day 18 numpy模块/matplotlib模块/pandas模块

目录

• numpy模块
  • numpy数组
  • 通过函数创建numpy数组
  • numpy数组的运算
  • numpy.random
• matplotlib模块
  • 条形图

numpy模块

numpy模块:用来做数据分析

numpy数组

import numpy as np

arr1 = np.array([1, 2, 3])
arr2 = np.array([4, 5, 6])
print(arr1 * arr2)

[ 4 10 18]

# 一位数组
arr = np.array([1, 2, 4])
print(type(arr), arr)

<class 'numpy.ndarray'> [1 2 4]

# 二维数组
arr = np.array([
	[1, 2, 3],
    [4, 5, 6]
])
print(arr)

[[1 2 3]
 [4 5 6]]

# 三维数组(不在讨论范围内)
arr3 = np.array([
    [[1, 2, 3],
     [4, 5, 6]],
    [[1, 2, 3],
     [4, 5, 6]],
])

arr = np.array([
	[1, 2, 3],
    [4, 5, 6]
])

# T 数组的转置 --> 行列互换
print(arr, '
', arr.T)

# dtype 数组元素的数据类型.numpy数组是属于python解释器的;int32,float64是属于numpy的
print(arr.dtype)

[[1 2 3]
 [4 5 6]] 
 [[1 4]
 [2 5]
 [3 6]]
int32

arr = np.array([
	[1, 2, 3],
    [4, 5, 6]
])

# size 数组元素的个数
print(arr.size)
# ndim 数组的维数
print(arr.ndim)
# shape 数组的维度大小(以元组形式)
print(arr.shape)
# astype 转换数据类型
arr = arr.astype(np.float64)
print(arr)

6
2
(2, 3)
[[1. 2. 3.]
 [4. 5. 6.]]

arr = np.array([
	[1, 2, 3],
    [4, 5, 6]
])

# 切片
print(arr[:, :])  # 行,列
print(arr[0, 0])
print(arr[0, :])
print(arr[:2, -2:])
print(arr[arr > 4])  # 逻辑取值

[[1 2 3]
 [4 5 6]]
1
[1 2 3]
[[2 3]
 [5 6]]
[5 6]

arr = np.array([
	[1, 2, 3],
    [4, 5, 6]
])

# 赋值
arr[0, 0] = 0
print(arr)
arr[0, :] = 0
print(arr)
arr[:, :] = 0
print(arr)

[[0 2 3]
 [4 5 6]]
[[0 0 0]
 [4 5 6]]
[[0 0 0]
 [0 0 0]]

# 数组的合并
arr1 = np.array([
    [1, 2, 3],
    [4, 5, 6]
])

arr2 = np.array([
    [7, 8, 9],
    ['a', 'b', 'c']
])

# 行合并
print(np.hstack((arr1, arr2)))  # 只能放元组
# 列合并
print(np.vstack((arr1, arr2)))
# 默认以列合并 0表示列, 1表示行
print(np.concatenate((arr1, arr2), axis=1))

[['1' '2' '3' '7' '8' '9']
 ['4' '5' '6' 'a' 'b' 'c']]
[['1' '2' '3']
 ['4' '5' '6']
 ['7' '8' '9']
 ['a' 'b' 'c']]
[['1' '2' '3' '7' '8' '9']
 ['4' '5' '6' 'a' 'b' 'c']]

通过函数创建numpy数组

# 通过函数创建numpy数组
print(np.ones((2, 3)))

print(np.zeros((3, 3)))

print(np.eye(3, 3))

print(np.linspace(1, 100, 10))

print(np.arange(2, 10))

arr1 = np.zeros((3, 3))
print(arr1.reshape((1, 9)))  # 重构数组形状

[[1. 1. 1.]
 [1. 1. 1.]]
[[0. 0. 0.]
 [0. 0. 0.]
 [0. 0. 0.]]
[[1. 0. 0.]
 [0. 1. 0.]
 [0. 0. 1.]]
[  1.  12.  23.  34.  45.  56.  67.  78.  89. 100.]
[2 3 4 5 6 7 8 9]
[[0. 0. 0. 0. 0. 0. 0. 0. 0.]]

numpy数组的运算

# 数组的运算(+-*)
arr1 = np.ones((3, 4)) * 4
print(arr1)

# 数组的运算函数
arr1 = np.sin(arr1)
print(arr1)

# 矩阵运算--点乘
arr1 = np.array([
    [1, 2, 3],
    [4, 5, 6]
])

arr2 = np.array([
    [1, 2],
    [4, 5],
    [6, 7]
])

print(np.dot(arr1, arr2))

# 求逆
arr = np.array([[1, 2, 3], [4, 5, 6], [9, 8, 9]])
print(np.linalg.inv(arr))

# numpy数组和统计方法
print(np.sum(arr[0,:]))

[[4. 4. 4. 4.]
 [4. 4. 4. 4.]
 [4. 4. 4. 4.]]
[[-0.7568025 -0.7568025 -0.7568025 -0.7568025]
 [-0.7568025 -0.7568025 -0.7568025 -0.7568025]
 [-0.7568025 -0.7568025 -0.7568025 -0.7568025]]
[[27 33]
 [60 75]]
[[ 0.5        -1.          0.5       ]
 [-3.          3.         -1.        ]
 [ 2.16666667 -1.66666667  0.5       ]]
6

numpy.random

# numpy.random生成随机数
print(np.random.rand(3, 4))

print(np.random.random((3, 4)))

np.random.seed(1)
print(np.random.random((3, 4)))

# s = np.random.RandomState(1)  # 效果和seed相同
# print(s.random((3, 4)))

arr = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
np.random.shuffle(arr)
print(arr)

# 针对一维
print(np.random.choice([1, 2, 3], 1))

# 针对某一个范围
print(np.random.randint(1, 100, (3, 4)))

[[0.53896726 0.71229709 0.92507313 0.31876484]
 [0.83072795 0.63231691 0.15914402 0.63281235]
 [0.75497099 0.00880939 0.2655119  0.34494942]]
[[0.734392   0.93710219 0.70851098 0.03865121]
 [0.4247206  0.64120213 0.47434356 0.32331907]
 [0.23769872 0.96864964 0.60257089 0.01608933]]
[[4.17022005e-01 7.20324493e-01 1.14374817e-04 3.02332573e-01]
 [1.46755891e-01 9.23385948e-02 1.86260211e-01 3.45560727e-01]
 [3.96767474e-01 5.38816734e-01 4.19194514e-01 6.85219500e-01]]
[[7 8 9]
 [1 2 3]
 [4 5 6]]
[1]
[[95 23 67 66]
 [93 13 43 81]
 [50 72 46 84]]

matplotlib模块

matplotlib模块：画图

条形图

from matplotlib import pylot as pit
from matplotlib.font_manager import FontProperties  # 修改字体

font = FontProperties(fname='C:WindowsFontssimsun.ttc')