python_1_本地数据获取

1.文件读写示例：读写、文件指针移动

words = 'Winter is coming!'      #写入的数据

with open(r'..	estfilescompanies.txt','a+') as f:
    f.writelines('
')
    f.writelines(words)
    f.seek(0,0)                  #移动文件指针到文件开头
    cNames = f.readlines()

print(cNames)

2.批量文件处理示例：统计文件行数

ef countLines(fname):
    '统计文件里内容的行数'
    try:
        with open('..\testfiles\' + fname) as f:
            data = f.readlines()
    except FileNotFoundError:
        print(fname + 'does not exist')
    lens = len(data)
    print(fname + ' has ' + str(lens) +' lines')

files = ['data1.txt','data2.txt','data3.txt']
for fname in files:
    countLines(fname)

   改进：统计某文件夹下的各TXT文件行数

import os

def countLines(fname):
    '统计文件里内容的行数'
    try:
        with open(fname) as f:
            data = f.readlines()
    except FileNotFoundError:
        print(fname + 'does not exist')
    lens = len(data)
    print(fname.split('\')[1] + ' has ' + str(lens) +' lines')

path = '../testfiles'
for fname in os.listdir(path):
    if fname.endswith('.txt'):
        file_path = os.path.join(path,fname)
        countLines(file_path)
        

3.创建保存输出文件的目录

import os

if os.path.exists('./output'):
    shutil.rmtree('./output')     #如果存在非空的该目录，则删除该目录
os.mkdir('./output')              #创建所需的目录

dir()

help()