Reshape 1D List to 2D List -Python

Question

I have the following list:

a = ['2', '3', '4', '7', '5']

I want to transform to a 2D matrix knowing that I have 4 columns, I do not consider rows here

I want to achieve this without repeating the items, just fill the rest with None or empty space as follows:

New_a = [['2', '3', '4', '7'],
         ['5', None, None, None]]

I tried to reshape it using reshape function, but it did not work, because the target matrix is not consistent.

I also tried (resize function). It did not work because it repeat the items once there are some gaps at the end.

Asked By: jamal manssour

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Source

Answer 1

New_a = []
a = ['2', '3', '4', '7', '5']
for i in range(0,len(a),4) :
    New_a.append(a[i:i+4])
if len(New_a[-1]) != 4 :
    New_a[-1] += [None]*(4-len(New_a[-1])) 
print(New_a)

output :-

[['2', '3', '4', '7'], ['5', None, None, None]]

This should work for different lengths of the 1d array a

You can also use reisze() function of numpy array but it will fill your array with empty strings instead of None.

Example :-

a = ['2', '3', '4', '7', '5']
a1=np.array(a)
a1.resize((int(np.ceil(len(a)/4)),4))

a1 will look like this:-

array([['2', '3', '4', '7'],
       ['5', '', '', '']], dtype='<U1')

Answered By: Nehal Birla

Reshape 1D List to 2D List -Python

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