find var in a data frame and return next element in same row

Question

ultimately, I need to search column 1 of my data frame and if I find a match to var, then I need to get the element next to it in the same row (the next column over)

I thought I could usematch or %in% to find the index in a vector I got from the data frame, but I keep getting NA

one example I looked at is Is there an R function for finding the index of an element in a vector?, and I don't understand why my code is any different from the answers.

so in my code below, if I find b in column 1, I eventually want to get 20 from the data frame.

What am I doing wrong? I would preferr to stick to r-base packages if possible

> df = data.frame(names = c("a","b","c"),weight = c(10,20,30),height=c(5,10,15))
> df
  names weight height
1     a     10      5
2     b     20     10
3     c     30     15
> vect = df[1]
> vect
  names
1     a
2     b
3     c
> match("b", vect)
[1] NA

`vect` is a data frame. Try `vect = df[[1]]` or `with(df, weight[match("b", names)])` — Rich Scriven, Oct 28 '17 at 05:31
I thought I tried `df[[1]]` before, but yea, both of those work perfectly. Thanks for showing me how to retrieve the data i need in one line. Impressive! — Brian W, Oct 28 '17 at 05:42
Just to add another alternative: `df[df$names == "b", "weight"]` — Mikko Marttila, Oct 28 '17 at 08:14

find var in a data frame and return next element in same row

0 Answers0