Question

import turtle
index = 0 #to traverse through list
turtle.setup(800,600) # Change the width of the drawing to 800px and the 
height to 600px.
wn = turtle.Screen()
sammy = turtle.Turtle()

inFile = open('mystery.txt','r')
outFile=inFile.read()
outFileContent = outFile.split ()
while index != (len(outFileContent)): #for item in the list
    if str(outFileContent [index]) == "UP": #if the current index goes up, pen up
        sammy.penup()

    elif str(outFileContent [index]) == "DOWN": #else if its down, pen down
        sammy.pendown ()

    elif outFileContent[index].isalpha () == False : #if its a number, go to 
those coordinates
        sammy.goto (int(outFileContent[index]),int(outFileContent[index+1])) #convert from str to int

    index+=1 #goes to next value in list


    print ((int(outFileContent [index]), int(outFileContent[index+1]))) #make sure its printing the right coordinates

inFile.close()
wn.mainloop ()

所以这个程序应该打开一个列表，然后让乌龟在列表上执行命令。如果该行读取UP，则乌龟将笔放上。如果该行显示为DOWN，则乌龟将笔放下。如果该行是一对数字，则乌龟将转到那些坐标。以下是文件＆＃34; mystery.txt＆＃34;的内容：

UP
-218 185
DOWN

但是，当我运行程序时，它会输出：

Traceback (most recent call last):
File "C:\Users\Yariel\Google 
Drive\Coding\Python\Scripts\Files\turtle_file_mystery_shape.py", line 23, in <module>
print ((int(outFileContent [index]), int(outFileContent[index+1]))) #make 
sure its printing the right coordinates
ValueError: invalid literal for int() with base 10: 'DOWN'

我不知道它为什么会变成一个我从未指定过的整数。（如果查看print语句中的坐标，则输出正确的坐标）。那有什么帮助吗？关于如何解决这个问题？

Answer 1

我强烈建议学习如何使用ipdb。简单地说，只需将行import ipdb; ipdb.set_trace()放在打印语句之前，然后单步执行n，然后继续执行c。

     22     import ipdb; ipdb.set_trace()
---> 23     print ((int(outFileContent [index]), int(outFileContent[index+1]))) #make sure its printing the right coordinates
     24 

ipdb> outFileContent
['UP', '-218', '185', 'DOWN']
ipdb> outFileContent[index]
'-218'
ipdb> outFileContent[index+1]
'185'
ipdb> c
(-218, 185)

     21 
---> 22     import ipdb; ipdb.set_trace()
     23     print ((int(outFileContent [index]), int(outFileContent[index+1]))) #make sure its printing the right coordinates

ipdb> outFileContent[index]
'185'
ipdb> outFileContent[index+1]
'DOWN'

很明显，在将索引增加1之后，您的错误来自while循环的第二个循环。我假设你想把索引增加三个？

请注意，您可能需要pip install ipdb --user。

Answer 2

坐标是一种特殊的输入案例。您需要将index增加1以容纳第二个int。

# ...
elif outFileContent[index].isalpha () == False : #if its a number, go to those coordinates
    sammy.goto (int(outFileContent[index]),int(outFileContent[index+1])) #convert from str to int
    # move print to here; indexing changed
    print ((int(outFileContent [index]), int(outFileContent[index+1])))
    # additional increment to index to accommodate second int
    index += 1

index+=1 #goes to next value in list
# ...

Answer 3

我建议您重新考虑一下，而不是修补您的代码。下面的返工将逐行处理神秘文件，而不是一次性处理，并且希望您更容易扩充和调试：

import sys
from turtle import Turtle, Screen

screen = Screen()
# Set width of the drawing to 800px and height to 600px
screen.setup(800, 600)

sammy = Turtle()

commands = {'UP': sammy.penup, 'DOWN': sammy.pendown}

with open('mystery.txt') as inFile:

    for line in inFile:
        content = line.rstrip().split()

        if len(content) == 1 and content[0] in commands:

            commands[content[0]]()  # eg. UP and DOWN

        elif len(content) == 2 and not content[0].isalpha() and not content[1].isalpha():

            # seem to be numbers, convert from str to int and go to those coordinates
            sammy.goto(int(content[0]), int(content[1]))

        else:
            print("Invalid input:", content, file=sys.stderr)

screen.mainloop()

Python无效的Int（）错误

3 个答案: