Clever Geek Handbook

Mapping variable dimensions

I have a data file that is sorted based on the first column

1 3 2
3 6
4 8 5 6 2
4 9
5 2 2

There is a key with three elements, for example seen = [4 8 5]

, which I want to find in the above array. Since some of the rows have less than three columns, the following code does not compare and I know that

take = [row for row in lines if row[0] == seen[0] and row[1] == seen[1] and row[2] == seen[2]]

So what should I do for rows with three columns?

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2 answers


By using a slice, you don't have to manually check all 3 elements and check the length:



take = [row for row in lines if row[:3] == seen]
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Add guard ( len(row) >= 3

):

take = [row for row in lines if len(row) >= 3 and row[0] == seen[0] and row[1] == seen[1] and row[2] == seen[2]]


This will short-circuit (and fail) the validation if the string does not have enough elements

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