Building a Transition Matrix using words in Python/Numpy

Question

Im trying to build a 3x3 transition matrix with this data

days=[\'rain\', \'rain\', \'rain\', \'clouds\', \'rain\', \'sun\', \'clouds\', \'clouds\', 
  \'rai         


        

Answer 1

Below another alternative using pandas. Transitions list can be replaced with 'rain','clouds' etc.

import pandas as pd
transitions = ['A', 'B', 'B', 'C', 'B', 'A', 'D', 'D', 'A', 'B', 'A', 'D'] * 2
df = pd.DataFrame(columns = ['state', 'next_state'])
for i, val in enumerate(transitions[:-1]): # We don't care about last state
    df_stg = pd.DataFrame(index=[0])
    df_stg['state'], df_stg['next_state'] = transitions[i], transitions[i+1]
    df = pd.concat([df, df_stg], axis = 0)
cross_tab = pd.crosstab(df['state'], df['next_state'])
cross_tab.div(cross_tab.sum(axis=1), axis=0)