How to find indices of element in one vector in other vector R

Question

I have two vectors, let's say

a <-  c('Q1', 'Q2', 'Q3')

and

b <- c('Q10', 'Q13', 'Q1', 'Q1', 'Q40', 'Q2', 'Q2', 'Q2')

Now I want to find the indices of the elements in a in b. So the result should be [3, 4, 6, 7, 8]. I tried to to it with match(a, b), but this results in only the first occurrence of a in b so [3, 6].

Does anyone know how to do this in R?

Could you please post your sample vectors in valid R syntax? E.g., `a = c("Q1", "Q2", "Q3")` — Gregor Thomas, Mar 05 '20 at 16:14
Also see [this](https://stackoverflow.com/q/1169388/5325862) and [this](https://stackoverflow.com/q/7530765/5325862) — camille, Mar 05 '20 at 16:27

score 3 · Accepted Answer · edited Mar 05 '20 at 16:16

3

a <-  c('Q1', 'Q2', 'Q3')
b <- c('Q10', 'Q13', 'Q1', 'Q1', 'Q40', 'Q2', 'Q2', 'Q2')

which(b %in% a)

[1] 3 4 6 7 8

edited Mar 05 '20 at 16:16

Gregor Thomas

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answered Mar 05 '20 at 16:14

Mr.Rlover

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Just to add to your answer for OP. ``match()`` was not working because ``match()`` returns a vector of the positions of (first) matches of its first argument in its second as read in the R Documentation. – Gainz Mar 05 '20 at 16:16

How to find indices of element in one vector in other vector R

1 Answers1