How could I change the transparency of the a density plot in ggpairs function (GGally)

Question

[pr.khavari]

Hi everyone I want to draw a transparent density plot by ggpairs function which combined with gglot2. However, it gives me an error.

ggpairs(main_data_2,columns = 2:4, title = "Scatterplot Matrix of the Distribution of Metorological parameters and Pomological traits", ggplot2::aes(colour=Cultivar))

Do you have any suggestions?

[ATpoint]

This is not bioinformatics-related and might get closed. In general, as this seems to be ggplot, I recommend to google for ggplot plus the keyword you are after. That usually gives threads at StackOverflow to start with. As you do not post example data or the error message there is not much more to say at this point. It is good practice to include code, example data and the error message. Example data e.g. using dput().