import numpy as np
import matplotlib.pyplot as plt
import random

##定义数据类型
x1=np.array(range(1,4),dtype=float)
print(x1)
print(x1.dtype)

##定义数组
x2=np.array([1,2,3],dtype=int)
print(x2)
print(x2.dtype)

##调整数据类型
_x2=x2.astype(float)
print(_x2)
print(_x2.dtype)

## 生成随机小数
x3=np.array([random.random() for i in range(10)])
print(x3)
print(x3.dtype)

##保留任意位小数
_x3=np.round(x3,2)
print(_x3)
## 查看数组的形状
x4=np.array(range(10))
print(x4.shape)

## 改变数组的形状
_x4=x4.reshape(2,5)
print(_x4)

x5=np.array(range(24))
_x5=x5.reshape(2,3,4)
print("\n")
print(_x5)
## 将数组拉平
print(_x5.reshape((24,)))
print(_x5.reshape((_x5.shape[0]*_x5.shape[1]*_x5.shape[2],)))
print(_x5.flatten())      ##按行展开

## 矩阵运算
x6=np.arange(6).reshape(2,3)
x7=np.array([[4,2,3],[1,5,0]])
print(x6+x7)
print(x6-x7)
print(x6*x7)
print(x6/x7)

## 数组的轴表示，axis
## 对一位数组，只有0轴
## 对二维数组，有0轴(行的方向)和1轴(列的方向)
## 对三维数组，有0轴(表的方向)，1轴(行的方向)和2轴(列的方向)

import numpy as np
import matplotlib.pyplot as plt
import random


path="E:/Python_huatu/python_mat.numpy.pandas/siyuanshu.txt"
t=np.loadtxt(path,delimiter=",",dtype=float,unpack=False)   ##  delimiter表示分隔符，unpack=False表示不拆分

print(t)
print("#"*100)
print(t.transpose())        ##  转置
print("#"*100)
print(t.T)                  ##  转置
print("#"*100)
print(t.swapaxes(1,0))    ##  转置

################################################################################
import numpy as np
import matplotlib.pyplot as plt
import random

## 读取数据,不要使用"\",而是使用"/"
us_file_path="E:/Python_huatu/python_mat.numpy.pandas/US_video_data_numbers.csv"
uk_file_path="E:/Python_huatu/python_mat.numpy.pandas/GB_video_data_numbers.csv"

t1=np.loadtxt(us_file_path,delimiter=",",dtype=int,unpack=False)
t2=np.loadtxt(uk_file_path,delimiter=",",dtype=int,unpack=False)

print(t1)
print("~"*100)
print(t2)
## ","前是行，","后是列，":"表示所有
## 读取某一行
print("~"*100)
print(t1[2])
print(t1[2,:])

##  读取连续的多行
print("~"*100)
print(t1[2:5])
print(t1[2:5,:])

##  读取不连续的多行
print("~"*100)
print(t1[[2,8,10]])
print(t1[[2,8,10],:])

##  读取不连续的多列
print("~"*100)
print(t1[:,[0,3]])

##  读取不相邻的点
print("~"*100)
print(t1[[0,5],[2,1]])      ##  表示的是(0,2)  (5,1)