How to print the output of a defined function

[bshoushtarian]

How to print the output of make_matrix function defined in the following code:

from typing import List, Callable
Matrix = List[List[float]]


def make_matrix(num_rows: int,
                num_cols: int,
                entry_fn: Callable[[int, int], float]) -> Matrix:
    """Returns a num_rows x num_cols matrix whose (i,j)-th entry is entry_fn(i, j) """
    return [[entry_fn(i, j)  # given i, create a list
            for j in range(num_cols)]  # [entry_fn(i, 0), ... ]
            for i in range(num_rows)]  # create one list for each i

Larz60+ write Sep-07-2022, 08:05 PM:
As mentioned by menator01 in next post:
Please post all code, output and errors (it it's entirety) between their respective tags. Refer to BBCode help topic on how to post. Use the "Preview Post" button to make sure the code is presented as you expect before hitting the "Post Reply/Thread" button.
Fixed for you this time.

[menator01]

Please use tags when posting code.

To print out a return from a function you can do this

def myfunc(arg1, arg2, arg3):
    return f'Arg1 -> {arg1}, Arg2 -> {arg2}, List of args -> {arg3}'

print(myfunc('Argument 1', 'Argument 2',[1,2,3,4,5]))

Output:
Arg1 -> Argument 1, Arg2 -> Argument 2, List of args -> [1, 2, 3, 4, 5]

[deanhystad]

What's wrong with using print?

from typing import List, Callable

Matrix = List[List[float]]


def make_matrix(
    num_rows: int,
    num_cols: int,
    entry_fn: Callable[[int, int], float] = lambda *args: 0,
) -> Matrix:
    """Returns a num_rows x num_cols matrix whose (i,j)-th entry is entry_fn(i, j)"""
    return [
        [
            entry_fn(i, j) for j in range(num_cols)  # given i, create a list
        ]  # [entry_fn(i, 0), ... ]
        for i in range(num_rows)
    ]  # create one list for each i


print(make_matrix(3, 5))

Output:
[[0, 0, 0, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0]]

Or are you looking for something pretty? This is easy:

for row in make_matrix(3, 5):
    print(row)

Output:
[0, 0, 0, 0, 0]
[0, 0, 0, 0, 0]
[0, 0, 0, 0, 0]

But it will likely be ragged.

for row in make_matrix(3, 5, lambda x, y: "X"*(x+y))):
    print(row)

Output:
['', 'X', 'XX', 'XXX', 'XXXX']
['X', 'XX', 'XXX', 'XXXX', 'XXXXX']
['XX', 'XXX', 'XXXX', 'XXXXX', 'XXXXXX']

There are packages that will print a pretty table.

from tabulate import tabulate

print(tabulate(make_matrix(3, 5, lambda x, y: "X" * (x + y)), tablefmt="fancy_grid"))

Output:
╒════╤═════╤══════╤═══════╤════════╕
│    │ X   │ XX   │ XXX   │ XXXX   │
├────┼─────┼──────┼───────┼────────┤
│ X  │ XX  │ XXX  │ XXXX  │ XXXXX  │
├────┼─────┼──────┼───────┼────────┤
│ XX │ XXX │ XXXX │ XXXXX │ XXXXXX │
╘════╧═════╧══════╧═══════╧════════╛

Or you could use numpy.

[bshoushtarian]

Hi deanhystad,

Thank you very much for your response. How is the following response, for example?

from typing import List, Callable
Matrix = List[List[float]]


def make_matrix(num_rows: int,
                         num_cols: int,
                         entry_fn: Callable[[int, int], float]) -> Matrix:

      """Returns a num_rows x num_cols matrix whose (i,j)-th entry is entry_fn(i, j) """
     return [[entry_fn(i, j)  # given i, create a list
                for j in range(num_cols)]  # [entry_fn(i, 0), ... ]
                for i in range(num_rows)]  # create one list for each i


print("X=", make_matrix(2, 3, lambda i, j: input("X["+str(i)+', '+str(j)+"]= ") if i != j else 1))

Sample output:

Output:
X[0, 1]= 2
X[0, 2]= 3
X[1, 0]= 4
X[1, 2]= 5
X= [[1, '2', '3'], ['4', 1, '5']]

Of course, this is not what I want to do!

Larz60+ write Sep-08-2022, 02:35 PM:
Please post all code, output and errors (it it's entirety) between their respective tags. Refer to BBCode help topic on how to post. Use the "Preview Post" button to make sure the code is presented as you expect before hitting the "Post Reply/Thread" button.

[deanhystad]

I might answer your question if you start wrapping posted code in Python tags so it can be read.