Python Turtle - 尝试更新一个数组值会更新同一列表索引的所有值

Posted 2023-02-14

【中文标题】Python Turtle - 尝试更新一个数组值会更新同一列表索引的所有值

【英文标题】：Python Turtle -- Trying to update one array value updates all the values of the same list index

【发布时间】：2022-01-22 01:11:24

【问题描述】：

我正在编写一个程序，该程序根据输入的行数和列数绘制正方形网格，获取输入的行、列和颜色索引（来自颜色查找表的索引），然后绘制另一个正方形在具有指定颜色和位置的网格上。循环直到输入一个空值。

我为网格的颜色索引值创建了一个位图数组，每个嵌套列表代表一行正方形，每个正方形的初始值设置为 0。

我想在每次绘制新的颜色方块时更新数组中的单个值。

我尝试使用

更新数组中的值

bitmap[row_index][col_index] = clut_index 

在输入循环中，还有

bitmap[row][col] = colorindex

在绘制彩色方块的函数中。

每次，它不是更新数组中的一个值，而是用相同的列表索引更新数组中的所有值，以便每一行/列表最终都具有相同的值。

例如，一个输入

5 6

对于网格大小，以及

0 2 3 2 5 1 4 0 5

彩色方块的结果应该是

[[0, 0, 3, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1], [ 0, 0, 0, 0, 0, 0], [5, 0, 0, 0, 0, 0]]

但结果是

[[5, 0, 3, 0, 0, 1], [5, 0, 3, 0, 0, 1], [5, 0, 3, 0, 0, 1], [ 5, 0, 3, 0, 0, 1], [5, 0, 3, 0, 0, 1]]

方块在网格上绘制得很好，但位图列表没有正确更新。

如何一次只更新数组中的一个值？这是我的代码，我将有关位图数组的部分加粗。很抱歉这个程序很长而且相当混乱：

from turtle import *
from array import *

#inputting the number of rows and columns to make the grid
grid_dimensions = input("Please input the number of rows and number of columns, separated by a space:")
grid_list = grid_dimensions.split(" ")

rows = int(grid_list[0])
columns = int(grid_list[1])

# setting the window size as an aspect ratio of the rows and columns
# this is to make sure that each grid cell is a square
# window has a max size of 800 pixels
if rows > columns:
    window_w = (800/rows)*columns
    window_h = 800
elif rows < columns:
    window_w = 800
    window_h = (800/columns)*rows
else:
    window_w = 800
    window_h = 800

# creating window and coordinate grid
# coordinates are in pixels, grid is the same size as the window
setup(window_w, window_h)
setworldcoordinates(0, 0, window_w, window_h)

# setting the side length of the square as the size of each grid cell
square_length = window_w/columns

# creating a color look-up table of RGB color values
clut = [(1.0, 1.0, 1.0), (0.0, 0.0, 0.0), (1.0, 0.0, 0.0), (1.0, 1.0, 0.0), (0.0, 1.0, 0.0), (0.0, 1.0, 1.0), (0.0, 0.0, 1.0), (1.0, 0.0, 1.0)]

# creating a bitmap array of the color index value for each square in the grid
# populating the array by setting each value to zero
rowline = []
bitmap = []
for col in range(columns):
    rowline.append(0)
for row in range(rows):
    bitmap.append(rowline)

# moves the pen to the starting position of each square
def movepos(x, y):
    penup()
    setpos(x, y)
    pendown()

# draws the square based on the row and column positions on the grid
# uses the static square size
def drawsquare(row, col, square_size):
    movepos(col*square_size, row*square_size)
    for i in range(4):
        forward(square_size)
        left(90)

# calls the function to draw a square in a loop for the number of columns and rows
def drawgrid(row_number, col_number, square_size):
    for row in range(row_number):
        for col in range(col_number):
            drawsquare(row, col, square_size)

# "colors in the grid cell" by drawing a colored square at a specific row and column position
def colorpixel(row, col, colorindex, square_size):
    fillcolor(clut[colorindex])
    begin_fill()
    drawsquare(row, col, square_size)
    end_fill()

# drawing the initial empty grid
drawgrid(rows, columns, square_length)

# creates an empty list to put the input values into
# creates a starting value for the loop

# takes the first set of row, column, and color input values to draw a colored square
index_input = input("Please input a row number, a column number, and a color number separated by spaces, then hit Enter. To finish coloring, hit Enter without entering any values: ")

# loops to draw multiple colored squares
# loop breaks when an empty value is entered
while index_input:
    input_list = index_input.split(" ")
 
    row_index = int(input_list[0])
    col_index = int(input_list[1])
    clut_index = int(input_list[2])

    bitmap[row_index][col_index] = clut_index

    colorpixel(row_index, col_index, clut_index, square_length)
    index_input = input("Please input another row number, a column number, and a color number separated by spaces, then hit Enter. To finish coloring, hit Enter without entering any values: ")

#prints the bitmap array
print(bitmap)
    
done()

【参考方案1】：

我相信问题出在这里：

for row in range(rows):
    bitmap.append(rowline)

矩阵中的每一行都是相同的列表，我们需要让它们唯一列表：

for row in range(rows):
    bitmap.append(list(rowline))  # force a copy

这不是 Python 乌龟问题，而是通用 Python 编程问题。

【讨论】：

非常感谢！这解决了问题，我真的很感激。 :)