Convert from CSV to array in Python

Question

I have a CSV file containing the following.

0.000264,0.000352,0.000087,0.000549
0.00016,0.000223,0.000011,0.000142
0.008853,0.006519,0.002043,0.009819
0.002076,0.001686,0.000959,0.003107
0.000599,0.000133,0.000113,0.000466
0.002264,0.001927,0.00079,0.003815
0.002761,0.00288,0.001261,0.006851
0.000723,0.000617,0.000794,0.002189

I want convert the values into an array in Python and keep the same order (row and column). How I can achieve this?

I have tried different functions but ended with error.

what is error? and how are you attempting to read the csv file? are you using the `csv` module? — Tom Myddeltyn, May 11 '16 at 21:53
Questions seeking debugging help (**"why isn't this code working?"**) must include the desired behavior, *a specific problem or error* and *the shortest code necessary* to reproduce it **in the question itself**. Questions without **a clear problem statement** are not useful to other readers. See: [How to create a Minimal, Complete, and Verifiable Example](http://stackoverflow.com/help/mcve). — MattDMo, May 11 '16 at 22:02
Does your CSV file actually contain the parentheses `( )`? If so, it's not valid CSV. How was the file generated? — MattDMo, May 11 '16 at 22:05
@MattDMo dont have parathesis, do have any idea how I can convert from cvs to array, keep the same orden — Edian Franklin Franco de los S, May 11 '16 at 22:13
Are you trying to return a list of lists, then? like `a = [[123, 234, 345], [456, 567, 678]]` but with your numbers instead? — CodeJockey, May 11 '16 at 22:17
If you don't have the parens the csv lib will do the parsing so where is the problem? — Padraic Cunningham, May 11 '16 at 22:24

score 19 · Accepted Answer · answered May 11 '16 at 22:22

You should use the csv module:

import csv

results = []
with open("input.csv") as csvfile:
    reader = csv.reader(csvfile, quoting=csv.QUOTE_NONNUMERIC) # change contents to floats
    for row in reader: # each row is a list
        results.append(row)

This gives:

[[0.000264, 0.000352, 8.7e-05, 0.000549], 
[0.00016, 0.000223, 1.1e-05, 0.000142], 
[0.008853, 0.006519, 0.002043, 0.009819], 
[0.002076, 0.001686, 0.000959, 0.003107], 
[0.000599, 0.000133, 0.000113, 0.000466], 
[0.002264, 0.001927, 0.00079, 0.003815], 
[0.002761, 0.00288, 0.001261, 0.006851], 
[0.000723, 0.000617, 0.000794, 0.002189]]

James Buck · Answer 2 · 2016-05-11T22:29:51.520

3

If your file doesn't contain parentheses

with open('input.csv') as f:
    output = [float(s) for line in f.readlines() for s in line[:-1].split(',')]
    print(output);

edited May 11 '16 at 22:29

answered May 11 '16 at 22:14

James Buck

1,640
9
13

Yes, I the original float, one per cell in the array. @MattDMo – Edian Franklin Franco de los S May 11 '16 at 22:28

score 2 · Answer 3 · answered May 11 '16 at 22:22

The csv module was created to do just this. The following implementation of the module is taken straight from the Python docs.

import csv 
with open('file.csv','rb') as csvfile: 
    reader = csv.reader(csvfile, delimiter=',', quotechar='|') 
    for row in reader:
        #add data to list or other data structure

The delimiter is the character that separates data entries, and the quotechar is the quotechar.

Convert from CSV to array in Python

3 Answers3

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