How to convert list to 20 column array

Question

I am making a program that takes a text file that looks something like this:

1
0
1
1
1

and converts it into a list:

['1','0','1','1','1']

The file has 400 lines so I want to convert it into an array that's 20 columns by 20 rows.

`I am making a program` can you show what you have made so far — Devesh Kumar Singh, Jul 05 '19 at 08:05
What do you plan to do with this data once you have it in your 20 by 20 structure? Would it be worth considering numpy? — Dan, Jul 05 '19 at 08:08

score 5 · Accepted Answer · answered Jul 05 '19 at 08:06

5

just use slicing to chunk it every 20 entries:

lines = [*range(1,401)]

rows_cols = [lines[i:i + 20] for i in range(0, len(lines), 20)]

answered Jul 05 '19 at 08:06

Adam.Er8

12,675
3
26
38

note: [numpy.reshape](https://docs.scipy.org/doc/numpy/reference/generated/numpy.reshape.html) does this efficiently in a single readable function call, if you're gonna do some numeric computations with it... – Adam.Er8 Jul 05 '19 at 08:10
+1 for the one-liner solution! Can you write it as an addition/edit in a less pythonic way so it is easier to understand for python beginners? – M.K Jul 05 '19 at 08:27

sahasrara62 · Answer 2 · 2019-07-05T08:15:26.077

this is save the character in 20 column, if in case no of rows are not multple of 20, it will create a list less element than 20 and add it in main list

solu =[]
leng = 20
with open('result.txt','r') as f:
    sol = f.readlines()
    tmp = []
    for i in sol:
        if len(tmp)<leng:
            tmp.append(i.strip('\n'))
        else:
            print(tmp)
            solu.append(tmp)
            tmp=[]
    solu.append(tmp)



print(solu)

score 0 · Answer 3 · answered Jul 05 '19 at 08:09

Detect characters one by one counting at the same time how many characters you detected. There are two cases one when you detect the character and the counter is less than 20 and the other one when you detect the newline character for which you don't update the counter. Therefore in the first case the detected character should be assigned to the list(updating at the same time the column variable) while on the other case you just skip the newline and you continue with the next character of the text file if the counter is less than 20. In case the counter is 20 you just simply update the variable which represents the lines of the list.

How to convert list to 20 column array

3 Answers3