python筛选出csv满足某条件的行,如何在csv文档中找到特定的行在python

What I'm trying to do is read into a csv document and find all values in the SN column > 20 and make a new file with only the rows with SN > 20.

I know that I need to do:

Read the original File

Open a new file

Iterate over rows of the original file

What I've been able to do is find the rows that have a value of SN > 20

import csv

import os

os.chdir("C:\Users\Robert\Documents\qwe")

with open("gdweights_feh_robert_cmr.csv",'rb') as f:

reader = csv.reader(f, delimiter= ',')

zerovar = 0

for row in reader:

if zerovar==0:

zerovar = zerovar + 1

else:

sn = row [11]

zerovar = zerovar + 1

x = float(sn)

if x > 20:

print x

So my question is how do I take the rows with SN > 20 and turn it into a new file?

解决方案

Save the data in a list, then write the list to a file.

import csv

import os

os.chdir(r"C:\Users\Robert\Documents\qwe")

output_ary = []

with open("gdweights_feh_robert_cmr.csv",'rb') as f:

reader = csv.reader(f, delimiter= ',')

zerovar = 0

for row in reader:

if zerovar==0:

zerovar = zerovar + 1

else:

sn = row [11]

zerovar = zerovar + 1

x = float(sn)

if x > 20:

print x

output_ary.append(row)

with open("output.csv",'w') as f2:

for row in output_ary:

for item in row:

f2.write(item + ",")