Calculate the standard deviation of the following dataΒΆ

Calculate the standard deviation of the following data.
Expected output:
Sample Data:
[4, 2, 5, 8, 6]
Standard Deviation:
2.23606797749979
import math
import sys

def sd_calc(data):

    n = len(data)

    if n <= 1:
        return 0.0

    mean, sd = avg_calc(data), 0.0

    # calculate stand. dev.
    for el in data:
        sd += (float(el) - mean)**2
    sd = math.sqrt(sd / float(n - 1))

    return sd

def avg_calc(ls):

    n, mean = len(ls), 0.0

    if n <= 1:
        return ls[0]

    # calculate average
    for el in ls:
        mean = mean + float(el)
    mean = mean / float(n)

    return mean

# test
data = [4, 2, 5, 8, 6]
print("Sample Data: ", data)
print("Standard Deviation : ", sd_calc(data))

Output:

Sample Data:  [4, 2, 5, 8, 6]
Standard Deviation :  2.23606797749979