[R] level sets of factors are different

[Richard van Wingerden]

Hi,

I have two data frames A en B.
I want to filter B with values of A

data_frame_b
names <- colnames(data_frame_b[1:1, ])

filtera <- data.frame(data_frame_a[1:1])
	
	print(nrow(filtera))
	
	if (nrow(filtera)>0){
		
		filtered_frame_b <- subset(data_frame_b, ColumnX == filtera[1, 1], names)
         }
The results are:

[1] 124
Error in Ops.factor(ColumnX, filtera[1, 1]) :
        level sets of factors are different


What is wrong??

Richard