python文件读写-----csv的使用

 首先来看看原始的读取：

f= open(file,'r')
stat = f.readlines()
print(stat)

输出的结构是一个整体的列表。

['姓名,性别,年龄,爱好,人脉,学习\n', '0,8,0,9,0\n', '1,9,1,10,1\n', '2,10,4,11,2\n', '3,11,9,12,3\n', '4,12,16,13,4\n', '5,13,25,14,5\n', '6,14,36,15,6\n', '7,15,49,16,7\n', '8,16,64,17,8\n', '9,17,81,18,9\n', '10,18,100,19,10\n', '11,19,121,20,11\n'']

采用csv模块操作，能更方便的进行数据的操作：

with open(file,'r') as file:
    reader = csv.reader(file)
    lines = [line for line in reader]
    print(lines)

[['姓名', '性别', '年龄', '爱好', '人脉', '学习'], ['0', '8', '0', '9', '0'], ['1', '9', '1', '10', '1'], ['2', '10', '4', '11', '2'], ['3', '11', '9', '12', '3'], ['4', '12', '16', '13', '4'], ['5', '13', '25', '14', '5'], ['6', '14', '36', '15', '6']]

一、csv的写操作：

import csv
csvflie= open(file,'w',newline='')  #newline指的是文件的最后none--->\n
try:
    writer = csv.writer(csvfile)#构建一个写的对象
    print(type(writer))
    writer.writerow=(('姓名','行呗','学号'))#往里面写数据
    for i in range(10):
        writer.writerow=((i,i+1,i*i))#注意切记！无等号
    print('chengg')

except Exception as c:
    print(c)
    print('操作失败')

finally:
    csvfile.close()

1.1查看文件的大小

def get_size(path):
    file_size = os.path.getsize(path)
    print(file_size)

get_size(file)

二、csv文件的读取操作

方法一：用index索引重新写入

import csv
with open(file,'r') as file:
    reader = csv.reader(file)
    rows =[row for row in reader] #把reader遍历在一个列表中
    for line in rows:
        print(line)
        for index,i in enumerate(line):#把每个元素取出来
            with open(r'C:\Users\jeep-peng zhang\Desktop\demo.txt','a') as file_new:
                if index==len(line)-1:#换行
                    file_new.write(i+'\n')
                else:
                    file_new.write(i+' ')
                file_new.close()

方法二：

import csv
with open(file,'r') as file:
    reader = csv.reader(file)
    lines = [line for line in reader]#循环把他存在列表里面
    for result in lines:#把列表里面的东西循环出来
        line_str = ','.join(result)#用逗号隔开
        print(line_str)
        with open(r'C:\Users\jeep-peng zhang\Desktop\demo.txt','a') as new_file:
            # writer = csv.writer(new_file)
            # writer.row(line_str+'\n')
            new_file.write(line_str+'\n')