python 畫餅圖

畫餅圖用到的方法為：

matplotlib.pyplot.pie()

參數為：

[python] view plain copy

1. pie(x, explode=None, labels=None,
2. colors=("b", "g", "r", "c", "m", "y", "k", "w"),
3. autopct=None, pctdistance=0.6, shadow=False,
4. labeldistance=1.1, startangle=None, radius=None,
5. counterclock=True, wedgeprops=None, textprops=None,
6. center = (0, 0), frame = False )

參數說明：

x (每一塊)的比例，如果sum(x) > 1會使用sum(x)歸一化

labels (每一塊)餅圖外側顯示的說明文字

explode (每一塊)離開中心距離

startangle 起始繪製角度,默認圖是從x軸正方向逆時針畫起,如設定=90則從y軸正方向畫起

shadow 是否陰影

labeldistance label繪製位置,相對於半徑的比例, 如<1則繪製在餅圖內側

autopct 控制餅圖內百分比設置,可以使用format字元串或者format function

"%1.1f"指小數點前後位數(沒有用空格補齊)

pctdistance 類似於labeldistance,指定autopct的位置刻度

radius 控制餅圖半徑

返回值:

如果沒有設置autopct,返回(patches, texts)

如果設置autopct,返回(patches, texts, autotexts)

patches -- list --matplotlib.patches.Wedge對象

texts autotexts -- matplotlib.text.Text對象

下面是一個簡單的示例：

[python] view plain copy

1. # -*- coding: utf-8 -*-

2. import

   numpy as np

3. import

   matplotlib.mlab as mlab

4. import

   matplotlib.pyplot as plt

5. labels=["China","Swiss","USA","UK","Laos","Spain"]
6. X=[222,42,455,664,454,334]
8. fig = plt.figure()
9. plt.pie(X,labels=labels,autopct="%1.2f%%") #畫餅圖（數據，數據對應的標籤，百分數保留兩位小數點）
10. plt.title("Pie chart")
13. plt.show()
14. plt.savefig("PieChart.jpg")

下面是結果：

下面是另一個示例：

[python] view plain copy

1. # -*- coding: utf-8 -*-

2. import

   numpy as np

3. import

   matplotlib.pyplot as plt

4. import

   matplotlib as mpl

6. def

   draw_pie(labels,quants):
7. # make a square figure
8. plt.figure(1, figsize=(6,6))
9. # For China, make the piece explode a bit
10. expl = [0,0.1,0,0,0,0,0,0,0,0] #第二塊即China離開圓心0.1
11. # Colors used. Recycle if not enough.
12. colors = ["blue","red","coral","green","yellow","orange"] #設置顏色（循環顯示）
13. # Pie Plot
14. # autopct: format of "percent" string;百分數格式
15. plt.pie(quants, explode=expl, colors=colors, labels=labels, autopct="%1.1f%%",pctdistance=0.8, shadow=True)
16. plt.title("Top 10 GDP Countries", bbox={"facecolor":"0.8", "pad":5})
17. plt.show()
18. plt.savefig("pie.jpg")
19. plt.close()
21. # quants: GDP
23. # labels: country name
25. labels = ["USA", "China", "India", "Japan", "Germany", "Russia", "Brazil", "UK", "France", "Italy"]
27. quants = [15094025.0, 11299967.0, 4457784.0, 4440376.0, 3099080.0, 2383402.0, 2293954.0, 2260803.0, 2217900.0, 1846950.0]
29. draw_pie(labels,quants)

官方文檔：

鏈接：http://matplotlib.org/api/pyplot_api.html

matplotlib.pyplot.pie(x, explode=None, labels=None, colors=None, autopct=None, pctdistance=0.6, shadow=False, labeldistance=1.1, startangle=None,radius=None, counterclock=True, wedgeprops=None, textprops=None, center=(0, 0), frame=False, hold=None, data=None)Plot a pie chart.

Call signature:

pie(x, explode=None, labels=None,
colors=("b", "g", "r", "c", "m", "y", "k", "w"),
autopct=None, pctdistance=0.6, shadow=False,
labeldistance=1.1, startangle=None, radius=None,
counterclock=True, wedgeprops=None, textprops=None,
center = (0, 0), frame = False )

Make a pie chart of array x. The fractional area of each wedge is given by x/sum(x). If sum(x) <= 1, then the values of x give the fractional area directly and the array will not be normalized. The wedges are plotted counterclockwise, by default starting from the x-axis.

Keyword arguments:

explode: [ None | len(x) sequence ]

If not None, is a len(x) array which specifies the fraction of the radius with which to offset each wedge.

colors: [ None | color sequence ]

A sequence of matplotlib color args through which the pie chart will cycle.

labels: [ None | len(x) sequence of strings ]

A sequence of strings providing the labels for each wedge

autopct: [ None | format string | format function ]

If not None, is a string or function used to label the wedges with their numeric value. The label will be placed inside the wedge. If it is a format string, the label will be fmt%pct. If it is a function, it will be called.

pctdistance: scalar

The ratio between the center of each pie slice and the start of the text generated by autopct. Ignored if autopct is None; default is 0.6.

labeldistance: scalar

The radial distance at which the pie labels are drawn

shadow: [ False | True ]

Draw a shadow beneath the pie.

startangle: [ None | Offset angle ]

If not None, rotates the start of the pie chart by angle degrees counterclockwise from the x-axis.

radius: [ None | scalar ] The radius of the pie, if radius is None it will be set to 1.

counterclock: [ False | True ]

Specify fractions direction, clockwise or counterclockwise.

wedgeprops: [ None | dict of key value pairs ]

Dict of arguments passed to the wedge objects making the pie. For example, you can pass in wedgeprops = { 『linewidth』 : 3 } to set the width of the wedge border lines equal to 3. For more details, look at the doc/arguments of the wedge object. By default clip_on=False.

textprops: [ None | dict of key value pairs ]

Dict of arguments to pass to the text objects.

center: [ (0,0) | sequence of 2 scalars ] Center position of the chart.

frame: [ False | True ]

Plot axes frame with the chart.

The pie chart will probably look best if the figure and axes are square, or the Axes aspect is equal. e.g.:

figure(figsize=(8,8))
ax = axes([0.1, 0.1, 0.8, 0.8])

or:

axes(aspect=1)

Return value:

If autopct is None, return the tuple (patches, texts):

• patches is a sequence of matplotlib.patches.Wedge instances
• texts is a list of the label matplotlib.text.Text instances.

If autopct is not None, return the tuple (patches, texts, autotexts), where patches and texts are as above, and autotexts is a list of Textinstances for the numeric labels.

Notes

In addition to the above described arguments, this function can take a data keyword argument. If such a data argument is given, the following arguments are replaced by data[<arg>]:

• All arguments with the following names: 『colors』, 『x』, 『explode』, 『labels』.

Additional kwargs: hold = [True|False] overrides default hold state

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