Allocating array (list) algorithm permutations in python
So i'm having trouble to solve the following problem:
given an array size, lets say for the ease of the question size =20
it is filled with zeros as follows arr = [0]*20 ==> [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
we have couple of constant sample sizes, such as 4,3,2
SampleA=4, SampleB=3, SampleC= 2
i need to have the permutations/variations of how to allocate the list.
i can put each sample in different place/index
for example, sampleA= 4 i can put it in indexes of 0:3, or 1:4... 15:19.. (as you can see, there are quite a lot of possibilities)
the thing gets complicated once it get more crowded, for example:
3+2+3 +4
[0, x, x, x, 0, 0, x x, 0, x, x, x, 0, 0, 0, 0, x, x,x, x]
what i basically need, is to find all the possibilities to allocate samples,
i get a dictionary: key = sample size of indexes, and the value=many times it repeats.
for the upper example: {3:2,2:1,4:1}
and i would like the function to return a list of indexes !=0
for this example: [0, x, x, x, 0, 0, x x, 0, x, x, x, 0, 0, 0, 0, x, x,x, x]
the function will return: list_ind = [0,5,6,9,13,14,15,16]
1 answer

so i asked a colleague to help, and we came into a solution:
i put an example of: 4:2, 3:1, 2:1
or verbally:
two times 4, one time 3, one time 2 the code below:
*if someone can optimize, will be great
size_of_wagon = 20 dct = {4:2,3:1,2:1} l = [item for sublist in [[k] * v for (k, v) in dct.items()] for item in sublist] def gen_func(lstOfSamples, length, shift): try: # print(f'lstOfSamples={lstOfSamples}') sample = lstOfSamples[0] # Take first sample for i in range(length  sample): for x in gen_func(lstOfSamples[1:], length  (sample + i), shift + sample + i): yield [(shift + i, sample)] + x except: yield [] g = list(gen_func(l, size_of_wagon, 0)) for i in g: print(i) print(len(g))