This gist contains functions which recursively find all subsets of a set. The min and max subset size can be specified.

findAllSubsets.py

import numpy as np 

#This function retrieves all subsets in a set recursively.
def findSubsets(allSubsets,subset,currentIndex,maxSubsetSize):      
    if(len(subset) == currentIndex):
        return allSubsets
    
    newSet = []
    for i in range(0,len(allSubsets)):
      if(len(allSubsets[i]) < maxSubsetSize):
        newSet = allSubsets[i].copy()
        newSet.append(subset[currentIndex])
        allSubsets.append(newSet)
        
    findSubsets(allSubsets, subset, currentIndex+1,maxSubsetSize)
    
 # Find all subsets of a specific size
def findAllSubsetsSpecificSize(array, subsetSize,maxSubsetSize):
    allSubsets = [[]]
    findSubsets(allSubsets,array,0,maxSubsetSize)
    returnSet = []
    for sets in allSubsets:
        if(len(sets) == subsetSize):
            returnSet.append(sets)      
    return returnSet

#Find all subsets larger than minSubsetSize
def findAllSubsetsWithinRange(array, minSubsetSize,maxSubsetSize):
    allSubsets = [[]]
    findSubsets(allSubsets,array,0,maxSubsetSize)
    returnSet = []
    for sets in allSubsets:
        if(len(sets) >= minSubsetSize):
            returnSet.append(sets)      
    return returnSet

#Example 
allSubsets = [[]]
indexOfSet = []
for i in range(0,28):
  indexOfSet.append(i)

minSizeSubset = 3 
maxSubsetSize = 7
allSubsets = findAllSubsetsWithinRange(indexOfSet,minSizeSubset,maxSubsetSize)
allSubsetsNumpy = np.array(allSubsets)
print(allSubsetsNumpy)