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Python – Extract elements with Range consecutive occurrences
  • Last Updated : 31 Dec, 2019

Sometimes while working with data, we can have a problem in which we need to select some of the elements that occur range times consecutively. This problem can occur in many domains. Let’s discuss certain ways in which this problem can be solved.

Method #1 : Using groupby() + list comprehension
This task can be performed using above functionalities. In this, we group all the numbers that are occurring range consecutively. We iterate the list using list comprehension.




# Python3 code to demonstrate working of
# Extract elements with Range consecutive occurrences
# using groupby() + list comprehension
from itertools import groupby
  
# initialize list 
test_list = [1, 1, 4, 5, 5, 6, 7, 7, 7, 8, 8, 8, 8]
  
# printing original list 
print("The original list : " + str(test_list))
  
# initialize strt, end 
strt, end = 2, 3
  
# Extract elements with Range consecutive occurrences
# using groupby() + list comprehension
res1 = [i for i, j in groupby(test_list) if len(list(j)) <= end]
res2 = [i for i, j in groupby(test_list) if len(list(j)) >= strt]
res = list(set(res1) & set(res2))
  
# printing result
print("The range consecutive elements are : " + str(res))
Output :
The original list : [1, 1, 4, 5, 5, 6, 7, 7, 7, 8, 8, 8, 8]
The range consecutive elements are : [1, 5, 7]

 

Method #2 : Using list comprehension + slice() + groupby()
This task can also be performed using above functions. In this, we just perform grouping in similar way as above but the way we extract consecutive elements is by slice().






# Python3 code to demonstrate working of
# Extract elements with Range consecutive occurrences
# using groupby() + list comprehension + islice()
from itertools import groupby, islice
  
# initialize list 
test_list = [1, 1, 4, 5, 5, 6, 7, 7, 7, 8, 8, 8]
  
# printing original list 
print("The original list : " + str(test_list))
  
# initialize strt, end 
strt, end = 2, 3
  
# Extract elements with Range consecutive occurrences
# using groupby() + list comprehension + islice()
res1 = [i for i, j in groupby(test_list) if len(list(islice(j, 0, strt))) >= strt]
res2 = [i for i, j in groupby(test_list) if len(list(islice(j, 0, end))) <= end]
res = list(set(res1) & set(res2))
  
# printing result
print("The range consecutive elements are : " + str(res))
Output :
The original list : [1, 1, 4, 5, 5, 6, 7, 7, 7, 8, 8, 8]
The range consecutive elements are : [1, 5, 7, 8]

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