Question

我写了一个python脚本，根据速度和角度显示射弹的覆盖距离。

但是，它没有从用户那里读取另外一个函数（ask_values（））这两个变量。

是什么阻止了covered_distance（）函数读取用户在ask_values（）中输入的2个变量（theta和velocity）？

这是程序输出：

Projectile angle:   10
Velocity:       10
Angle: 10.0 Speed: 10.0
Angle: 0.0 Speed: 0.0 

Distance covered: 0.0

这是程序本身：

# IMPORT MODULES
from math import *          # Import all methods/attributes from math module
import sys                  # Import sys.exit()

# DECLARE VARIABLES
theta = 0.0                 # theta = angle at which the projectile is launched
velocity = 0.0              # velocity = speed of the projectile
percent_distance_var = 0.0  # percent_distance_var = percentage of the covered distance
max_distance_var = 0.0      # max_distance_var = maximum distance
covered_distance_var = 0.0  # covered_distance_var = covered distance

# Covered distance
def covered_distance(theta_, velocity_, covered_distance_var_):   # Arguments: (theta, speed, covered_distance_var)
    covered_distance_var_ = 0.2041*((velocity_)**2)*sin(theta_)*cos(theta_) # Calculate 0.2041*((velocity)**2)*sin(theta)*cos(theta)
    data = dict(angle=theta_, speed=velocity_, distance=covered_distance_var_)
    print("Angle: {angle} Speed: {speed} \n \nDistance covered_: {distance}".format(**data)) # Doesn't print out the correct variables
    return covered_distance_var_         # Return covered_distance_var

# Ask user for values
def ask_values(theta, velocity):
    theta = float(input("Projectile angle: \t"))
    velocity = float(input("Velocity: \t \t"))
    print("Angle: {} Speed: {}".format(theta, velocity)) # Prints out the correct variables
    return(theta, velocity)


def main():# Main method
    ask_values(theta, velocity) # Ask for values
    covered_distance(theta, velocity, covered_distance_var)

# EXECUTE CODE
if __name__ == "__main__":   # If "__main__" statement
    main()  # Main() method

Answer 1

您必须捕获函数在main中返回的值，否则它们将被丢弃并且永远不会进入命名空间。当您访问该名称时，它在本地找不到任何内容，并查看参数的全局值。所以不要这样：

def main():# Main method
    ask_values(theta, velocity) # Ask for values
    covered_distance(theta, velocity, covered_distance_var)

执行：

def main():# Main method
    theta, velocity = ask_values(theta, velocity) # Ask for values
    covered_distance(theta, velocity, covered_distance_var)

否则theta和velocity值将与您在此处定义的值相对应：

# DECLARE VARIABLES
theta = 0.0                 # theta = angle at which the projectile is launched
velocity = 0.0              # velocity = speed of the projectile

在全局命名空间中。如果你想要用户输入，那么为这些变量赋值是没用的。 Python不是具有变量声明概念的静态类型语言。当变量被分配时，变量“就会存在”。

此外，您可能希望print获得最终结果：

print(covered_distance(theta, velocity, covered_distance_var))

功能无法识别全局变量

1 个答案: