matplotlib（3.註釋、文本、多邊形、區域填充、極座標）

更新一些matplotlib繪圖周邊內容

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加箭頭註釋

import matplotlib.pyplot as plt
import numpy as np

x = np.arange(-10, 11, 1)

y = x**2

plt.plot(x, y)

# 設置顯示文本：‘this is bottom’，設置指向位置xy，設置文本位置xytext，設置箭頭參數（設置顏色：facecolor，設置箭頭的頭長：headlength，設置箭頭的頭寬：headwidth，設置箭頭的體寬：width)
plt.annotate('this is bottom', xy=(0,5), xytext=(-2,30),
             arrowprops=dict(facecolor='b', headlength=10, headwidth=30,width=10))

plt.show()

加文本Text

例1：增加文字說明

import matplotlib.pyplot as plt
import numpy as np

x = np.arange(-10, 11, 1)

y = x**2

plt.plot(x, y)

# 顯示位置x,y(2，40)，顯示內容'function:y=x*x',字體family：serif，字號size：20，顏色color:'r',樣式style:italic(斜體），字粗：black
plt.text(2, 40, 'function:y=x*x', family='serif', size=20, color='r', style='italic', weight='black')
plt.text(-7, 70, 'function:y=x*x', family='fantasy', size=30, color='g', style='oblique', weight='light', bbox=dict(facecolor='y', alpha=0.2))

plt.show()

Text屬性列表

例2：developer guide給出例子

import matplotlib.pyplot as plt
import matplotlib.patches as patches

# build a rectangle in axes coords
left, width = .25, .5
bottom, height = .25, .5
right = left + width
top = bottom + height
fig = plt.figure()
ax = fig.add_axes([0, 0, 1, 1])
# axes coordinates are 0,0 is bottom left and 1,1 is upper right
p = patches.Rectangle(
    (left, bottom), width, height,
    fill=False, transform=ax.transAxes, clip_on=False
)
ax.add_patch(p)
ax.text(left, bottom, 'left top',
        horizontalalignment='left',
        verticalalignment='top',
        transform=ax.transAxes)
ax.text(left, bottom, 'left bottom',
        horizontalalignment='left',
        verticalalignment='bottom',
        transform=ax.transAxes)
ax.text(right, top, 'right bottom',
        horizontalalignment='right',
        verticalalignment='bottom',
        transform=ax.transAxes)
ax.text(right, top, 'right top',
        horizontalalignment='right',
        verticalalignment='top',
        transform=ax.transAxes)
ax.text(right, bottom, 'center top',
        horizontalalignment='center',
        verticalalignment='top',
        transform=ax.transAxes)
ax.text(left, 0.5 * (bottom + top), 'right center', horizontalalignment='right',
        verticalalignment='center',
        rotation='vertical',
        transform=ax.transAxes)
ax.text(left, 0.5 * (bottom + top), 'left center',
        horizontalalignment='left',
        verticalalignment='center',
        rotation='vertical',
        transform=ax.transAxes)
ax.text(0.5 * (left + right), 0.5 * (bottom + top), 'middle',
        horizontalalignment='center',
        verticalalignment='center',
        fontsize=20, color='red',
        transform=ax.transAxes)
ax.text(right, 0.5 * (bottom + top), 'centered',
        horizontalalignment='center',
        verticalalignment='center',
        rotation='vertical',
        transform=ax.transAxes)
ax.text(left, top, 'rotated\nwith newlines',
        horizontalalignment='center',
        verticalalignment='center',
        rotation=45,
        transform=ax.transAxes)
ax.set_axis_off()
plt.show()

LaTeX公式

Writing mathematical expressions

和CSDN博客支持的LaTeX數學公式相同，這是一種單獨的公式表示方式，可以自行搜索其語法。

例1：簡單寫四個公式demo

import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()

ax = fig.add_subplot(111)

ax.set_xlim([1, 7])

ax.set_ylim([1, 5])

ax.text(2, 4, r"$ \alpha_i \beta_j \pi \lambda \omega $",size=20)

ax.text(4,4, r"$ \sin(0)=\cos(\frac{\pi}{2}) $",size=25)

ax.text(2,2,r"$ \lim_{x \rightarrow y}\frac{1}{x^3}  $",size=25,color='b')

ax.text(4,2,r"$ \sqrt[4]{x}=\sqrt{y} $",size=25)
plt.show()

區域填充

fill, fill_between

例1：fill函數方式

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0,5*np.pi,1000)

y1 = np.sin(x)

y2 = np.sin(2*x)

plt.plot(x,y1)

plt.plot(x,y2)

plt.fill(x,y1,'b',alpha=0.3)

plt.fill(x,y2,'r',alpha=0.3)

plt.show()

可以看到：fill填充了函數與X軸之間的區域

例2：fill_between

x = np.linspace(0,5*np.pi,1000)

y1 = np.sin(x)

y2 = np.sin(2*x)

fig = plt.figure()

ax = fig.gca()

ax.plot(x,y1,x,y2,color='black')

# 填充y1,y2之間，當y1>y2時，填充黃色，離散區域自動填充interpolate=True
ax.fill_between(x,y1,y2,where=y1>y2,facecolor='y',interpolate=True)

# 填充y1,y2之間，當y1<y2時，填充綠色，離散區域自動填充interpolate=True
ax.fill_between(x,y1,y2,where=y1<y2,facecolor='g',interpolate=True)
plt.show()

繪製多邊圖形

例1：繪製圓形，橢圓形，長方形，多邊形

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.patches as mpatches

fig, ax = plt.subplots()

# 指定圖形位置
xy1 = np.array([0.2, 0.2])

# 圓半徑0.05
circle = mpatches.Circle(xy1, 0.05)

ax.add_patch(circle)

# rectangle左下角位置
xy2 = np.array([0.2, 0.8])
# 長方形長0.2，寬0.1
rect = mpatches.Rectangle(xy2, 0.2, 0.1, color='r')
ax.add_patch(rect)

xy3 = np.array([0.8, 0.2])
# 多邊形：5條邊，圖形中心到邊的距離爲0.1
polygon=mpatches.RegularPolygon(xy3,5,0.1,color='g')
ax.add_patch(polygon)

xy4=np.array([0.8,0.8])
# 橢圓長短直徑0.4\0.2
ellipse=mpatches.Ellipse(xy4,0.4,0.2,color='y')
ax.add_patch(ellipse)

plt.axis('equal')
plt.grid()

plt.show()

極座標

確定角度和距離即可作圖

例1：繪製距離1-5，角度0-2pi的圖

r = np.arange(1, 6, 1)

theta = [0, np.pi / 2, np.pi, np.pi * 3 / 2, 2 * np.pi]

# 投影成極座標=》projection='polar'
ax = plt.subplot(111, projection='polar')

ax.plot(theta, r, color='r', linewidth=3)

ax.grid(True)

plt.show()

後面開始更新實戰例子