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Thread: Formula for extracting certain elements from a list

  1. #1
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    Default Formula for extracting certain elements from a list

    I need a formula to iterate through list A and extract certain items and put into list B. I need to skip two items, extract the next three, skip two items, extract the next three, etc:

    Qt Code:
    1. A = (34, 35, 40, 41, 42, 22, 34, 43, 44, 45, 65, 78, 46, 47, 48)
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    I want:
    Qt Code:
    1. B = (40, 41, 42, 43, 44, 45, 46, 47, 48)
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    this is all I could get:
    Qt Code:
    1. for i, val in enumerate(A):
    2. B = (
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    thanks

  2. #2
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    Default Re: Formula for extracting certain elements from a list

    In pseudocode, assuming "i" is the index of the item in the list and i starts at 0:

    Qt Code:
    1. if i % 5 < 2, skip
    2. else extract
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    You should be able to do that in python. "%" is the "remainder" operator - it divides the left side by the right side and returns the remainder. If it isn't the same in python, I am sure there is a similar operator or function that does the same.
    <=== The Great Pumpkin says ===>
    Please use CODE tags when posting source code so it is more readable. Click "Go Advanced" and then the "#" icon to insert the tags. Paste your code between them.

  3. The following user says thank you to d_stranz for this useful post:

    dennisvz (20th July 2019)

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