Changing column names of a data frame
Changing column names of a data frame
Question
I have a data frame called "newprice" (see below) and I want to change the column names in my program in R.
> newprice
Chang. Chang. Chang.
1 100 36 136
2 120 -33 87
3 150 14 164
In fact this is what am doing:
names(newprice)[1]<-paste("premium")
names(newprice)[2]<-paste("change")
names(newprice)[3]<-paste("newprice")
I have not put this in a loop because I want each column name to be different as you see.
When I paste my program into R console this is the output it gives me:
> names(newprice)[1]<-paste(“premium”)
Error: unexpected input in "names(newprice)[1]<-paste(“"
> names(newprice)[2]<-paste(“change”)
Error: unexpected input in "names(newprice)[2]<-paste(“"
> names(newprice)[3]<-paste(“newpremium”)
Error: unexpected input in "names(newprice)[3]<-paste(“"
I have equally tried using the c() function-for example c("premium"), instead of the paste() function, but to no avail.
Could someone help me to figure this out?
Popular Answer
Use the colnames() function:
R> X <- data.frame(bad=1:3, worse=rnorm(3))
R> X
bad worse
1 1 -2.440467
2 2 1.320113
3 3 -0.306639
R> colnames(X) <- c("good", "better")
R> X
good better
1 1 -2.440467
2 2 1.320113
3 3 -0.306639
You can also subset:
R> colnames(X)[2] <- "superduper"
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I use this:
colnames(dataframe)[which(names(dataframe) == "columnName")] <- "newColumnName"
The error is caused by the "smart-quotes" (or whatever they're called). The lesson here is, "don't write your code in an 'editor' that converts quotes to smart-quotes".
names(newprice)[1]<-paste(“premium”) # error
names(newprice)[1]<-paste("premium") # works
Also, you don't need paste("premium") (the call to paste is redundant) and it's a good idea to put spaces around <- to avoid confusion (e.g. x <- -10; if(x<-3) "hi" else "bye"; x).
The new recommended way to do this is to use the setNames function. See
?setNames. Since this creates a new copy of the data.frame, be sure to assign the result to the original data.frame, if that is your intention.
data_frame <- setNames(data_frame, c("premium","change","newprice"))
Newer versions of R will give you warning if you use colnames in some of the ways suggested by earlier answers.
If this were a data.table instead, you could use the data.table function setnames, which can modify specific column names or a single column name by reference:
setnames(data_table, "old-name", "new-name")
I had the same issue and this piece of code worked out for me.
names(data)[names(data) == "oldVariableName"] <- "newVariableName"
In short, this code does the following:
names(data) looks into all the names in the dataframe (data)
[names(data) == oldVariableName] extracts the variable name (oldVariableName) you want to get renamed and <- "newVariableName" assigns the new variable name.