Python 。 用列表制作矩阵

Question

I want to make matrix with list

What I want to make is this following .

coll = ["AA","BB","CC","DD"]

What I want to make is this following .

matrix = [
    ["AA:AA","AA:BB","AA:CC","AA:DD"],
    ["BB:AA","BB:BB","BB:CC","BB:DD"],
    ["CC:AA","CC:BB","CC:CC","CC:DD"],
    ["DD:AA","DD:BB","DD:CC","DD:DD"],

]

I am newbie in Python ... Could someone give me how to do and with some references or explanation ?

Answer 1

The Pythonic way to implement this is a two-tier list comprehension.

coll = ["AA","BB","CC","DD"]
matrix = [
  ['%s:%s' % (a, b) for b in coll]
  for a in coll
]

Another way to put it that might be easier to understand is

matrix = []
for a in coll:
  row = []
  for b in coll:
    row.append('%s:%s' % (a, b))
  matrix.append(row)

but the result will be the same:

print(matrix)
[['AA:AA', 'AA:BB', 'AA:CC', 'AA:DD'],
 ['BB:AA', 'BB:BB', 'BB:CC', 'BB:DD'],
 ['CC:AA', 'CC:BB', 'CC:CC', 'CC:DD'],
 ['DD:AA', 'DD:BB', 'DD:CC', 'DD:DD']]

Answer 2

Actually I solved by my *easy and *shy way

coll = ["AA","BB","CC","DD"]

mat = [[0]*4 for i in range(4)]

i = j =0


for xx in coll :
    for yy in coll :
        mat[i][j] = xx + ':' + yy 
        j += 1
    i += 1
    j = 0

print(mat)

I appreciated with all guys.