List Indices must be integer or slices, not float-CodePudding

So I was creating a median calculator, and I came upon this error (the heading)

    def median(x):
      #finds the median of a column
      if len(x) % 2 == 0:
        y = len(x) / 2
        medknot = x[y]   x[y][-1]
        med = medknot / 2
        return med
      elif len(x) % 2 == 1:
        y = len(x)//2
        med = x[y]
        return med

    l1 = [5, 6, 7, 8, 9, 6, 5, 5]
    print(median(l1))

What is the error in my code?

CodePudding user response：

/ always returns a float, even if the result could be an integer.

>>> 1/1
1.0

Use:

y = len(x) // 2

Also, the next line doesn't make sense:

medknot = x[y]   x[y][-1]

As the output of x[y] should be a scalar. You probably want medknot = x[y] x[y-1]

Finally, the input list should be sorted to compute a correct median.

You can also simplify the code:

def median(x):
    # sort x
    x = sorted(x)

    y = len(x) // 2 
    med = x[y]
    if len(x) % 2 == 0:
        med = (med   x[y-1])/2
    return med

print(median([1, 2, 3]))
# 2

print(median([1, 2, 3, 4]))
# 2.5

print(median([4, 1, 2, 3]))
# 2.5

CodePudding user response：

If you are working on the latest Python version 3.8 , you could try this standard statistics lib. It could also speed up in case you're dealing with a huge list of numbers.


from statistics import median

lst = [5, 6, 7, 8, 9, 6, 5, 5]
median_val = median(lst)       # 6.0