python3_matplotlib_figure()函数解析

1.绘图库导入

import numpy as np
import matplotlib.pyplot as plt

2.创建一个图形实例

plt.figure(figsize=(15,5))

figure说明：The Figure instance returned will also be passed to new_figure_manager in the backends, which allows to hook custom Figure classes into the pylab interface. Additional kwargs will be passed to the figure init function。

含义猜测：通过new_figure_manager（新图形管理器）返回一个figure图形实例。定制的figure类将与pylab接口进行关联，同时将相关参数传递给figure的初始化函数。    

note:If you are creating many figures, make sure you explicitly call "close" on the figures you are not using, because this will enable pylab to properly clean up the memory.

注意：如果你创建了多个figure实例，必须确保你显式的调用“close”来释放你已经不再使用的figure实例。因为只有这样pylab才能正确的释放内存。

3.函数头：

def figure(num=None, figsize=None, dpi=None, facecolor=None, edgecolor=None, frameon=True, FigureClass=Figure, clear=False, **kwargs)

4.参数说明:

num : integer or string, optional, default: none
If not provided, a new figure will be created, and the figure number will be incremented. The figure objects holds this number in a number attribute. If num is provided, and a figure with this id already exists, make it active, and returns a reference to it. If this figure does not exists, create it and returns it. If num is a string, the window title will be set to this figure's num.

num:如果此参数没有提供，则一个新的figure对象将被创建，同时增加figure的计数数值，此数值被保存在figure对象的一个数字属性当中。如果有此参数，且存在对应id的figure对象，则激活对于id的figure对象。如果对应id的figur对象不存在，则创建它并返回它。如果num的值是字符串，则将窗口标题设置为此字符串。

figsize : tuple of integers, optional, default: None

width, height in inches. If not provided, defaults to rc figure.figsize

figsize:以英寸为单位的宽高，缺省值为 rc figure.figsize (1英寸等于2.54厘米)

实验：

import numpy as np
import matplotlib.pyplot as plt

fig1 = plt.figure(num="3*1 inches",figsize=(3,1))
fig2 = plt.figure(num="6*2 inches",figsize=(6,2))

plt.show()
plt.close

运行结果如下：

num深入实验

import numpy as np
import matplotlib.pyplot as plt

fig1 = plt.figure(num='fig1',figsize=(6,3),dpi=75,facecolor='#666666',edgecolor='#0000FF')
fig2 = plt.figure(num='fig2',figsize=(6,3),dpi=75,facecolor='#FFFFFF',edgecolor='#FF0000')
plt.xlim(0,20)
plt.ylim(0,10)

plt.show()
plt.close()

运行结果：

我建立了两个figure图，plt.xlim，plt.ylim只给最后创建的figure（fig2）配置，如果我想给第一个figure配置xlim与lim该怎么做？这个时候就可以用num参数了 。

import numpy as np
import matplotlib.pyplot as plt

fig1 = plt.figure(num='fig1',figsize=(6,3),dpi=75,facecolor='#666666',edgecolor='#0000FF')
fig2 = plt.figure(num='fig2',figsize=(6,3),dpi=75,facecolor='#FFFFFF',edgecolor='#FF0000')
plt.xlim(0,20)
plt.ylim(0,10)

plt.figure(num='fig1')
plt.xlim(0,20)
plt.ylim(0,10)

plt.show()
plt.close()

实验结果：

dpi : integer, optional, default: None

resolution of the figure. If not provided, defaults to rc figure.dpi.

dpi:图形分辨率，缺省值为rc figure.dpi

实验：

import numpy as np
import matplotlib.pyplot as plt

fig1 = plt.figure(num="dpi=72",figsize=(6,2),dpi=72)
fig2 = plt.figure(num="dpi=100",figsize=(6,2),dpi=100)

plt.show()
plt.close

相同的figsize，不同的dpi，可见dpi越大则图形越大

facecolor :

the background color. If not provided, defaults to rc figure.facecolo

facecolor：背景色

edgecolor :

the border color. If not provided, defaults to rc figure.edgecolor

edgecolor:边框颜色

frameon : bool, optional, default: True

If False, suppress drawing the figure frame.

frameon：默认值True为绘制边框，如果为False则不绘制边框

FigureClass : class derived from matplotlib.figure.Figure

Optionally use a custom Figure instance.

FigureClass:matplotlib.figure.Figure派生类，从派生类创建figure实例

clear : bool, optional, default: False

If True and the figure already exists, then it is cleared

clear：重建figure实例