is, data sorted in descending order). It
# is because this makes the small sectors position near the horizontal axis, where
# the text label has the least tendency to overlap. For data sorted in ascending
# order, a start angle of 45 degrees can be used instead.
c.setStartAngle(135)
 
# Set the pie data and the pie labels
c.setData(data, labels)
 
# Output the chart
c.makeChart("sidelabelpie.png")

2. 环形标签层

看效果图:

这种环形标签有几种效果, 默认地是像最开始的例子那样,在图表的外面,紧挨着图.

Pie.setLabelPos可以用来控制标签与圆周之间的距离. 并可以在圆周和标签之间添加连接线, 当标签比较远的时候连接线是很有用的.

如果标签与圆周之间的距离是负值, 那么标签将会显示在圆周之内.

代码:

#!/usr/bin/python
from pychartdir import *
 
def createChart(img) :
 
    # The data for the pie chart
    data = [42, 18, 8]
 
    # The labels for the pie chart
    labels = ["Agree", "Disagree", "Not Sure"]
 
    # The colors to use for the sectors
    colors = [0x66ff66, 0xff6666, 0xffff00]
 
    # Create a PieChart object of size 300 x 300 pixels. Set the background to a
    # gradient color from blue (aaccff) to sky blue (ffffff), with a grey (888888)
    # border. Use rounded corners and soft drop shadow.
    c = PieChart(300, 300)
    c.setBackground(c.linearGradientColor(0, 0, 0, c.getHeight() / 2, 0xaaccff,
        0xffffff), 0x888888)
    c.setRoundedFrame()
    c.setDropShadow()
 
    if img == "0" :
    #============================================================
    #    Draw a pie chart where the label is on top of the pie
    #============================================================
 
        # Set the center of the pie at (150, 150) and the radius to 120 pixels
        c.setPieSize(150, 150, 120)
 
        # Set the label position to -40 pixels from the perimeter of the pie (-ve
        # means label is inside the pie)
        c.setLabelPos(-40)
 
    else :
    #============================================================
    #    Draw a pie chart where the label is outside the pie
    #============================================================
 
        # Set the center of the pie at (150, 150) and the radius to 80 pixels
        c.setPieSize(150, 150, 80)
 
        # Set the sector label position to be 20 pixels from the pie. Use a join line
        # to connect the labels to the sectors.
        c.setLabelPos(20, LineColor)
 
 
    # Set the pie data and the pie labels
    c.setData(data, labels)
 
    # Set the sector colors
    c.setColors2(DataColor, colors)
 
    # Use local gradient shading, with a 1 pixel semi-transparent black (bb000000)
    # border
    c.setSectorStyle(LocalGradientShading, 0xbb000000L, 1)
 
    # Output the chart
    c.makeChart("circlelabelpie%s.png" % img)
 
 
createChart("0")
createChart("1")