I have a dataframe db1 with say 30 variables. Out of these 30, ten have sequential names - X1, X2,....X10. All these X variables are characters. I wanted to concatenate all of them. So I could of course do
db1$new <- paste(X1, X2, X3, X4, X5, X6, X7, X8, X9, X10)
But, this is not fun, and if I have a new file with different number of X variables, this code will not work. So, I need some method that concatenates using the variable name. I tried
zz1 <- paste(grep('^X',names(db1), value = TRUE))
zz2 <- paste("db1$",zz1,sep="",collapse = ",")
The second statement is to get the variable names seperated by commas. I then tried merging using
db1$new <- paste(db1$Terms,zz2,collapse = ","))
This did not work as R did not understand the zz2 were file names. What can I do?
Use do.call with paste0, like this, Using the dataset like below(Using @MKR data):
df <- structure(list(id = 1:2, X1 = c("a", "b"), X2 = c("a", "b"),
X3 = c("a", "b")), .Names = c("id",
"X1", "X2", "X3"), row.names = c(NA, -2L), class = "data.frame")
df$pastecol = do.call("paste0",df[,grep("^X\\d+$",names(df))])
Output:
#> df$pastecol = do.call("paste0",df[,grep("^X\\d+$",names(df))])
#> df
# id X1 X2 X3 pastecol
#1 1 a a a aaa
#2 2 b b b bbb