Data transformation - Python

Question

I have the data in the following format (in a csv file):

a b c
b
a
a c d
b c
b c

I would like to covert the above data to the following format (list):

[['a', 'b', 'c'],
 ['b'],
 ['a'],
 ['a', 'c', 'd'],
 ['b', 'c'],
 ['b', 'c']]

I have done this so far:

import csv

fileName = "toydataset.csv"

data = open(fileName, 'r')
reader = csv.reader(data)
allRows = [row for row in reader]
allRows

But, the output looks like this:

[['a', 'b', 'c'],
 ['b', '', ''],
 ['a', '', ''],
 ['a', 'c', 'd'],
 ['b', 'c', ''],
 ['b', 'c', '']]

How do I remove those null values from the list so the output looks like this?

[['a', 'b', 'c'],
 ['b'],
 ['a'],
 ['a', 'c', 'd'],
 ['b', 'c'],
 ['b', 'c']]

Aftnix · Accepted Answer · 2015-12-04 03:31:56Z

3

In [8]: l
Out[8]: 
[['a', 'b', 'c'],
 ['b', '', ''],
 ['a', '', ''],
 ['a', 'c', 'd'],
 ['b', 'c', ''],
 ['b', 'c', '']]

In [9]: [ filter(None, a) for a in l]
Out[9]: [['a', 'b', 'c'], ['b'], ['a'], ['a', 'c', 'd'], ['b', 'c'], ['b', 'c']]

answered Dec 4, 2015 at 3:31

Aftnix

4,6396 gold badges29 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

snakes_on_a_keyboard · Accepted Answer · 2015-12-04 03:41:44Z

2

Here's an alternative. If you're in to that sort of thing.

import csv


def clean_item(item):
    res = [x for x in item if x]
    return res


def main():
    # PEP-8!
    file_name = "toydataset.csv"
    with open(file_name, 'r') as data: # don't corrupt your data!
        reader = csv.reader(data)
        # PEP-8!
        all_rows = [row for row in reader if row]
        print(all_rows)


if __name__ == '__main__':
    main()

edited Dec 4, 2015 at 3:41

answered Dec 4, 2015 at 3:34

snakes_on_a_keyboard

8844 silver badges8 bronze badges

Comments

Iron Fist · Accepted Answer · 2015-12-04 05:31:26Z

0

You can also do it without using any built-in method:

>>> l
[['a', 'b', 'c'], ['b', '', ''], ['a', '', ''], ['a', 'c', 'd'], ['b', 'c', ''], ['b', 'c', '']]
>>> [[i for i in j if i] for j in l]
    [['a', 'b', 'c'], ['b'], ['a'], ['a', 'c', 'd'], ['b', 'c'], ['b', 'c']]

answered Dec 4, 2015 at 5:31

Iron Fist

11k2 gold badges21 silver badges36 bronze badges

Collectives™ on Stack Overflow

Data transformation - Python

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related