CODEWITHSUNDEEP
r
POTENZA
POTENZA

Reputation: 1437

How to Create a Column of Ranks While Grouping in R

I am using R and I want to create a column showing a sequence or rank, while grouping by two factors (hhid and period).

For example, I have this data set:

hhid perid
1000 1     
1000 1
1000 1
1000 2
1000 2
2000 1
2000 1
2000 1
2000 1
2000 2
2000 2

I want to add a column called "actno" like this:

hhid perid actno
1000 1     1
1000 1     2
1000 1     3
1000 2     1
1000 2     2
2000 1     1
2000 1     2
2000 1     3
2000 1     4
2000 2     1
2000 2     2

Upvotes: 2

Views: 1877

Answers (5)

Superbest
Superbest

Reputation: 26612

Pseudocode:

For each unique value of `hhid` `h`
    For each unique value of `perid` `p`
        counter = 0;
        For each row of table where `hhid==h && perid==p`
            counter++;
            Assign counter to `actno` of this column

Should be trivial to implement, especially with a data frame.

Upvotes: -4

mnel
mnel

Reputation: 115390

If you have lots of groups or large data, data.table is the way to go for efficiency of time and memory

# assuming your data is in a data.frame called DF
library(data.table)
DT <- data.table(DF)


DT[, ActNo := seq_len(.N), by = list(hhid,perid)]

note that .N gives the number of rows in the subset by grouping (see ?data.table for more details)

Upvotes: 4

IRTFM
IRTFM

Reputation: 263352

No need for plyr. Just use ave and seq:

> dat$actno <- with( dat, ave(hhid, hhid, perid, FUN=seq))
> dat
   hhid perid actno
1  1000     1     1
2  1000     1     2
3  1000     1     3
4  1000     2     1
5  1000     2     2
6  2000     1     1
7  2000     1     2
8  2000     1     3
9  2000     1     4
10 2000     2     1
11 2000     2     2

The first argument in this instance could be either column or you could do it with the slightly less elegant bu perhaps more clear: 

dat$actno <- with( dat, ave(hhid, hhid, perid, FUN=function(x) seq(length(x) ) ) )

Upvotes: 3

user1317221_G
user1317221_G

Reputation: 15441

if your data is called urdat then without plyr you can do:

df <- urdat[order(urdat$hhid, urdat$perid),]
df$actno <- sequence(rle(df$perid)$lengths)

Upvotes: 2

Justin
Justin

Reputation: 43255

the plyr package can do this nicely:

library(plyr)
dat <- structure(list(hhid = c(1000L, 1000L, 1000L, 1000L, 1000L, 2000L, 
2000L, 2000L, 2000L, 2000L, 2000L), perid = c(1L, 1L, 1L, 2L, 
2L, 1L, 1L, 1L, 1L, 2L, 2L)), .Names = c("hhid", "perid"), class = "data.frame", row.names = c(NA, 
-11L))

ddply(dat, .(hhid, perid), transform, actno=seq_along(perid))

   hhid perid actno
1  1000     1     1
2  1000     1     2
3  1000     1     3
4  1000     2     1
5  1000     2     2
6  2000     1     1
7  2000     1     2
8  2000     1     3
9  2000     1     4
10 2000     2     1
11 2000     2     2

Upvotes: 1

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