Condition in list - Python

Question

I am working in python and I have this list

for i in range(0, len(state1)):
    observations = [{'state_transitions': [{'state': state1[i],
                                            'action': action[i], 
                                            'state_': state2[i]},],
                     'reward': 0},]

I would like to put the for clause inside the observations, something like this (but this is giving me an error):

observations = [
    for i in range(0, len(state1)):
        {'state_transitions': [{'state': state1[i],
                                'action': action[i],
                                'state_':state2[i]},],
        'reward': 0},]
print observations;

Can anyone help me with this?

Answer 1

What you are trying to accomplish (creating a list based on the results from a for loop) is called a list comprehension. Syntax is as follows: my_list = [do_something(item) for item in my_iterable].

Which gives:

observations = [
   { 
      'state_transitions': [
          { 'state': state1[i], 'action': action[i], 'state_':state2[i] },
       ],
        'reward': 0
    } for i in range(0, len(state1))
]
print(observations)