How to rename a single column in a data.frame?

Question

I know if I have a data frame with more than 1 column, I can use

colnames(x) <- c("col1","col2")

to rename the columns. How do I do this if it's just one column? Meaning a vector or data frame with only one column in it.

Example:

trSamp <- data.frame(sample(trainer$index, 10000))

head(trSamp )

#   sample.trainer.index..10000.

# 1                      5907862

# 2                      2181266

# 3                      7368504

# 4                      1949790

# 5                      3475174

# 6                      6062879

ncol(trSamp)

# [1] 1

class(trSamp)

# [1] "data.frame"

class(trSamp[1])

# [1] "data.frame"

class(trSamp[,1])

# [1] "numeric"

colnames(trSamp)[2] <- "newname2"

# Error in names(x) <- value : 

#   'names' attribute [2] must be the same length as the vector [1]

Answer 1

To change the column name of a data frame with a single column, you can use the colnames() function as follows:

colnames(trSamp) <- "newname2"