Plz, I'm a beginner in R programming. I have an Excel with columns:
GridNUM, Long, Lat and Values 
So I want to plot this data grid in my shapefile like the example

Plz, I'm a beginner in R programming. I have an Excel with columns:
GridNUM, Long, Lat and Values 
So I want to plot this data grid in my shapefile like the example

 
    
    