Rename columns of a data frame by searching column name

Question

I am writing a wrapper to ggplot to produce multiple graphs based on various datasets. As I am passing the column names to the function, I need to rename the column names so tha

Answer 1

> names(df)[grep("^col", names(df))] <- 
                        paste("new", names(df)[grep("^col", names(df))], sep="_")
> names(df)
[1] "new_col1" "new_col2" "new_col3"

If you want to replace an ordered set of column names with an arbitrary character vector, then this should work:

names(df)[sapply(oldNames, grep, names(df) )] <- newNames

The sapply()-ed grep will give you the proper locations for the 'newNames' vector. I suppose you might want to make sure there are a complete set of matches if you were building this into a function.

Answer 2

require(plyr)
df <- data.frame(col2=1:3,col1=3:5,col3=6:8)
df <- rename(df, c("col1"="new_col1", "col2"="new_col2", "col3"="new_col3"))
df

And you can be creative in making that second argument to rename so that it is not so manual.

Answer 3

hmm, this might be way to complicated, but the first that come into my mind:

lookup <- data.frame(search = c(col3_search,col2_search,col1_search),
                     replace = c(col3_replace,col2_replace,col1_replace))

colnames(df) <- lookup$replace[match(lookup$search, colnames(df))]

Answer 4

I second @justin's aes_string suggestion. But for future renaming you can try.

require(stringr)
df <- data.frame(col1=1:3,col2=3:5,col3=6:8)
oldNames <- c("col1", "col2", "col3")
newNames <- c("new_col1", "new_col2", "new_col3")
names(df) <- str_replace(string=names(df), pattern=oldNames, replacement=newNames)