For 循环不遍历整个列表

Question

I have the following code in Jupyter notebook that prints the radiuslist but only iterates the first result for the resultlist.

def areacirclelist(radiuslist):

    for oneradius in radiuslist:
        resultlist = []
        resultlist.append(math.pi*oneradius*oneradius)
        return resultlist

radiuslist = [1,2,4,8,21,80]

arealist = areacirclelist(radiuslist)
print ('For the circle with radii of ', radiuslist, 'the areas are', arealist)

I appreciate the help!

Answer 1

You shoul put resultlist = [] and the return statement outside the loop.

def areacirclelist(radiuslist):

    resultlist = []
    for oneradius in radiuslist:
        resultlist.append(math.pi*oneradius*oneradius)
    return resultlist

Answer 2

You need to define resultlist = [] outside the for loop. You're overwriting it every iteration.

EDIT: You also need to move the return statement outside the loop.

def areacirclelist(radiuslist):
    resultlist = []
    for oneradius in radiuslist:
        resultlist.append(math.pi * oneradius * oneradius)
    return resultlist


radiuslist = [1, 2, 4, 8, 21, 80]

arealist = areacirclelist(radiuslist)
print('For the circle with radii of ', radiuslist, 'the areas are', arealist)

Answer 3

resultlist only contains one number because it is initialized in the for-loop, so it will be set to [] every iteration.

You can simply fix it by moving the initialization outside the for-loop.

def areacirclelist(radiuslist):
    resultlist = [] # initialize HERE
    for oneradius in radiuslist:
        resultlist.append(math.pi * oneradius * oneradius)
    return resultlist

However, you can write it in a more simple and readable way:

def areacirclelist(radiuslist):
    return [math.pi * oneradius * oneradius for oneradius in radiuslist]