Get only one column from CSV file in Python

Question

I'm trying to take a csv of three columns and n rows, and make just the elements of the first column into an iterable list. The problem I'm having is that it is taking a list that looks like this (in the code, "datalist"):

[
    ['56529.132', '16.9199', '0.152425'], ['56529.133', '16.4637', '0.127646'],
    ['56529.139', '16.4859', '0.12598'],  ['56529.139', '16.4011', '0.121806'],
    ['56529.147', '16.7835', '0.31821'],  ['56529.148', '16.3248', '0.179531'],
    ['56529.155', '16.3012', '0.146556'], ['56529.162', '16.1506', '0.174568'],
    ['56529.169', '16.1904', '0.180294'], ['56529.17', '16.0262', '0.164397'],
]

And isolating the first column into something that looks like:

56529.132
56529.133
56529.139
56529.139
56529.147
56529.148
56529.155
56529.162
56529.169
56529.17

In this second output, each individual character is an element of data all by itself, so that if I make it into a list like what I want, it looks like:

['5']
['6']
['5']
['2']
['9']
['.']
['1']
['3']
['2']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['3']
['3']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['3']
['9']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['3']
['9']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['4']
['7']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['4']
['8']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['5']
['5']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['6']
['2']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['6']
['9']
['5']
['6']
['5']
['2']
['9']
['.']
['1']
['7']

How could I fix this? I need a list with each of these elements "intact," so it looks like

[['56529.132'],['56529.133'],['56529.139'],...

My code so far:

def read_csvfile(filename):
    import csv
    with open(filename) as csvfile:
        reader = csv.reader(csvfile, delimiter='\t')
        datalist = list(reader)
    return datalist

in_confirm = read_csvfile('bin3test.csv')

def confirm_obs(in_confirm):

    for row in in_confirm:
        col1 = row[0]
        print(col1)


result = confirm_obs(in_confirm)

A bit of the data in the csv:

56529.132   16.9199 0.152425
56529.133   16.4637 0.127646
56529.139   16.4859 0.12598
56529.139   16.4011 0.121806
56529.147   16.7835 0.31821
56529.148   16.3248 0.179531
56529.155   16.3012 0.146556
56529.162   16.1506 0.174568
56529.169   16.1904 0.180294
56529.17    16.0262 0.164397

Answer 1

Given in_confirm (also datalist):

first_values = [ [x[0].split()[0]] for x in in_confirm ]

If you don't need the data structure to be mutable, it's better practice to use a tuple:

first_values = [ (x[0].split()[0],) for x in in_confirm ]

but yes, it would be better to fix the delimiter problem on read.

Answer 2

I would get the first row like this:

first_col = [row[0] for row in in_confirm]

And then I'd get the individual characters/digits with either of these two methods (not sure which one you need):

[x for item in first_col for x in item]
# ['5', '6', '5', '2', '9', '.', '1', '3', '2', '5', ...

[[x] for item in first_col for x in item]
# [['5'], ['6'], ['5'], ['2'], ['9'], ['.'], ...