Question

这是我正在为我的大学项目中的机器人编写的代码。这段代码有效，但是循环会不断地每秒打印一次语句，我希望它只在我改变输入条件时打印（打破if条件），所以它不会继续打印。有没有什么办法解决这一问题？我在这里先向您的帮助表示感谢。

PS：这是在python 2.7（我认为）

try:
    while True:
        #some stuff 
        if 0.01 < joystick.get_axis(1) <= 0.25:
            print ('moving backward with 25% speed')
            # performing some actions


        elif 0.25 < joystick.get_axis(1) <= 0.5:
            print ('moving forward with 50% speed')
            # performing some actions

        elif 0.5 < joystick.get_axis(1) <= 0.75:
            print ('moving backward with 75% speed')
            # performing some actions

while循环以相同的方式继续......

Answer 1

跟踪最后一个类别 - 类似的东西。

previous_category = 0
 while True:
        #some stuff 
    if 0.01 < joystick.get_axis(1) <= 0.25:
        if previous_category != 1:
           print ('moving backward with 25% speed')
        previous_category = 1
        # performing some actions

    elif 0.25 < joystick.get_axis(1) <= 0.5:
        if previous_category != 2:
           print ('moving forward with 50% speed')
        previous_category = 2
        # performing some actions

    elif 0.5 < joystick.get_axis(1) <= 0.75:
        if previous_category != 3:
           print ('moving backward with 75% speed')
        previous_category = 3
        # performing some actions

如果您因为重新格式化代码而感到失望，我认为这是一种更好的方法：

 previous_category = 0
 while True:
    val = joystick.get_axis(1)

    if 0.01 < val <= 0.25:
    category = 1
    #add 2 elif for the other categories, 2 and 3 

    if category == 1:
        # performing some actions
    elif category == 2:
        # performing some actions

    elif category == 3:
        # performing some actions

    #now that we've moved the object, we check if we need to print or not
    if category != previous_category:
       print_statement(category)
    #and we update previous_category for the next round, which will just be the current category
    previous_category = category

def print_statement(category):
   #handle printing here based on type, this is more flexible

Answer 2

您可以使用存储最后打印值的全局整数来完成此操作。像这样：

_last_count = None
def condprint(count):
    global _last_count
    if count != _last_count:
        print('Waiting for joystick '+str(count))
        _last_count = count

如何打印一次，直到if条件被打破？

2 个答案: