小试牛刀Matplotlib

1、plt.subplot()

import matplotlib.pyplot as plt

# Integer subplot specification must be a three digit number
# 前两位代表横竖长度比
# 左边的代表横，中间的代标纵坐标，右边的则表示绘图位置（当横纵比不是1：1时）
ax1, ax2, ax3 = plt.subplot(231), plt.subplot(232), plt.subplot(233)
ax4, ax5, ax6 = plt.subplot(234), plt.subplot(235), plt.subplot(236)
# 被注释的地方xy(x, y)和插入文本的地方xytext(x, y)
ax2.annotate("Test", xy=(0.5, 0.5), xycoords=ax1.transData,
             xytext=(0.5, 0.5), textcoords=ax2.transData,
             arrowprops=dict(arrowstyle="<-"))
ax3.annotate("ax3", xy=(0.5, 0.5), xytext=(0.5, 0.5))
ax4.annotate("ax4", xy=(0.5, 0.5), xytext=(0.5, 0.5))
ax5.annotate("ax5", xy=(0.5, 0.5), xytext=(0.5, 0.5))
ax6.annotate("ax6", xy=(0.5, 0.5), xytext=(0.5, 0.5))
plt.show()

2、annotate

被注释的地方xy(x, y)和插入文本的地方xytext(x, y)
xycoords和textcoords指定xy和xytext的坐标系。默认为data（使用轴域数据坐标系）

| 参数 | 坐标系 |

| 'data' | 使用轴域数据坐标系 |

import matplotlib.pyplot as plt
from numpy import *


ax1 = plt.subplot(111)

t = arange(0.0, 5.0, 0.01)
s = cos(2*pi*t)
line = plt.plot(t, s, lw=2)
# 被注释的地方xy(x, y)和插入文本的地方xytext(x, y)
# xycoords和textcoords指定xy和xytext的坐标系。默认为data（使用轴域数据坐标系）

ax1.annotate('local max', xy=(2, 1), xytext=(3, 1.5),
            arrowprops=dict(facecolor='black'))

plt.ylim(-2, 2)
plt.show()

3、在机器学习实战的第三章，我们还用到了箭头(arrow)和文本框(box)

import matplotlib.pyplot as plt

# boxstyle文本框样式， fc(face color)背景透明度
decisionNode = dict(boxstyle="round4, pad=0.5", fc="0.8")
leafNode = dict(boxstyle="circle", fc="0.8")
# 箭头样式
arrow_args = dict(arrowstyle="<-")


def plotNode(nodeTxt, centerPt, parentPt, nodeType):
    createPlot.ax1.annotate(nodeTxt, xy=parentPt, xycoords="axes fraction",
                            xytext=centerPt, textcoords="axes fraction", va="center",
                            ha="center", bbox=nodeType, arrowprops=arrow_args)


def createPlot():
    fig = plt.figure(1, facecolor="white")
    fig.clf()
    createPlot.ax1 = plt.subplot(111, frameon=False)
    plotNode('决策点', (0.5, 0.1), (0.1, 0.5), decisionNode)
    plotNode('叶节点', (0.8, 0.1), (0.3, 0.8), leafNode)
    # plt.rcParams['font.sans-serif'] = ['SimHei']
    plt.show()


createPlot()

Annotating with Text with Box：boxstyle

Class	Name	Attrs
Circle	circle	pad=0.3
DArrow	darrow	pad=0.3
LArrow	larrow	pad=0.3
RArrow	rarrow	pad=0.3
Round	round	pad=0.3,rounding_size=None
Round4	round4	pad=0.3,rounding_size=None
Roundtooth	roundtooth	pad=0.3,tooth_size=None
Sawtooth	sawtooth	pad=0.3,tooth_size=None
Square	square	pad=0.3

Annotating with Arrow：arrowstyle

Name	Attrs
-	None
->	head_length=0.4,head_width=0.2
-[	widthB=1.0,lengthB=0.2,angleB=None
\|-\|	widthA=1.0,widthB=1.0
-\|>	head_length=0.4,head_width=0.2
<-	head_length=0.4,head_width=0.2
<->	head_length=0.4,head_width=0.2
<\|-	head_length=0.4,head_width=0.2
<\|-\|>	head_length=0.4,head_width=0.2
fancy	head_length=0.4,head_width=0.4,tail_width=0.4
simple	head_length=0.5,head_width=0.5,tail_width=0.2
wedge	tail_width=0.3,shrink_factor=0.5

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