I am new to R, I have this massive data file with a list of user IDs. I want to replace those user IDs with a number i starting from 1 for each id. Is this possible?
Here's what I have:
Here's what I want:
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3Please use `dput` to show the examples instead of images as we can't copy it – akrun May 08 '18 at 13:42
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My guess is that the final solution will contain something along the lines of `as.numeric(factor(c("jeroen", "akrun", "roman")))`. – Roman Luštrik May 08 '18 at 13:46
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solution by adding in a new column: df$identifier <- as.numeric(as.factor(df$id)) – Jeroen May 08 '18 at 14:00
2 Answers
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Try this solution using a as.factor approach:
In df you have your input data:
df<-data.frame(ID=c(7001,7001,8001,8002),A=c(1,2,3,4))
df
ID A
1 7001 1
2 7001 2
3 8001 3
4 8002 4
Replace ID
df$ID<-as.numeric(as.factor(df$ID))
df
ID A
1 1 1
2 1 2
3 2 3
4 3 4
Terru_theTerror
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We can use match to get the index in the order of occurence of the unique ID's
dat$ID <- with(dat, match(ID, unique(ID)))
dat$ID
#[1] 1 1 2 3
Or use .GRP from data.table
library(data.table)
setDT(dat)[, ID := .GRP, ID]
Update
Based on the OP's description,
dat$ID <- cumsum(c(TRUE, diff(dat$E) < 0))
