Convert a row of a data frame to vector

125

I want to create a vector out of a row of a data frame. But I don't want to have to row and column names. I tried several things... but had no luck.

This is my data frame:

> df <- data.frame(a=c(1,2,4,2),b=c(2,6,2,1),c=c(2.6,8.2,7.5,3))
> df
  a b   c
1 1 2 2.6
2 2 6 8.2
3 4 2 7.5
4 2 1 3.0

I tried:

> newV <- as.vector(df[1,])
> newV
  a b   c
1 1 2 2.6

But I really want something looking like this:

> newV <- c( 1,2,2.6)
> newV
[1] 1.0 2.0 2.6

This question is tagged with r vector dataframe

~ Asked on 2013-01-23 16:39:29

The Best Answer is


166

When you extract a single row from a data frame you get a one-row data frame. Convert it to a numeric vector:

as.numeric(df[1,])

As @Roland suggests, unlist(df[1,]) will convert the one-row data frame to a numeric vector without dropping the names. Therefore unname(unlist(df[1,])) is another, slightly more explicit way to get to the same result.

As @Josh comments below, if you have a not-completely-numeric (alphabetic, factor, mixed ...) data frame, you need as.character(df[1,]) instead.

~ Answered on 2013-01-23 16:42:50


47

I recommend unlist, which keeps the names.

unlist(df[1,])
  a   b   c 
1.0 2.0 2.6 

is.vector(unlist(df[1,]))
[1] TRUE

If you don't want a named vector:

unname(unlist(df[1,]))
[1] 1.0 2.0 2.6

~ Answered on 2013-01-23 16:49:23


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