import scipy.stats as stats
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

# values for x (all between 0 and 30): 
x = np.linspace(0, 30, num=31)

# PMF for all these values:
fx_3 = stats.poisson.pmf(x, 3) 
fx_5 = stats.poisson.pmf(x, 5) 
fx_10 = stats.poisson.pmf(x, 10) 
fx_15 = stats.poisson.pmf(x, 15) 

# collect values in DataFrame:
result_3 = pd.DataFrame({'x': x, 'fx_3': fx_3}) 
result_5 = pd.DataFrame({'x': x, 'fx_5': fx_5}) 
result_10 = pd.DataFrame({'x': x, 'fx_10': fx_10}) 
result_15 = pd.DataFrame({'x': x, 'fx_15': fx_15}) 
#print(f'result_3: \n{result_3}\n')
#print(f'result_5: \n{result_5}\n')
#print(f'result_10: \n{result_10}\n')
#print(f'result_15: \n{result_15}\n')

"""
# plot:
plt.bar(x, fx_3, color='0.6', width = 0.1)
plt.xlabel('x')
plt.ylabel('P(X=x)')
plt.show()

plt.bar(x, fx_5, color='0.6', width = 0.1)
plt.xlabel('x')
plt.ylabel('P(X=x)')
plt.show()

plt.bar(x, fx_10, color='0.6', width = 0.1)
plt.xlabel('x')
plt.ylabel('P(X=x)')
plt.show()

plt.bar(x, fx_15, color='0.6', width = 0.1)
plt.xlabel('x')
plt.ylabel('P(X=x)')
plt.show()
"""
# create graph:
fig = plt.figure(figsize=(14,7)) 

plt.subplot(221).set(title='Probability of Poisson with lambda=3')
_ = plt.bar(x, fx_3, color='0.6', width = 0.1)
#_ = plt.stem(x, fx_3, use_line_collection = True)
_ = plt.xlabel('x')
_ = plt.ylabel('P(X=x)')

plt.subplot(222).set(title='Probability of Poisson with lambda=5')
_ = plt.bar(x, fx_5, color='0.6', width = 0.1)
#_ = plt.stem(x, fx_5, use_line_collection = True)
_ = plt.xlabel('x')
_ = plt.ylabel('P(X=x)')

plt.subplot(223).set(title='Probability of Poisson with lambda-10')
_ = plt.bar(x, fx_10, color='0.6', width = 0.1)
#_ = plt.stem(x, fx_10, use_line_collection = True)
_ = plt.xlabel('x')
_ = plt.ylabel('P(X=x)')

plt.subplot(224).set(title='Probability of Poisson with lambda=15')
_ = plt.bar(x, fx_15, color='0.6', width = 0.1)
#_ = plt.stem(x, fx_15, use_line_collection = True)
_ = plt.xlabel('x')
_ = plt.ylabel('P(X=x)')

fig.subplots_adjust(hspace=0.4, wspace=0.2) # 하측그림의 상하 및 우측그림의 좌우 간격을 조정
plt.show()
#plt.savefig('D:/BOOK/PyBasics/PyStat/code/b1-ch4-6.png')