TASK: Calculate the ratios of integers in an array that are positive, negative, and zero. Print the decimal value of each fraction on a new line with six places after the decimal.

Python:

def plusMinus(arr):
  size = len(arr)
  plus = [i for i in arr if i > 0]
  minus = [i for i in arr if i < 0]
  zero = [i for i in arr if i is 0]
  print('{:.6g}'.format(len(plus) / size))
  print('{:.6g}'.format(len(minus) / size))
  print('{:.6g}'.format(len(zero) / size))

if __name__ == '__main__':
    arr = [-4, 3, -9, 0, 4, 1]
    plusMinus(arr)

Result:

0.5
0.333333
0.166667

Better code from a better coder:

def plusMinus(arr):
  length = len(arr)
  zero = arr.count(0) / length
  positive = len([x for x in arr if x > 0]) / length
  negative = 1 - zero - positive

  print("{:.6f}\n{:.6f}\n{:.6f}\n".format(positive, negative, zero))

Reference: Plus Minus (Hackerrank)