读写csv文档

import csv
import codecs

s=[]
with open("port.csv","r")as f:
    for line in f.readlines():
        s.append(line)
    for lines in s:
        if ','in lines:
            lines=lines.split(',')
            print lines[0]
with open("port.csv",'r')as f:
    reader=csv.reader(f)
    for item in reader:
        print item
with open("test1.csv","w")as f:
    writer=csv.writer(f)
    writer.writerow(['1','200','2500'])
    writer.writerow(['250','300','5000','800'])

#读取txt文件，并将写入csv中
with open('test.csv','w')as fw:
    writer=csv.writer(fw)
    with open('test.txt','r')as fr:
        for line in fr.readlines():
            line=line.strip('\n')
            line=line.split(',')
            if line==['']:
                continue
            else:
                print(line)
                writer.writerow(line)