Matplotlib 基礎知識

1.繪製正弦

from matplotlib.pyplot import plot, show
import math

T = range(100)  # 0~99

# X周的範圍2pi，分紅100份
X = [(2 * math.pi) * t / len(T) for t in T]
# sin和cos
Y = [math.sin(value) for value in X]
print(X)

plot(X, Y)
# 繪製
show()

2.在同一個二維座標系繪製出一元二次曲線和正弦、餘弦曲線

import numpy
from matplotlib.pyplot import plot, show

# 在同一個二維座標系繪製出一元二次曲線和正弦、餘弦曲線


# 一元二次方程
X = numpy.linspace(-3, 3, 200)
Y = X ** 2 - 2 * X + 1
plot(X, Y)

# sin
X = numpy.linspace(0, 2 * numpy.pi, 100)
Y = numpy.sin(X)

plot(X, Y)

# cos
X = numpy.linspace(0, 2 * numpy.pi, 100)
Y = numpy.cos(X)

plot(X, Y)

show()

3.繪製隨機點

import random
import matplotlib.pyplot as plt

# 繪製隨機點

count = 1024

X = [random.random() for i in range(count)]

Y = [random.random() for i in range(count)]

# 繪製連續的
# plt.plot(X, Y)
# 繪製隨機的
plt.scatter(X, Y)
plt.show()

4.繪製垂直柱狀圖

from matplotlib.pyplot import plot, show, bar, barh

# 繪製垂直柱狀圖
# x座標
X = [0, 1, 2, 3]
# y軸座標
Y = [22, 11, 44, 15]

bar(X, Y)

show()

5.繪製多組垂直柱狀圖

import matplotlib.pyplot as plt

# 繪製多組垂直柱狀圖
Y = [
    [11, 22, 44, 66],
    [55, 66, 77, 22],
    [44, 55, 66, 77]
]

plt.bar(range(4), Y[0], width=0.25)
plt.bar([x + 0.25 for x in range(4)], Y[1], width=0.25)
plt.bar([x + 0.5 for x in range(4)], Y[2], width=0.25)

plt.show()

6.在同一個窗口繪製直方圖和盒狀圖

import numpy

import matplotlib.pyplot as plot

# hist:直方圖
# boxplot:盒狀圖

# randn函數返回一個或一組樣本，具備標準正態分佈
data = numpy.random.randn(100)
# print(data)
print("平均值==", numpy.average(data))

# 把顯示分爲兩個區域
fig, (ax1, ax2) = plot.subplots(1, 2, figsize=(8, 4))
print(fig)  # Figure(800x400)

# 直方圖，分爲100份
ax1.hist(data, 100)
# 盒狀圖
ax2.boxplot(data)

# 顯示
plot.show()

7.繪製有百分比和標籤的餅狀圖

import matplotlib.pyplot as plt

X = [22, 33, 11, 66]
labels = ["張三", "李四", "王二", "麻子"]

plt.pie(X, autopct="%.2f%%", labels=labels)

plt.legend(labels)

plt.axis("equal")

plt.show()