There is a solution but this need that your gird have always the same number of division of your final layout (always 5 division horizontal and 4 vertical). If you want to change it you only have to adapt the expression.
Principle
The goal is to calculate the position of the point in your layout based on the coordinate of your point and the map extent.
For example : you have a point that have Y coordinate = 105.
If your map max Y is 110 and min Y is 100 then your point will be in the center. If it is in the center then you should attribute the letter in the middle, if you go form A to E it should be C.
I assume you have 4 divisions in X with number from 1 to 4 and 5 division in Y with letter from A to E.
Expression
- Make sure the layer for your points is in the same CRS as you are using for your layout. In your layout name your map item
Carte 1 or change the name in the expression.
- Add an
attribute table with your point layer and set it to get only visible features.
- Add a column with the heading X and with the attribute based on the following expression :
with_variable( 'extent',
map_get( item_variables( 'Carte 1' ), 'map_extent' ),
ceil(($x -x_min(@extent)) / bounds_width(@extent)*4)
)
- Add a column with the heading Y and with the attribute based on the following expression :
with_variable( 'extent',
map_get( item_variables( 'Carte 1' ), 'map_extent' ),
char(64+ceil(($y -y_min(@extent)) / bounds_height(@extent)*5))
)
Result
Notes
The function with variable() define a temporary variable named extent to be used easier in the calculation.
The function ceil() permit to get 1 when we are between 0 and 1, 2 between 1 and 2.
The function char() is used to get letter based on asci code. If you do char(65) you get A, char (66) you get B. Combine with ceil it permit to get the letter you want based on number.
