is it possible to have a variable amount of elifs in an if/elif/else chain?

Question

I am playing around with Markov-Chains and depending on the number of states I need the same amount of ifs.

So if I happen to have a chain with 4 (from 0 to 3) states, my logic is as follows:

startingstate = <is a variable>

if state == 0:
    change = <some code that tells me what the state has changed to if it has>
    if change == 0:
        <do somethin01>
    elif change == 1:
        <do something1>
    elif change == 2:
        <do something2>
    elif change == 3:
        <do something3>
elif state == 1:
    <same stuff as above>
    
    and so on until we get to the last else of state == 3

Usually when I had such problems that required weird loop fiddling, there was some easier logic to get it done, but I cannot wrap my head around this. Do I have to go with a variable amount of elifs? If yes how do I do it? Or is there a better way?

Thanks!:)

My current attempt looks like this:

b = 3 #amount of possible states
prob = 1 
s= 0 #helper variable
init_state = 0 
state_list = []
forecast = 6
f = 0 

while f != forecast:
    while s < b:
        o=0 #helper variable
        if init_state == s:
            change = np.random.choice(transitionName[s],replace=True,p=transitionMatrix[s])
            print(change)
            while o < b:
                if change == transitionName[s][o]:
                    prob = prob * transitionMatrix[s][o]
                    init_state = o
                    print(prob)
                    state_list.append(s)
                o+=1
        s+=1
    f+=1

with:

transitionName
Out[83]: 
[['0 to 0', '0 to 1', '0 to 2'],
 ['1 to 0', '1 to 1', '1 to 2'],
 ['2 to 0', '2 to 1', '2 to 2']]

transitionMatrix
Out[84]: 
[[0.8333333333333334, 0.1111111111111111, 0.05555555555555555],
 [1.0, 0.0, 0.0],
 [0.3333333333333333, 0.0, 0.6666666666666666]]

this code is supposed to fill the state_list with 6 states, as forecast = 6. Somewhere something is wonky though and it only works if the state following the current state is different than the current state. How do I have to rearrange the loops so that I will always get forecast amount of items in state_list ?

Maybe you should make a list or dict of functions `things = [somethin01, somethin02]`, etc. Then you can call the correct one based on `change`: `things[change]()` — Mark, Jan 16 '22 at 02:27

score 1 · Answer 1 · answered Jan 16 '22 at 11:30

1

Building upon @Mark's comment, you may make a dict whose keys are (state, change) tuples and whose values are the functions you will call:

things = {(0,0) : something00, (0,1) : something01, ..., (3,3) : something33}
change = <code to find the change>
things[(state, change)]() ##calls one of the <somethingXX> functions

answered Jan 16 '22 at 11:30

gimix

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thanks, i'll try that next. I have edited my question with my current attempt and I am a bit closer to the solution. Right now it only works when the state following the current state is different than the current state. – Stefan 44 Jan 16 '22 at 12:14

is it possible to have a variable amount of elifs in an if/elif/else chain?

1 Answers1