How would you call this operation? how would you e...
# present-companym
Mariano Guerra
10/12/2021, 12:55 PM
How would you call this operation? how would you express it abstractly and if you know, how would you express it in a language that can do it? (I know the general operation is called transpose, but here I'm transposing a subset)
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George
10/12/2021, 1:15 PMisn’t that called a “pivot table”
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George
10/12/2021, 1:20 PMthere usual isn’t reverse operation because the amounts can be aggregated. example if you had two rows
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Mariano Guerra
10/12/2021, 1:23 PM
In pandas and R they are pivot and melt, in SQL they seem to be pivot and unpivot
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Andrew F
10/12/2021, 3:11 PMThis seems to rely on redundancy in the second source column for its well-definedness, or at least its meaningfulness. If I really wanted to be picky about it, I would project it entirely into (country, period, number) tuples and then try fitting it into another table shape.
Andrew F
10/12/2021, 3:50 PMReading further, it seems like the special case of a pivot that kinda looks like a transpose is one where you require that there be exactly one item in each "aggregated" field, and then don't actually aggregate. Is that right?
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Mariano Guerra
10/12/2021, 8:39 PM
@Andrew F yes, it a subset of pivot
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wtaysom
10/13/2021, 3:05 AMOver here we call it pivoting including the special case where you don't do any aggregation. There are many ways to pivot. Swapping rows and columns is transposing. Removing a field means that you're going to marginalize or aggregate over it.