Data algebra, going back to Codd's relational operators

What it does

When working with multiple data tables we often need to know how for a given set of keys, how many instances of rows each table has. I would like to use such an example in Python as yet another introduction to the data algebra (an alternative to direct Pandas or direct SQL notation). First let's…

I would like to use such an example in Python as yet another introduction to the data algebra (an alternative to direct Pandas or direct SQL notation). First let’s import our packages and set up our example data. from typing import List import pandas from data_algebra.data_ops import * import data_algebra.SQLite # some example data d1 = pandas . DataFrame ({ 'ID' : [ 2 , 3 , 7 , 7 ], 'OP' : [ 'A' , 'B' , 'B' , 'D' ], }) d2 = pandas . DataFrame ({ 'ID' : [ 1 , 1 , 2 , 3 , 4 , 2 , 4 , 4 , 5 , 5 , 6 ], 'OP' : [ 'A' , 'B' , 'A' , 'D' , 'C' , 'A' , 'D' , 'B' , 'A' , 'B' , 'B' ], }) And let’s declare our list of key columns. def merge_in_counts ( pipeline : ViewRepresentation ,…from win-vector.com

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