python “类型错误：‘builtin_function_or_method’ object 不可迭代”

Question

im trying to make a function that calculates the mad in a list but after i was done making it, it didnt work and said 'TypeError: 'builtin_function_or_method' object is not iterable' and i dont know why is said this. heres the code.

def mad(a):

    mean = sum(a)/len(a)

    absoluteDeviation = []
    for eachValue in input:
        absoluteDeviation.append(abs(eachValue - mean))
        eachValue += 1

    mad = sum(absoluteDeviation)/len(absoluteDeviation) 
    print(mad)
mad([2,4,6,8])

Answer 1

instead of

for eachValue in input:

It should be:

for eachValue in a:#since a is the iterable not input

there is no need for:

eachValue += 1

Code:

def mad(a):

    mean = sum(a)/len(a)

    absoluteDeviation = []
    for eachValue in a:
        absoluteDeviation.append(abs(eachValue - mean))
        #eachValue += 1

    return sum(absoluteDeviation)/len(absoluteDeviation) 
print(mad([2,4,6,8]))

Output:

$python3.10 iterable.py 
2.0

A better approach to calculate mean absolute deviation since we are using less memory as compare to above code:

"""
mean absolute deviation
"""
def mad(a):

    mean = sum(a)/float(len(a))

    mean_absolute_deviation = 0
    for eachValue in a:
        mean_absolute_deviation += abs(eachValue - mean)

    mean_absolute_deviation /= len(a)
    return mean_absolute_deviation

print(mad([2,4,6,8]))