CODEWITHSUNDEEP
r
Miha
Miha

Reputation: 2884

Find length by subsetting or using %in%

I have a data.frame "df":

df

  id.number         names
1        102  Program ID 1
2        102  Program ID 1
3         11  Program ID 1
4         11  Program ID 1
5       1293  Program ID 1
6       1293  Program ID 1
7        132  Program ID 1
8        143  Program ID 1
9        143  Program ID 1
10       143  Program ID 1
11       143 Program ID 22
12       143 Program ID 22
13       143 Program ID 22
14       155 Program ID 22
15       155 Program ID 22
16      1552 Program ID 22
17      1553 Program ID 22

And vector: name_1 <- "Program ID 1"

Now I would like to find the unique length of "id.number" by "Program ID 1" and by matching with vector "name_1". I can find the unique length of "id.number" by "Program ID 1" with

length(unique(id.number[names=="Program ID 1"]))

But I would like to find unique length by matching my vector with column "names" in the data.frame "df".

So I need (and would like) to use something like that:

length(unique(subset(....)

or 

length(unique(subset .... %in% names_1

And my output should be the unique length/(number) in column "id.number" and not data table nor list.

Desired Output: just number, and in my case this is: 5 which is also the result of code length(unique(id.number[names=="Program ID 1"])).

Upvotes: 1

Views: 104

Answers (1)

plannapus
plannapus

Reputation: 18759

As stated in the comments, you just need to wrap your code that worked on vectors into a with(df, ...) statement:

with(df, length(unique(id.number[names=="Program ID 1"])))

Or to generalize to cases when name_1 contains several names:

with(df, length(unique(id.number[names%in%name_1])))

Upvotes: 1

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