如何在Python中输入n定义n阶矩阵？现有代码无法实现该需求

Hey there! Let's get this sorted—your current code is only generating a one-dimensional list, which is why it can't create an n-order matrix (a 2D structure with n rows and n columns). Let's break down the problem and fix it.

First, let's recap your original code to see why it's not working:

num_array = list() 
num = input("Enter how many elements you want:") 
print('Enter numbers in array: ') 
for i in range(int(num)): 
    n=input("num :") 
    num_array.append(int(n)) 
print('ARRAY: ',num_array)

This code just shoves all your input numbers into a single list—so if you enter 4 for the number of elements, you get a list like [1,2,3,4] instead of a 2x2 matrix like [[1,2],[3,4]].

How to Make an n-Order Matrix #

An n-order matrix is a list of lists: each sublist represents a row, and each row has exactly n elements. We'll use nested loops to build this structure step by step.

Working Code with Explanations #

# Start with an empty matrix (this will hold our rows)
matrix = []

# First, get the order of the matrix (n)
n_input = input("Enter the order of your matrix (n): ")

# Add quick validation to avoid crashes from bad input
try:
    n = int(n_input)
    if n <= 0:
        print("Whoops, please enter a positive whole number!")
        exit()
except ValueError:
    print("Oops, that's not a valid integer—try again!")
    exit()

print(f"\nGreat! Now enter {n} numbers for each of the {n} rows:")

# Build the matrix with nested loops
for row_num in range(n):
    # Create an empty list for this row
    current_row = []
    print(f"\nRow {row_num + 1}:")
    for col_num in range(n):
        element = input(f"Enter element {col_num + 1}: ")
        # Make sure the input is a number
        try:
            current_row.append(int(element))
        except ValueError:
            print("That's not a valid number—let's start over!")
            exit()
    # Add the finished row to our matrix
    matrix.append(current_row)

# Print the final matrix nicely
print("\nHere's your n-order matrix:")
for row in matrix:
    print(row)

What's Happening Here? #

• The outer loop runs n times—once for each row in the matrix.
• For each row, we create a new empty list (current_row) and use the inner loop to collect n elements for that row.
• Once a row is full, we add it to the main matrix list.
• We added input validation to handle cases where someone enters a non-integer or negative number, so your program won't crash unexpectedly.

A More Concise Version (List Comprehension) #

If you prefer shorter code, you can use Python's list comprehension to do the same thing in fewer lines:

try:
    n = int(input("Enter the order of your matrix (n): "))
    if n <= 0:
        raise ValueError
except ValueError:
    print("Please enter a positive integer!")
    exit()

# Use nested list comprehension to build the matrix
matrix = [[int(input(f"Row {i+1}, Element {j+1}: ")) for j in range(n)] for i in range(n)]

# Print the result
print("\nYour n-order matrix:")
for row in matrix:
    print(row)

This does exactly the same thing as the nested loop version—it's just a more compact way to write it.

内容的提问来源于stack exchange，提问作者Patrick Bro