Find string in data.frame

Question

How do I search for a string in a data.frame? As a minimal example, how do I find the locations (columns and rows) of \'horse\' in this data.frame?

Answer 1

What about:

which(df == "horse", arr.ind = TRUE)
#      row col
# [1,]   2   1
# [2,]   3   1
# [3,]   5   2
# [4,]   4   3