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Regular Visitor

Convert coordinates lambert 93 {[Coordinate X],[Coordinate Y]} into Latitude and Longitude

Hello everyone,


It has been a few weeks I am using Power Query and Power BI, however there are still a very important amount of things I have to learn.


Usually when I am confronting an issue, I would find the answer through the community. However, I am now stuck with the following problem and I do think there is an answer with Python from what I read from other website.


However, I am totally unfamiliar with Python and I do hope there is another way to do it on Power Query.


Here is my issue, I have two columns {[Coordinate X],[Coordinate Y]}, which are in lambert 93 format for instance:


But Power BI seems to only accept latitude and longitude coordinates.

How can we convert it but massively both columns?

Indeed there is a website where you can do it one by one, but there are more than 100k rows

Convertisseur de coordonnées gratuit en ligne (


And another link I thought would help me was Python but my knowledge is for the moment too limited:

How to convert Lambert 93 to longitude and latitude with python 3 (


Many thanks in advance if someone could guide me!


Best regards

Super User
Super User

What system are converting the Lambert 93 coordinates into?  WGS84 or something else?

Hello @ronrsnfld ,


It would be WGS84 indeed to fit powerBI visualization.

Super User
Super User

Hi @Yrmouf 


It shouldn't be very complicated - have you tried asking ChatGPT for the solution?


"Give me the powerquery code to convert lambert projection to wgs"




If that doesn't work please get back here and I'll have a look.




Frequent Visitor

This is the most unhelpfull response I've ever seen.


"have you tried asking ChatGPT for the solution" ...


Oh boy, the humanity ....

Regular Visitor

Hi @ams1 ,


Thanks for your advice, I tried so, but the code does not seem to work, I ended up with the following code

    Source = #"RPLS", // replace <Table> with the name of your source table
    #"Added Custom" = Table.AddColumn(Source, "Lat_Long", each let
        x = [Coordonnée X], // replace [Coordonnée X] with the name of your Lambert X coordinate column
        y = [Coordonnée Y], // replace [Coordonnée Y] with the name of your Lambert Y coordinate column
        wgs84 = List.Transform(
                  CoordinateSystem.Transform( #"EPSG:2154", #"EPSG:4326", {x, y} ), 
                  each Number.Round(_, 7)
        lat = wgs84{0},
        long = wgs84{1}
    #"Expanded Lat_Long" = Table.ExpandListColumn(#"Added Custom", "Lat_Long"),
    #"Renamed Columns" = Table.RenameColumns(#"Expanded Lat_Long", {"Lat_Long", "Lat_Long_WGS"}),
    #"Expanded Lat_Long_WGS" = Table.ExpandListColumn(#"Renamed Columns", "Lat_Long_WGS"),
    #"Extracted Values" = Table.TransformColumns(#"Expanded Lat_Long_WGS", {{"Lat_Long_WGS", each Text.Combine(List.Transform(_, Text.From), ","), type text}}),
    #"Split Column by Delimiter" = Table.SplitColumn(#"Extracted Values", "Lat_Long_WGS", Splitter.SplitTextByDelimiter(",", QuoteStyle.Csv), {"Latitude", "Longitude"}),
    #"Changed Type" = Table.TransformColumnTypes(#"Split Column by Delimiter",{{"Latitude", type number}, {"Longitude", type number}})
    #"Changed Type"


 It looked like after prompting CHatgpt that 


 function is the source of the problem as it looks like I have to load a library, but I am not quite sure to do so when I looked into the one it adviced me to load but I guess I have to download from somewhere, but where to download it and where to load it?

Spatial = Extension.Load("Microsoft.Mashup.Engine1.Library.Spatial")


Also, why the code does not take into account the variable "Spatial"?

Many thanks for your help

Have a nice day

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