creating list of column with regular expression

[str_guru]

I want to create a list of column with regular expression for example.

patt <- "col.1_"

now i want to create a list of column names which can fetch names from data frame like.

("col.1_1","col.1_2","col.1_3",.......)  but it should exclude column names like col.1_1id, col.1_2id etc

[FJCC]

I am not sure exactly what names you want to include and exclude. In the following code, column names can have a single number after the underscore.

DF <- data.frame(col.1_1 = 1, col.1_1id = 3, 
                  col.1_2 = 2, col.1_2id = 5)
grep(pattern = "col.1_\\d$", colnames(DF), value = TRUE)
[1] "col.1_1" "col.1_2"