Question

Using Python3,

I have this list called L1 which contains the following:

L1 = [4420, 4421, 4422, 4423, 4424, 4425, 4427, 4435, 5135, 5136, 5137, 5139, 5149, 6216, 6217, 6218, 6219, 6221, 6232, 7458, 7459, 7460, 7461, 7462, 7464, 7473]

However, I need to filter this list by intervals of 8 and record the first instance where it is inside this interval, and the filtered outputs are then put into a separate list called L2. To clarify what I mean, this interval of 8 originates from 0 and continues increasing by 8 so we will have (0,8,16,24,...,4416,4424,...), so the items I want in my filtered list should be:

L2 = [4420, 4424, 4435, 5135, 5136, 5149, 6216, 6232, 7458, 7464, 7473]

So basically every time an item % 8 == 0 or is the first instance within the interval of 8, the item is appended to L2.

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To clarify how I need to filter the items in this original list L1, for every interval of 8 (so it will generate intervals like this: 0,8,16,24,32,..,4416,4424,4432,4440,...,5128,5136,5144,...), every time a number inside L1 is the first occurrence inside a given interval, that particular number is appended to L2 and any other numbers inside that same interval are ignored.

Answer 1

'''

Python version : 3.6

Python program to filter the given list by intervals of 8 and record the first instance where it is inside this interval

'''

# given list

L1 = [4420, 4421, 4422, 4423, 4424, 4425, 4427, 4435, 5135, 5136, 5137, 5139, 5149, 6216, 6217, 6218, 6219, 6221, 6232, 7458, 7459, 7460, 7461, 7462, 7464, 7473]

# get the minimum element of L1

minItem = min(L1)

# get the maximum element of L1

maxItem = max(L1)

# get the start element for the range of interval of 8

minItem = (minItem-(minItem%8))

# get the last element for the range of interval of 8

maxItem = (maxItem + ((8-(maxItem%8))))

length = int((maxItem - minItem)/8) # get the total number of intervals

# create the list that contains if the element of a particulare interval is included in L2 or not

# initialize all the elements of this list to False

itemExist = [False]*length

L2 = []

# loop over the elements of L1

for item in L1:

               count = 0

               # get the interval range of this item

               for i in range(minItem,maxItem,8):

                              if item >=i and item <=i+7:

                                             if not itemExist[count]: # check if the item for this interval has been included or not

                                                            # if not included, include this item in L2 and reflect the same in the list itemList

                                                            itemExist[count] = True

                                                            L2.append(item)

                                             else:

                                                            break

                              else:

                                             count = count + 1

# print the resulting L2 list

print(L2)                                            

#end of program

Code Screenshot:

Python version 3.6 Python program to filter the given 1ist by intervals of 8 and record the first instance where it is inside this interval given list L1 [4420, 4421, 4422, 4423, 4424, 4425, 4427, 4435, 5135, 5136, 5137, 5139, 5149, 6216, 6217, 6218, 6219, 6221, 6232, 7458, 7459, 7460, 7461, 7462, 7464, 7473 element of L1 minItem = min (L1) get the maximum element of L1 maxItem max (L1) range of interval of 8 minltem (minItem-(minItemk8)) get the last element for the range of interval of maxItem (maxItem ((8-(maxItem%8) )) length int ((maxItem minItem)/8) get the total number of intervals tcreate Ethe list that contains if the element of a particulare interval is included in 2 or not ntS of thiS list to False ze

23 L2= 24 25 # loop over the elements of L1 Efor item in L1 26 count 0 get the interval range of this item for i in range (minItem , maxI tem, 8) 27 28 29 if item >i and item <=i+7: 30 if not itemExist [count]: # check if the item for this interval has been included or not 31 if not included, include this item in L2 and reflect the same in the list itemList itemExist [count]= True L2.append (item) 32 33 34 35 else 36 break 37 else: = Count + 1 38 count 39 print the resulting L2 list print (L2) 40 41 42 #end of program 43

Output:

[4420, 4424, 4435, 5135, 5136, 5149, 6216, 6232, 7458, 7464, 7473]