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Here's a reproducible example, with my explanation of why it does what it does. 

data = read.csv(text="Email foo.final bar.final
[email protected] 100       200
[email protected] 101       201
[email protected] 102       202
[email protected] 103       103", header=T, sep="" )

a = gather(data, key, Grade, -Email)

means: Except "Email", put the values of all the columns into a single new column called "Grade" and add a new column called "key" which contains the column header under which the value occurred. Given that we have 4 observations with two variables each, that should produce 8 observations. Result:

        Email       key Grade
1 [email protected] foo.final   100
2 [email protected] foo.final   101
3 [email protected] foo.final   102
4 [email protected] foo.final   103
5 [email protected] bar.final   200
6 [email protected] bar.final   201
7 [email protected] bar.final   202
8 [email protected] bar.final   103

b = gather(data, key, Grade)

Same meaning but now we include Email. Now we have 4 observations but with 3 variables, so we should get 12 observations. Result:

         key       Grade
1      Email [email protected]
2      Email [email protected]
3      Email [email protected]
4      Email [email protected]
5  foo.final         100
6  foo.final         101
7  foo.final         102
8  foo.final         103
9  bar.final         200
10 bar.final         201
11 bar.final         202
12 bar.final         103

I am not surprised.

halfer
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pitosalas
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    What were you expecting? Which part doesn't make sense to you? I'm not really sure what you are asking. Also, it's much better if you include a simple [reproducible example](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) when asking a question. A `str()` is less helpful than a `dput()`. Even better use a built in data set or a minimal, simple example. – MrFlick Jun 02 '17 at 13:49
  • This is very much expected right? You are gathering all variables (not escaping email) which coerces numeric/character values in a single column – timfaber Jun 02 '17 at 13:51
  • Are all of the emails actually the same? If not then you might want to reconsider the example you're giving since it doesn't represent your use case. – Dason Jun 02 '17 at 13:55
  • Fair enough, I am rewriting the whole question using a reproducible example and explaining what is surprising to me. – pitosalas Jun 02 '17 at 15:42

1 Answers1

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You may need to do something more like this 

f2 <- f1 %>% 
      gather(key = Assignment, value = Grade, COURSE.final:EXAM.final) %>%
      select(-email)
Matt Jewett
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