How to read a csv file into a multidimensional list in Python

November 18, 2022

I’m trying to read a csv file into a multidimensional list with 52 rows and 7 columns. Currently it’s only displaying me the last line as 52 rows of the csv file.

I am pretty sure there is something wrong in my readfile function but I couldn’t figure it out where I’m making the mistake.

Here is my code:

rows = 52
cols = 7

def readFile():

  matrix = []

  file = open("rainfall.csv","r")
  for line in file:
    data = line.split(",")

  for row in range(rows):
    matrix.append([])
    for col in range(cols):
        matrix[row].append(data[col])
  
  return matrix
      
def display(matrix):
  for counter in matrix:
    for values in counter:
      print(values, end=" ")
    print()

matrix = readFile()
display(matrix)

Here is the output:

8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0 
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0
8 25 1 6 21 23 0

I have the following csv file:

0,0,30,2,21,13,23
29,3,29,30,7,8,25
26,5,26,13,4,13,4
22,30,13,15,15,0,2
3,12,11,10,17,0,15
8,13,11,24,30,24,27
22,18,2,29,11,13,18
15,1,29,23,18,7,0
23,27,3,7,13,14,28
6,25,24,14,20,23,5
24,29,26,22,0,9,18
22,27,22,20,24,29,21
23,13,14,4,13,1,21
25,21,21,6,28,17,19
4,6,11,10,21,1,5
11,7,22,11,10,24,15
25,11,23,3,23,8,3
22,23,0,29,15,12,5
21,11,18,22,1,4,3
11,10,3,1,30,14,22
2,16,10,2,12,9,9
2,29,17,16,13,18,7
22,15,27,19,6,26,11
21,7,18,4,14,14,2
6,30,12,4,26,22,11
21,16,14,11,28,20,3
19,10,22,18,30,9,27
8,15,17,4,11,16,6
19,17,16,6,18,18,6
2,15,3,25,27,16,11
15,5,26,24,24,30,5
15,11,16,22,14,23,28
25,6,7,20,26,18,16
5,5,21,22,24,16,5
6,27,11,8,24,1,16
28,4,1,4,3,19,24
19,3,27,14,12,24,0
6,3,26,15,15,22,26
18,5,0,14,15,7,26
10,5,12,22,8,7,11
11,1,18,29,6,9,26
3,23,2,21,29,15,25
5,7,1,6,15,18,24
28,11,0,6,28,11,26
4,28,9,24,11,13,2
6,2,14,18,20,21,1
20,29,22,21,11,14,20
28,23,14,17,25,3,18
6,27,6,20,19,5,24
25,3,27,22,7,12,21
12,22,8,7,0,11,8
8,25,1,6,21,23,0

>Solution :

Use the built-in csv module:

import csv
from pprint import pprint

with open('input.csv', newline='') as f:
    reader = csv.reader(f)
    data = [[int(x) for x in line] for line in reader]

pprint(data)

Output:

[[0, 0, 30, 2, 21, 13, 23],
 [29, 3, 29, 30, 7, 8, 25],
 [26, 5, 26, 13, 4, 13, 4],
 [22, 30, 13, 15, 15, 0, 2],
 [3, 12, 11, 10, 17, 0, 15],
 [8, 13, 11, 24, 30, 24, 27],
 [22, 18, 2, 29, 11, 13, 18],
 [15, 1, 29, 23, 18, 7, 0],
 [23, 27, 3, 7, 13, 14, 28],
 [6, 25, 24, 14, 20, 23, 5],
 [24, 29, 26, 22, 0, 9, 18],
 [22, 27, 22, 20, 24, 29, 21],
 [23, 13, 14, 4, 13, 1, 21],
 [25, 21, 21, 6, 28, 17, 19],
 [4, 6, 11, 10, 21, 1, 5],
 [11, 7, 22, 11, 10, 24, 15],
 [25, 11, 23, 3, 23, 8, 3],
 [22, 23, 0, 29, 15, 12, 5],
 [21, 11, 18, 22, 1, 4, 3],
 [11, 10, 3, 1, 30, 14, 22],
 [2, 16, 10, 2, 12, 9, 9],
 [2, 29, 17, 16, 13, 18, 7],
 [22, 15, 27, 19, 6, 26, 11],
 [21, 7, 18, 4, 14, 14, 2],
 [6, 30, 12, 4, 26, 22, 11],
 [21, 16, 14, 11, 28, 20, 3],
 [19, 10, 22, 18, 30, 9, 27],
 [8, 15, 17, 4, 11, 16, 6],
 [19, 17, 16, 6, 18, 18, 6],
 [2, 15, 3, 25, 27, 16, 11],
 [15, 5, 26, 24, 24, 30, 5],
 [15, 11, 16, 22, 14, 23, 28],
 [25, 6, 7, 20, 26, 18, 16],
 [5, 5, 21, 22, 24, 16, 5],
 [6, 27, 11, 8, 24, 1, 16],
 [28, 4, 1, 4, 3, 19, 24],
 [19, 3, 27, 14, 12, 24, 0],
 [6, 3, 26, 15, 15, 22, 26],
 [18, 5, 0, 14, 15, 7, 26],
 [10, 5, 12, 22, 8, 7, 11],
 [11, 1, 18, 29, 6, 9, 26],
 [3, 23, 2, 21, 29, 15, 25],
 [5, 7, 1, 6, 15, 18, 24],
 [28, 11, 0, 6, 28, 11, 26],
 [4, 28, 9, 24, 11, 13, 2],
 [6, 2, 14, 18, 20, 21, 1],
 [20, 29, 22, 21, 11, 14, 20],
 [28, 23, 14, 17, 25, 3, 18],
 [6, 27, 6, 20, 19, 5, 24],
 [25, 3, 27, 22, 7, 12, 21],
 [12, 22, 8, 7, 0, 11, 8],
 [8, 25, 1, 6, 21, 23, 0]]