Python extra blank line in two ways by the content of the csv output writerow

the first method

Csv file is generated as follows have a plurality of blank lines

import csv

#python2可以用file替代open
with open("test.csv","w") as csvfile: 
    writer = csv.writer(csvfile)

    #先写入columns_name
    writer.writerow(["index","a_name","b_name"])
    #写入多行用writerows
    writer.writerows([[0,1,3],[1,2,3],[2,3,4]])

Add newline = '' parameters

#coding=utf-8
import csv

#python2可以用file替代open
with open("test.csv","wt",newline='') as csvfile: 
    writer = csv.writer(csvfile)
    #写入多行用writerows
    writer.writerows([["index","a_name","b_name"],[0,1,3],[1,2,3],[2,3,4]])

So it will not free the line.

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The second method:

First write csv file, and then read out to remove the blank line, and then write

with open('E:\\test.csv','wt')as fout:       #生成csv文件,有空行
    cout=csv.DictWriter(fout,list_attrs_head )
    cout.writeheader()
    cout.writerows(list_words)
with open('E:\\test.csv','rt')as fin:  #读有空行的csv文件，舍弃空行
    lines=''
    for line in fin:
        if line!='\n':
            lines+=line
with open('E:\\test.csv','wt')as fout:  #再次文本方式写入，不含空行
    fout.write(lines)