Thank you guys - it's a great learning: 'summarise_each' and 'funs'
On Tue, Jun 16, 2015 at 3:47 PM, Hadley Wickham <h.wick...@gmail.com> wrote:
> On Tue, Jun 16, 2015 at 12:24 PM, Dimitri Liakhovitski
> <dimitri.liakhovit...@gmail.com> wrote:
>> Hello!
>>
>> I have a data frame:
>>
>> md <- data.frame(a = c(3,5,4,5,3,5), b = c(5,5,5,4,4,1), c = c(1,3,4,3,5,5),
>> device = c(1,1,2,2,3,3))
>> myvars = c("a", "b", "c")
>> md[2,3] <- NA
>> md[4,1] <- NA
>> md
>>
>> I want to count number of 5s in each column - by device. I can do it like
>> this:
>>
>> library(dplyr)
>> group_by(md, device) %>%
>> summarise(counts.a = sum(a==5, na.rm = T),
>> counts.b = sum(b==5, na.rm = T),
>> counts.c = sum(c==5, na.rm = T))
>>
>> However, in real life I'll have tons of variables (the length of
>> 'myvars' can be very large) - so that I can't specify those counts.a,
>> counts.b, etc. manually - dozens of times.
>>
>> Does dplyr allow to run the count of 5s on all 'myvars' columns at once?
>
> md %>%
> group_by(device) %>%
> summarise_each(funs(sum(. == 5, na.rm = TRUE)))
>
> Hadley
>
> --
> http://had.co.nz/
--
Dimitri Liakhovitski
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