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四、文件的读写

# 四、文件的读写

# 4.1 python 内置方法

# 4.1.1 读

步骤：

  1. open
  2. read、readline、readlines
  3. close
try:
    file = open('./chapter4/test.txt','r')
    # lines = file.readlines()
    # line = file.readline()
    content = file.read()
    print(content)
finally:
    if file:
        file.close()
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# 4.1.2 写

写文件时，操作系统往往不会立刻把数据写入磁盘，而是放到内存缓存起来，空闲的时候再慢慢写入。

path = './chapter4/test.txt'
content = 'Nihao'
try:
    f = open(path,'a')
    f.write(content)
finally:
    f.close()
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# 4.1.3 open 方法

模式

  • w
  • r
  • a 追加

# 4.2 Numpy

# 4.2.1 读写 csv、txt 文件

loadtxt，注意分隔符、编码等问题

import numpy as np
path = './chapter4/test.csv'
csv = np.loadtxt(path, delimiter=',')
print(csv)
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import numpy as np
data = np.ones((3,3))
np.savetxt(fname='./chapter4/write.csv',X=data,delimiter=',',encoding='utf-8')
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# 4.2.2 读写二进制文件

save

import numpy as np
arr = np.arange(10).reshape(2,5,1)
np.save('./chapter4/arr.npy', arr)
res = np.load('./chapter4/arr.npy')
print(res)
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# 4.2.3 读写.dat多维数据文件

import numpy as np

fileName = './chapter4/data.dat'
data = np.arange(30).reshape(5,2,3)
data.tofile(fileName,sep=',',format='%d')

newData = np.fromfile(fileName, dtype=np.int64, sep=',')
print(newData)
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# 4.3 Pandas

处理 csv 文件

import pandas as pd
df = pd.read_csv('./chapter4/test.csv', header=None, delimiter=',')
df.to_csv('./chapter4/pandas_test.csv')
df.head()
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处理 xlxs 文件

import pandas as pd
excel = pd.read_excel('./chapter4/table.xlsx', sheet_name='Sheet1', header=0)
excel.to_excel('./chapter4/pandas_table.xlsx',sheet_name='Sheet1')
excel.head()
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五、Numpy