plt.text()函数解析（最清晰的解释）

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plt.text()函数用于设置文字说明。

plt.text(x,
	y,
	string,
	fontsize=15,
	verticalalignment="top",
	horizontalalignment="right"
)

参数：

• x,y:表示坐标值上的值

• string:表示说明文字

• fontsize:表示字体大小

• verticalalignment：垂直对齐方式 ，参数：[ ‘center’ | ‘top’ | ‘bottom’ | ‘baseline’ ]

• horizontalalignment：水平对齐方式 ，参数：[ ‘center’ | ‘right’ | ‘left’ ]

• xycoords选择指定的坐标轴系统:

  • figure points：图左下角的点
  • figure pixels：图左下角的像素
  • figure fraction：图的左下部分
  • axes points：坐标轴左下角的点
  • axes pixels：坐标轴左下角的像素
  • axes fraction：左下轴的分数
  • data：使用被注释对象的坐标系统(默认)
  • polar(theta,r)：if not native ‘data’ coordinates t

• arrowprops #箭头参数,参数类型为字典dict

  • width：箭头的宽度(以点为单位)
  • headwidth：箭头底部以点为单位的宽度
  • headlength：箭头的长度(以点为单位)
  • shrink：总长度的一部分，从两端“收缩”
  • facecolor：箭头颜色

• bbox给标题增加外框 ，常用参数如下：

  • boxstyle：方框外形
  • facecolor：(简写fc)背景颜色
  • edgecolor：(简写ec)边框线条颜色
  • edgewidth：边框线条大小

例子1：

import matplotlib.pyplot as plt

fig = plt.figure()
plt.axis([0, 10, 0, 10])
t = "This is a really long string that I'd rather have wrapped so that it"
    " doesn't go outside of the figure, but if it's long enough it will go"
    " off the top or bottom!"
plt.text(4, 1, t, ha='left', rotation=15, wrap=True)
plt.text(6, 5, t, ha='left', rotation=15, wrap=True)
plt.text(6, 5, t, ha='left', rotation=15, wrap=False)
plt.show()

（x，y）参数是句子头的坐标。

例子2：

import matplotlib.pyplot as plt

fig = plt.figure()
plt.axis([0, 10, 0, 10])
t = "This is a really long string that I'd rather have wrapped so that it"
    " doesn't go outside of the figure, but if it's long enough it will go"
    " off the top or bottom!"
plt.text(6, 5, t, ha='left', rotation=15, wrap=True)
plt.text(6, 5, t, ha='left', rotation=-15, wrap=True)
plt.text(6, 5, t, ha='left', rotation=-50, wrap=True)
plt.show()

1. ha为’left’参数, rotation>0的时候，句子头这一侧更低。
2. ha为’left’参数, rotation<0的时候，做上面的1的关于水平坐标轴的镜像。
3. rotation参数是和水平坐标轴的夹角。

例子3：

import matplotlib.pyplot as plt

fig = plt.figure()
plt.axis([0, 10, 0, 10])
t = "This is a really long string that I'd rather have wrapped so that it"
    " doesn't go outside of the figure, but if it's long enough it will go"
    " off the top or bottom!"
plt.text(6, 5, t, ha='left', rotation=15, wrap=True)
plt.text(5, 10, t, fontsize=18, style='oblique', ha='center',va='top',wrap=True)
plt.show()

fontsize，style，ha，va参数分别是字号，字体，垂直对齐方式，水平对齐方式。

例子4：

import matplotlib.pyplot as plt

fig = plt.figure()
plt.axis([0, 10, 0, 10])
t = "This is a really long string that I'd rather have wrapped so that it"
    " doesn't go outside of the figure, but if it's long enough it will go"
    " off the top or bottom!"
plt.text(6, 5, t, ha='left', rotation=15, wrap=True)
plt.text(4, 4, t, family='serif', style='italic', ha='right', wrap=True)
plt.text(4, 6, t, style='italic', ha='right', wrap=True)
plt.show()

family参数应该是一个字体参数。

例子4：

import matplotlib.pyplot as plt

fig = plt.figure()
plt.axis([0, 10, 0, 10])
t = "This is a really long string that I'd rather have wrapped so that it"
    " doesn't go outside of the figure, but if it's long enough it will go"
    " off the top or bottom!"
plt.text(6, 5, t, ha='left', rotation=15, wrap=True)
plt.text(2, 5, t, ha='left', rotation=15, wrap=True,  bbox=dict(boxstyle='round,pad=0.5', fc='yellow', ec='k',lw=1 ,alpha=0.5))
plt.show()

这个参数和plt.annotate()一样。

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