Do a partition over using dplyr in R

Asked May 16 '16 at 13:15

Active May 16 '16 at 13:15

Viewed 341 times

I am looking to use dplyr in order to construct an observation count, much the same way in which SQL would use a partition over function. It must specifically be dplyr due to its speed when handling big data structures

Imagine we have a dataset as follows:

>Letters
A
A
A
B
B
A
B
C
C
D
A
C

And I want to get something as follows:

Letters Count
A   1
A   2
A   3
B   1
B   2
A   4
B   3
C   1
C   2
D   1
A   5
C   3

Any suggestions?

asked May 16 '16 at 13:15

Hanjo Odendaal

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6

Try `df1 %>% group_by(Letters) %>% mutate(Count = row_number())` – akrun May 16 '16 at 13:16
You are fast....was answering. :) – Gopala May 16 '16 at 13:18
1

Or `ave(Letters,Letters,FUN=seq_along)`. – nicola May 16 '16 at 13:19
I can see how this question can be seen as a duplicate. But as this question specifically asks for a `dplyr` variation in the application (other answers use `data.table`), I will leave it for now. – Hanjo Odendaal May 16 '16 at 13:26

Do a partition over using dplyr in R

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