Define matrix in python

Question

Define matrix in python

Asked 6 years ago

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I need to create a matrix and fill it with random values (randint(0,9)), except in equal rows and columns. For example, in this way:

   A| B| C| D| E
A  x| 2| 1| 4| 2 
B  1| x| 1| 1| 2
C  5| 1| x| 4| 3
D  8| 2| 1| x| 2
E  5| 4| 1| 4| x

I’ve done this before:

from random import randint


def matrix():

    n=5 
    m=10

    matrixC = []
    value = (randint(0,9))

    #adicionar esse valores à matriz gerada
    for i in range(0, n):
        for j in range(0, n):
            if i != j:
                matrizC.append[[random.random() for i in range(n)] for j in range(n)]
            else:
                matrizC.append("x")

[UPDATE]

Following the directions I have this:

from random import randint

def matriz():
    #pedir o n
    n=5
    matriz = []  #declaração da matriz

    n_col=1
    n_lin=1

    for n_lin in range(n):
        linha = [] # cria uma linha para a matriz
        for n_col in range(n):
            if n_lin==n_col:
                linha.append('x')               
            else:
                linha.append(randint(1,9))

    matriz.append(linha)

    n_col=1
    n_lin=1 

    for n_lin in range(n):
        for n_col in range(n):
            print(matriz[n_lin][n_col], end='\t')

In the 3rd go I print the matrix, but when compiling I get no results.

There doesn’t seem to be anything wrong with the question - there is the initial code of the A.P., which has some parts missing, and an answer may guide it in the right direction.

– jsbueno

2018/11/19 at 15:17
Elaine, would [Dit] be your post adding a brief explanation of what went wrong or what did not correspond to the expectation in the code you tried? The post started well, with relevant details, but lacked a description of where exactly is the problem, which is precisely the doubt of programming in site scope. It ended up being a "question without question", but I believe that a simple edition complementing solve.

– Bacco

2018/11/19 at 16:04
That’s all your code? you know that in Python there is no special named function that is called automatically - rather that the program runs from start to finish, and functions need to be called. To see any result - even if it is not what you expect there, you have to call the function `matrix() in the module body.

– jsbueno

2018/11/20 at 12:52

1 answer

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by nosklo • **5,801** points · Answer 1 · 2018-11-19T19:53:43+00:00

The problem is that you are mixing two techniques. One way to do it is by using the forstructured one on each line:

matriz = []
for n_lin in range(5):
    linha = [] # cria uma linha para a matriz
    for n_col in range(5):
        if n_lin == n_col:
            linha.append('x')
        else:
            linha.append(randint(0, 9))
    matriz.append(linha)

The other way is to put everything in one line, the famous "list understanding":

matriz = [['x' if x == y else randint(0, 9) for x in range(5)] for y in range(5)]