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Dmitry_D's avatar
Dmitry_D
Frequent Visitor
9 years ago
Solved

Calculate nearest points by geographical coordinates

Hello!   I have two tables. Table "Customers address" with my customers id, latitude and longitude (8 mln rows). And "Shop_table" with my shops id, latitude and longitude (500 rows).   The goal i...
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  • Dmitry_D's avatar
    Dmitry_D
    9 years ago

    It seems, I figured how to do it

     

    I made the user function

     

    (reg,x_cast,y_cast)=>
    let
    Source = Table.SelectRows(shop,each [region]=reg),
    formula = Table.AddColumn(Sorce, "Distance", each
    6371 * 2 *Number.Asin(Number.Sqrt(Number.Power(Number.Sin((y_cast-[y_shop])*Number.PI/180/2),2)+Number.Cos(y_cast*Number.PI/180)*Number.Cos([y_shop]*Number.PI/180)*Number.Power(Number.Sin((x_cast-[x_shop])*Number.PI/180/2),2)))),
    minimum = List.Min(formula[Distance]),
    fnl_tbl= Table.SelectRows(formula,each [Custom]=minimum)
    in
    fnl_tbl

ImkeF's avatar
ImkeF
Community Champion
9 years ago

Yes , of course thats the best way as you don't have to group (and the tables to operate on are shorter).

How many times faster does it make your query?

Dmitry_D's avatar
Dmitry_D
Frequent Visitor
9 years ago

Input data

Customer_table = 13 mln rows

Shop_table = 540 rows

 

The 1st method (with Group) was endless. After 20 minutes of waiting I stopped id

The 2nd method (with user function) takes about 7 seconds