# How Epidemics Spread 1, Exercise 3: a point-source outbreak
# 80 guests share one dinner (assumed). Each falls ill with probability 0.4
# (assumed attack rate). The time from the meal to onset is 6 hours plus 21 hours
# times the sum of two random numbers (a bell-ish shape between 6 and 48 hours;
# assumed). Use random.Random(7). Count onsets in 6-hour bins
# after the meal and draw the curve; then say whether the shape looks like a
# point-source or a propagated outbreak, and why.
import random

rng = random.Random(7)
guests, attack_rate = 80, 0.4
onsets = []
for _ in range(guests):
    if rng.random() < attack_rate:
        onsets.append(6 + 21 * (rng.random() + rng.random()))

print("cases:", len(onsets), f"({len(onsets) / guests:.0%} of guests)")
print(f"first onset {min(onsets):.1f} h, last onset {max(onsets):.1f} h")
for lo in range(0, 48, 6):
    n = sum(1 for t in onsets if lo <= t < lo + 6)
    print(f"{lo:2d}-{lo + 6:2d} h {n:2d} " + "#" * n)

# Output when run:
# cases: 39 (49% of guests)
# first onset 11.3 h, last onset 41.3 h
#  0- 6 h  0 
#  6-12 h  3 ###
# 12-18 h  9 #########
# 18-24 h  8 ########
# 24-30 h 13 #############
# 30-36 h  2 ##
# 36-42 h  4 ####
# 42-48 h  0