Converting list of lists into a matrix. (python 3)

Question

I got the following list of lists:

mat =  [['a,p,p,l,e'], ['a,g,o,d,o'], ['n,n,e,r,t'], ['g,a,T,A,C'], ['m,i,c,s,r'], ['P,o,P,o,P']]

As you can see, this list of lists doesn't function as a matrix properly.

How can I convert it to:

  mat = [['a','p','p','l','e'], ['a','g','o','d','o'], ['n','n','e','r','t'], ['g','a','T','A','C'], ['m','i','c','s','r'], ['P','o','P','o','P']]

such that if i operate mat[1][2] i get o

Answer 1

Here is a way to do it with list comprehension:

If we have a nested list like your example.

nested_list = [['a,p,p,l,e'], ['a,g,o,d,o'], ['n,n,e,r,t'], ['g,a,T,A,C'], ['m,i,c,s,r'], ['P,o,P,o,P']]

We would have to go through each item and split every item's string on the "," so ['a, p, p, l, e'] would be ['a', 'p', 'p', 'l', 'e'].

# New list
matrix = [item.split(",") for sublist in nested_list for item in sublist] 

print(matrix) 

The result will now be a matrix.

[['a', 'p', 'p', 'l', 'e'], 
 ['a', 'g', 'o', 'd', 'o'], 
 ['n', 'n', 'e', 'r', 't'], 
 ['g', 'a', 'T', 'A', 'C'], 
 ['m', 'i', 'c', 's', 'r'], 
 ['P', 'o', 'P', 'o', 'P']] 

This is the same as writing this:

matrix = []

for item in nested_list:
    for i in item:
        matrix.append(i.split(","))

print(matrix)

Have a look at this link about nested list comprehension

Answer 2

You could use something like this to convert it:

mat =  [['a,p,p,l,e'], ['a,g,o,d,o'], ['n,n,e,r,t'], ['g,a,T,A,C'], ['m,i,c,s,r'], ['P,o,P,o,P'
newMat = []

for i in mat:
    newMat.append(i[0].split(","))

print(newMat[1][2])