Verify that column names in a data frame are not already present

In the Recca package, many functions add columns to an existing data frame. If the incoming data frame already contains columns with the names of new columns to be added, a name collision could occur, deleting the existing column of data. This function provides a way to quickly check whether newcols are already present in .DF.

verify_cols_missing(.DF, newcols)

Arguments

.DF	the data frame to which newcols are to be added
newcols	a single string, a single name, a vector of strings representing the names of new columns to be added to .DF, or a vector of names of new columns to be added to .DF

Value

NULL. This function should be called for its side effect of checking the validity of the names of newcols to be added to .DF.

Details

This function terminates execution if a column of .DF will be overwritten by one of the newcols.

Examples

df <- data.frame(a = c(1,2), b = c(3,4))
verify_cols_missing(df, "d") # Silent. There will be no problem adding column "d".
newcols <- c("c", "d", "a", "b")
if (FALSE) verify_cols_missing(df, newcols) # Error: a and b are already in df.