iferror equivalent in R

Question

Here is the simplified version:

Suppose I am using 'which' function to find a position, say -

position_num=which(df$word=="ABC")

If the value exists it is fine and it returns an integer, but in case it is unable to match it returns integer(0) in such a case I want to assign a default value to position_num=1.

Thanks for the help in advance

Thanks Brandon, can you please help me with a short example code how we can solve this with tryCatch. — Anurag H, Jan 31 '16 at 06:32
http://stackoverflow.com/questions/12193779/how-to-write-trycatch-in-r — Brandon Bertelsen, Jan 31 '16 at 06:34

Rich Scriven · Accepted Answer · 2016-01-31T01:47:00.443

5

Something like the following if() statement would probably do it.

position_num = if(!length(w <- which(df$word == "ABC"))) 1 else w

Here we are just checking to see if the result from which() has a length, because

length(integer(0))
# [1] 0

And we return 1 if it doesn't have a length, and the which() result (w) otherwise.

edited Jan 31 '16 at 01:47

answered Jan 30 '16 at 22:40

Rich Scriven

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This one is much better than mine, because: 1. It does not call ifelse, which can be time consuming 2. It calls which() only once – Paweł Sopel Jan 30 '16 at 22:42

score 1 · Answer 2 · answered Jan 30 '16 at 22:37

1

Would this work for you?

position_num=ifelse(length(which(df$word=="ABC")) != 0,which(df$word=="ABC"),1)

answered Jan 30 '16 at 22:37

Paweł Sopel

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Thanks Pawel for the assistance – Anurag H Jan 30 '16 at 22:48

iferror equivalent in R

2 Answers2