逐行读取csv文件

Question

I am using Python v2.7 (please don't ask me to use Python v3). I have a csv file, its content is like this:

name age gender height
John 30  male   180
Kate 23  female 166
...

I use csv module. I try to read the content row by row with the following code:

import csv

with open("data.csv", 'r') as data_file:
     reader = csv.reader(data_file, delimiter='\t')
     # ERROR: ValueError: need more than 2 values to unpack
     for name, age, gender, height in enumerate(reader):
         print name + ',' + age + ',' + gender + ',' + height

But I got error when run it:

ValueError: need more than 2 values to unpack

How to get rid of this error?

Answer 1

The issue that enumerate returns a tuple - item number and item itself. So it returns two elements, and you forces it to unpack 4 elements instead(check https://docs.python.org/2/library/functions.html#enumerate ). Try to transform it to:

for index, (name, age, gender, height) in enumerate(reader)

But actually I think you don't need enumerate function here since you don't use element index. If it won't work you can simply access a row by indexes as described in example in the doc: https://docs.python.org/2/library/csv.html#csv.reader

Answer 2

You are using enumerate() in the wrong way. Please see this for further information: https://docs.python.org/2.3/whatsnew/section-enumerate.html

Regarding your code, you can do the following:

import csv

with open("data.csv", 'r') as data_file:
   reader = csv.reader(data_file, delimiter='\t')       
   for row in reader:
     print ', '.join(row)

Answer 3

import csv

with open("data.csv", 'r') as data_file:
  data_file.readline() # Skip first line
  reader = csv.reader(data_file, delimiter=',')
  for name, age, gender, height in reader:
     print name + ',' + age + ',' + gender + ',' + height

yields

John, 30 , male  , 180
Kate, 23 , female, 166