From a list, count how many numbers are within the standard deviation from the mean. (Python)

heights = [180, 172, 178, 185, 190, 195, 192, 200, 210, 190]

height_sum = sum(heights)

mean = height_sum / len(heights)

# **2 makes negatives (heights less than the mean) become positive.

diff_list = [(x - mean) ** 2 for x in heights]

variance = sum(diff_list) / len(heights)

# We get the square root in order to get back the original units.

standard_deviation = variance **0.5

# Now we just need to find out how many heights are within the

# standard deviation from the mean.

count = 0

upper_lim = mean + standard_deviation

lower_lim = mean - standard_deviation

# Count how many heights are within the

# standard deviation from the mean.

for height in heights:

    if lower_lim < height < upper_lim:

        count += 1

       

print(count)

''' Or as a class, initiated with the heights list: '''

class Std():

   

    def __init__(self, data: list):

        self.data = data

        self.mean = self._get_mean()

        self.var = self._get_variance()

        self.std = self._get_std_from_var()

       

        self.upper_lim = self.mean + self.std

        self.lower_lim = self.mean - self.std

   

        self.in_range = lambda x: self.lower_lim < x < self.upper_lim

        self.count_within = len(list(filter(self.in_range, self.data)))

    def _get_mean(self):

        return sum(self.data) / len(self.data)

    def _get_variance(self):

        diff_list = [(x - self.mean) ** 2 for x in self.data]

        return sum(diff_list) / len(diff_list)

    def _get_std_from_var(self):

        return self.var **0.5

std = Std(heights)

print(std.count_within)