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I have a csv file with two columns. I am trying to read that second column from that csv file to a list in python . I referred to some of the ways in stackoverflow. I tried them, but I am getting an error.

noise_amp=[]         #an empty list to store the second column
with open('null_ch1_waveform_10mV.csv', 'rb') as rf:
    reader = csv.reader(rf, delimiter=';')
    for row in reader:
       noise_amp.extend([row[1]])

I am getting this error:

Traceback (most recent call last):
  File "J:/Ramu_Scripts/noise_script/source_code.py", line 58, in <module>
    noise_amp.extend([row[1]])
IndexError: list index out of range

My csv file is like

 1,2
 2,3
 3,4
 4,5
Ramanjaneyulu Gudipati
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    Can you provide some example of your csv data? – stamaimer Sep 07 '17 at 16:50
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    See the accepted answer to [**_When processing CSV data, how do I ignore the first line of data?_**](https://stackoverflow.com/questions/11349333/when-processing-csv-data-how-do-i-ignore-the-first-line-of-data) which shows how to process the data in a csv column. – martineau Sep 07 '17 at 17:24

3 Answers3

6

Try this :

import csv
noise_amp=[]         #an empty list to store the second column
with open('demo.csv', 'r') as rf:
    reader = csv.reader(rf, delimiter=',')
    for row in reader:
      noise_amp.append(row[1])

Use r or rb as open mode and delimiter be ,

bhansa
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2

The easiest solution i can think of, without using the builtin csv module* is the following:

with open(csv_file, 'r') as f:
    for row in f:
        second_data = row.split(',')[1]

Than you can do anything you want with it

* Not using the csv module isn't really pythonic, Take a look at it if you want clean code

Owlzy
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2

The following code works for me. I think its the issue with your delimiter. If yours is a normal csv file, then you need not use the delimiter argument. 

import csv
noise_amp=[]         
with open('glass.csv', 'r') as rf:
 reader = csv.reader(rf)
 for i in reader:
    noise_amp.extend([i[1]])
Christy Jacob
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