Creating lists from rows with different lengths in python

Question

I am trying to create a list for each column in python of my data that looks like this:

399.75833     561.572000000        399.75833     561.572000000  a_Fe I 399.73920 nm
399.78316     523.227000000        399.78316     523.227000000  
399.80799     455.923000000        399.80799     455.923000000  a_Fe I 401.45340 nm
399.83282     389.436000000        399.83282     389.436000000  
399.85765     289.804000000        399.85765     289.804000000

The problem is that each row of my data is a different length. Is there anyway to format the remaining spaces of the shorter rows with a space so they are all the same length?

I would like my data to be in the form:

list one= [399.75833, 399.78316, 399.80799, 399.83282, 399.85765]
list two= [561.572000000, 523.227000000, 455.923000000, 389.436000000, 289.804000000]
list three= [a_Fe, " ", a_Fe, " ", " "]

This is the code I used to import the data into python:

fh  = open('help.bsp').read()
the_list = []
for line in fh.split('\n'):
    print line.strip()
    splits = line.split()
    if  len(splits) ==1 and splits[0]== line.strip():
        splits = line.strip().split(',')
    if splits:the_list.append(splits)

sisanared · Accepted Answer · 2016-10-16 06:11:08Z

1

You need to use izip_longest to make your column lists, since standard zip will only run till the shortest length in the given list of arrays.

from itertools import izip_longest
with open('workfile', 'r') as f:
    fh = f.readlines()

# Process all the rows line by line
rows = [line.strip().split() for line in fh]
# Use izip_longest to get all columns, with None's filled in blank spots
cols = [col for col in izip_longest(*rows)]
# Then run your type conversions for your final data lists
list_one = [float(i) for i in cols[2]]
list_two = [float(i) for i in cols[3]]
# Since you want " " instead of None for blanks
list_three = [i if i else " " for i in cols[4]]

Output:

>>> print list_one
[399.75833, 399.78316, 399.80799, 399.83282, 399.85765]
>>> print list_two
[561.572, 523.227, 455.923, 389.436, 289.804]
>>> print list_three
['a_Fe', ' ', 'a_Fe', ' ', ' ']

edited Oct 16, 2016 at 6:11

answered Oct 16, 2016 at 5:45

sisanared

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Comments

cco · Accepted Answer · 2016-10-16 05:51:17Z

So, your lines are either whitespace delimited or comma delimited, and if comma delimited, the line contains no whitespace? (note that if len(splits)==1 is true, then splits[0]==line.strip() is also true). That's not the data you're showing, and not what you're describing.

To get the lists you want from the data you show:

with open('help.bsp') as h:
    the_list = [ line.strip().split() for line in h.readlines() ]
list_one = [ d[0] for d in the_list ]
list_two = [ d[1] for d in the_list ]
list_three = [ d[4] if len(d) > 4 else ' ' for d in the_list ]

If you're reading comma separated (or similarly delimited) files, I always recommend using the csv module - it handles a lot of edge cases that you may not have considered.

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