/
stats.py
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/
stats.py
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from collections import Counter
from helpers.linear_algebra import sum_of_squares, dot
import math
num_friends = [100, 49, 41, 40, 25, 21, 21, 19, 19, 18, 18, 16, 15, 15, 15, 15, 14, 14, 13, 13, 13, 13, 12, 12, 11, 10,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1]
def make_friend_counts_histogram(plt):
friend_counts = Counter(num_friends)
xs = range(101)
ys = [friend_counts[x] for x in xs]
plt.bar(xs, ys)
plt.axis([0, 101, 0, 25])
plt.title("Histogram of Friend Counts")
plt.xlabel("# of friends")
plt.ylabel("# of people")
plt.show()
num_points = len(num_friends) # 204
largest_value = max(num_friends) # 100
smallest_value = min(num_friends) # 1
sorted_values = sorted(num_friends)
# smallest_value = sorted_values[0] # 1
second_smallest_value = sorted_values[1] # 1
second_largest_value = sorted_values[-2] # 49
# this isn't right if you don't from __future__ import division
def mean(x):
return sum(x) / len(x)
def median(v):
"""finds the 'middle-most' value of v"""
n = len(v)
sorted_v = sorted(v)
midpoint = n // 2
if n % 2 == 1:
# if odd, return the middle value
return sorted_v[midpoint]
else:
# if even, return the average of the middle values
lo = midpoint - 1
hi = midpoint
return (sorted_v[lo] + sorted_v[hi]) / 2
def quantile(x, p):
"""returns the pth-percentile value in x"""
p_index = int(p * len(x))
return sorted(x)[p_index]
def mode(x):
"""returns a list, might be more than one mode"""
counts = Counter(x)
max_count = max(counts.values())
return [x_i for x_i, count in counts.items()
if count == max_count]
# "range" already means something in Python, so we'll use a different name
def data_range(x):
return max(x) - min(x)
def de_mean(x):
"""translate x by subtracting its mean (so the result has mean 0)"""
x_bar = mean(x)
return [x_i - x_bar for x_i in x]
def variance(x):
"""assumes x has at least two elements"""
n = len(x)
deviations = de_mean(x)
return sum_of_squares(deviations) / (n - 1)
def standard_deviation(x):
return math.sqrt(variance(x))
def interquartile_range(x):
return quantile(x, 0.75) - quantile(x, 0.25)
####
#
# CORRELATION
#
#####
daily_minutes = [1, 68.77, 51.25, 52.08, 38.36, 44.54, 57.13, 51.4, 41.42, 31.22, 34.76, 54.01, 38.79, 47.59, 49.1,
27.66, 41.03, 36.73, 48.65, 28.12, 46.62, 35.57, 32.98, 35, 26.07, 23.77, 39.73, 40.57, 31.65, 31.21,
36.32, 20.45, 21.93, 26.02, 27.34, 23.49, 46.94, 30.5, 33.8, 24.23, 21.4, 27.94, 32.24, 40.57, 25.07,
19.42, 22.39, 18.42, 46.96, 23.72, 26.41, 26.97, 36.76, 40.32, 35.02, 29.47, 30.2, 31, 38.11, 38.18,
36.31, 21.03, 30.86, 36.07, 28.66, 29.08, 37.28, 15.28, 24.17, 22.31, 30.17, 25.53, 19.85, 35.37, 44.6,
17.23, 13.47, 26.33, 35.02, 32.09, 24.81, 19.33, 28.77, 24.26, 31.98, 25.73, 24.86, 16.28, 34.51,
15.23, 39.72, 40.8, 26.06, 35.76, 34.76, 16.13, 44.04, 18.03, 19.65, 32.62, 35.59, 39.43, 14.18, 35.24,
40.13, 41.82, 35.45, 36.07, 43.67, 24.61, 20.9, 21.9, 18.79, 27.61, 27.21, 26.61, 29.77, 20.59, 27.53,
13.82, 33.2, 25, 33.1, 36.65, 18.63, 14.87, 22.2, 36.81, 25.53, 24.62, 26.25, 18.21, 28.08, 19.42,
29.79, 32.8, 35.99, 28.32, 27.79, 35.88, 29.06, 36.28, 14.1, 36.63, 37.49, 26.9, 18.58, 38.48, 24.48,
18.95, 33.55, 14.24, 29.04, 32.51, 25.63, 22.22, 19, 32.73, 15.16, 13.9, 27.2, 32.01, 29.27, 33, 13.74,
20.42, 27.32, 18.23, 35.35, 28.48, 9.08, 24.62, 20.12, 35.26, 19.92, 31.02, 16.49, 12.16, 30.7, 31.22,
34.65, 13.13, 27.51, 33.2, 31.57, 14.1, 33.42, 17.44, 10.12, 24.42, 9.82, 23.39, 30.93, 15.03, 21.67,
31.09, 33.29, 22.61, 26.89, 23.48, 8.38, 27.81, 32.35, 23.84]
def covariance(x, y):
n = len(x)
return dot(de_mean(x), de_mean(y)) / (n - 1)
def correlation(x, y):
stdev_x = standard_deviation(x)
stdev_y = standard_deviation(y)
if stdev_x > 0 and stdev_y > 0:
return covariance(x, y) / stdev_x / stdev_y
else:
return 0 # if no variation, correlation is zero
outlier = num_friends.index(100) # index of outlier
num_friends_good = [x
for i, x in enumerate(num_friends)
if i != outlier]
daily_minutes_good = [x
for i, x in enumerate(daily_minutes)
if i != outlier]
# alpha, beta = least_squares_fit(num_friends_good, daily_minutes_good)
if __name__ == "__main__":
print("num_points", len(num_friends))
print("largest value", max(num_friends))
print("smallest value", min(num_friends))
print("second_smallest_value", sorted_values[1])
print("second_largest_value", sorted_values[-2])
print("mean(num_friends)", mean(num_friends))
print("median(num_friends)", median(num_friends))
print("quantile(num_friends, 0.10)", quantile(num_friends, 0.10))
print("quantile(num_friends, 0.25)", quantile(num_friends, 0.25))
print("quantile(num_friends, 0.75)", quantile(num_friends, 0.75))
print("quantile(num_friends, 0.90)", quantile(num_friends, 0.90))
print("mode(num_friends)", mode(num_friends))
print("data_range(num_friends)", data_range(num_friends))
print("variance(num_friends)", variance(num_friends))
print("standard_deviation(num_friends)", standard_deviation(num_friends))
print("interquartile_range(num_friends)", interquartile_range(num_friends))
print("covariance(num_friends, daily_minutes)", covariance(num_friends, daily_minutes))
print("correlation(num_friends, daily_minutes)", correlation(num_friends, daily_minutes))
print("correlation(num_friends_good, daily_minutes_good)", correlation(num_friends_good, daily_minutes_good))
# print("R-squared value", r_squared(alpha, beta, num_friends_good, daily_minutes_good))