在循环中迭代 python，分配 var 中的所有元素

Question

I wrote a function, it takes a password and encrypt it. Password: "verylongpassword2021" The idea is to create a square matrix, if missing letters, will be added "x".

Password is displayed as:

[['v' 'e' 'r' 'y' 'l']
 ['o' 'n' 'g' 'p' 'a']
 ['s' 's' 'w' 'o' 'r']
 ['d' '2' '0' '2' '1']
 ['x' 'x' 'x' 'x' 'x']]

Encrypted password read by column, from up-down. Password encrypted will be displayed as:

"vosdxens2xrgw0xypo2xlar1x".

I am having a hard time to assign it to a var. When I print the var I receive [array('v', dtype='<U1'), array('o', dtype='<U1'), array('s', dtype='<U1'), array('d', dtype='<U1'), array('x', dtype='<U1'), array('e', dtype='<U1'), array('n', dtype='<U1'), array('s', dtype='<U1'), array('2', dtype='<U1'), array('x', dtype='<U1'), array('r', dtype='<U1'), array('g', dtype='<U1'), array('w', dtype='<U1'), array('0', dtype='<U1'), array('x', dtype='<U1'), array('y', dtype='<U1'), array('p', dtype='<U1'), array('o', dtype='<U1'), array('2', dtype='<U1'), array('x', dtype='<U1'), array('l', dtype='<U1'), array('a', dtype='<U1'), array('r', dtype='<U1'), array('1', dtype='<U1'), array('x', dtype='<U1')]

Do you know what I am doing wrong here? I am facing the issue with the encrypted_matrix_password = [] when I print it.

import numpy as np
import math

def encrypt_matrix(password):
    len_password = len(password)
    n_matrix = math.ceil(pow(len_password, 0.5))

    # turn password into a list, by splitting each letter
    tokens = list(password)

    # add "X" to tokens until == 4 x4
    while len(tokens) < n_matrix ** 2:
        tokens.append("x")
    tokens_np_array = np.array(tokens)

    # create matrix n_matrix **2, write each character in matrix, starting from up row left, to right
    tokens_n_matrix = np.reshape(tokens_np_array, (n_matrix, n_matrix))
    print(tokens_n_matrix)

    # read matrix by columns starting up down
    read_matrix = tokens_n_matrix.copy(order="F")

    encrypted_matrix_password = []
    for char in np.nditer(read_matrix):
        print(char, end="")
        encrypted_matrix_password.append(char)

    # return encrypted_matrix_password
    print(encrypted_matrix_password)

    enc_mat = encrypt_matrix("verylongpassword2021")

Answer 1

See if the following changes help you.

import numpy as np
import math


def encrypt_matrix(password):
    len_password = len(password)
    n_matrix = math.ceil(pow(len_password, 0.5))

    # turn password into a list, by splitting each letter
    tokens = list(password)

    # add "X" to tokens until == 4 x4
    ##################################################################################
    # Not needed to use a loop, you know for sure how many missing characters you have
    # while len(tokens) < n_matrix ** 2:
    #     tokens.append("x")
    ##################################################################################
    tokens = tokens + ['x']*((n_matrix**2) - len(tokens))

    tokens_np_array = np.array(tokens)

    # create matrix n_matrix **2, write each character in matrix, starting from up row left, to right
    tokens_n_matrix = np.reshape(tokens_np_array, (n_matrix, n_matrix))
    print(tokens_n_matrix)
    # Output
    # [['v' 'e' 'r' 'y' 'l']
    #  ['o' 'n' 'g' 'p' 'a']
    #  ['s' 's' 'w' 'o' 'r']
    #  ['d' '2' '0' '2' '1']
    #  ['x' 'x' 'x' 'x' 'x']]

    # read matrix by columns starting up down
    read_matrix = tokens_n_matrix.copy(order="F")

    encrypted_matrix_password = ''  # use a string instead of a list 
    # for char in np.nditer(read_matrix):
    #     print(char, end="")
    #     encrypted_matrix_password.append(char)

    # Based on what @hpaulj commented
    for col in range(0, read_matrix.shape[1]):
        for row in range(0, read_matrix.shape[0]):
            encrypted_matrix_password += read_matrix[row, col]
    # return encrypted_matrix_password
    print(encrypted_matrix_password)
    # output
    # vosdxens2xrgw0xypo2xlar1x


enc_mat = encrypt_matrix("verylongpassword2021")

Answer 2

I've shorted your code. I padded the string with one expression, not a loop. And I "read out" the matrix by columns (order 'F'), and created a join string directly. No need to explicitly iterate. The ravel performs the copy('F') and converts it to 1d.

def encrypt_matrix(password):
    len_password = len(password)
    n_matrix = np.ceil(pow(len_password, 0.5)).astype(int)
    # pad string
    password += "x"*(n_matrix**2-len(password))
    # turn password into a list, by splitting each letter
    tokens = list(password)

    tokens_n_matrix = np.reshape(tokens, (n_matrix, n_matrix))
    print(tokens_n_matrix)
    encrypted_password=''.join(tokens_n_matrix.ravel(order='F'))
    return encrypted_password
    
In [11]: encrypt_matrix("verylongpassword2021")
[['v' 'e' 'r' 'y' 'l']
 ['o' 'n' 'g' 'p' 'a']
 ['s' 's' 'w' 'o' 'r']
 ['d' '2' '0' '2' '1']
 ['x' 'x' 'x' 'x' 'x']]
Out[11]: 'vosdxens2xrgw0xypo2xlar1x'

This may help visualize the action:

In [14]: x = np.arange(12).reshape(3,4)
In [15]: x
Out[15]: 
array([[ 0,  1,  2,  3],
       [ 4,  5,  6,  7],
       [ 8,  9, 10, 11]])
In [16]: x.ravel()
Out[16]: array([ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11])
In [17]: x.ravel(order='F')
Out[17]: array([ 0,  4,  8,  1,  5,  9,  2,  6, 10,  3,  7, 11])
In [25]: np.arange(12).reshape(4,3, order='F').ravel(order='C')
Out[25]: array([ 0,  4,  8,  1,  5,  9,  2,  6, 10,  3,  7, 11])