Ordering Merged data frames

Question

As a fairly new R programmer I seem to have run into a strange problem - probably my inexperience with R

After reading and merging successive files into a single dat

Answer 1

Check whether z$lab_id is a factor (with is.factor(z$lab_id)).

If it is, try

z$lab_id <- as.character(z$lab_id)

if it is supposed to be a character vector; or

z$lab_id <-    as.numeric(as.character(z$lab_id))

if it is supposed to be a numeric vector.

Then order it again.

Ps. I had previously put these in the comments.