Create dataframe based on matching

Question

I want to create a df in R with two variables, they have different number of rows. This is an abstract example: I want to match a 3 to "Fail" (without writing in manually, I know that I could just write the 3 in a on the third place). So first assign 3 to Fail, than match 1 to Test, 2 to Test, 4 to Success and 5 to Test by skipping Fail.

a <- c(1,2,4,5)
b <- c("Test", "Test", "Fail", "Success", "Test")
data.frame(a,b)

So the following steps would be important:

1st: find string "Fail": assign a certain value to it (here 3)

2nd: create a df with a and b

3rd: final result should look like this:

a	b
1	Test
2	Test
3	Fail
4	Success
5	Test

what determines a test, fail and success? how is `a` generated — Mike, May 13 '22 at 13:05
[Relevant](https://stackoverflow.com/questions/1493969/how-to-insert-elements-into-a-vector) — Sotos, May 13 '22 at 13:08

Maël · Answer 1 · 2022-05-13T13:10:50.690

1

idx <- which(b == "Fail")
a <- append(a, idx, after = idx - 1)
#[1] 1 2 3 4 5

data.frame(a, b)
  a       b
1 1    Test
2 2    Test
3 3    Fail
4 4 Success
5 5    Test

edited May 13 '22 at 13:10

answered May 13 '22 at 13:05

Maël

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Thanks that's what I wanted, does this work for multiple Rows as well? For example if I would like to have "Test" == 1 always? In this case a would be something like: a=c(3,4). 3 for Fail and 4 for Success – dlwhch May 13 '22 at 13:51
With a few tweaks it should work yes – Maël May 13 '22 at 14:02

score 0 · Answer 2 · answered May 13 '22 at 13:12

0

You don't need to create both vectors. If you are going with indexes, you can just do,

data.frame(a = seq_along(b), b = b)

  a       b
1 1    Test
2 2    Test
3 3    Fail
4 4 Success
5 5    Test

answered May 13 '22 at 13:12

Sotos

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Create dataframe based on matching

2 Answers2