CODEWITHSUNDEEP
rstata
Sam Marshal
Sam Marshal

Reputation: 85

Translating Stata to R - recoding

I am trying to translate the following from Stata

clear
set obs 1000
generate y = floor((10-0+1)*runiform() +0)
recode y (7=0) (8=0) (9=1) (10=2)

I thought I had it with the following code:

library(dplyr)
mydata <- y ~ floor((10-0+1)*runif(1000)+0)
recode (mydata, '7'=0, '8'=0, '9'=1, '10'=2)

However, the last line keeps giving me an error:

Error in UseMethod("recode"):no applicable method for 'recode' applied to an object of class "formula".

Any ideas?

Upvotes: 3

Views: 724

Answers (1)

Frank
Frank

Reputation: 66819

You can use cut:

n = 1000L
y = cut(runif(n, 0, 11), c(-Inf, 9, 10, Inf), right = FALSE, ordered = TRUE)

You can see how it worked with table:

# y
#  [-Inf,9)    [9,10) [10, Inf) 
#       813        91        96

If you really want the codes, you can use as.integer(y)-1L. Read ?cut and ?factor for more details on ordinal data in R.

I've been assuming so far that there is some rhyme or reason to the recoding rule. If there is not, best to store it in a separate table and draw values from there (which is the same thing I would do in Stata):

rec = data.frame(old = c(7,8,9,10), new = c(0,0,1,2))

n  = 1000L
y  = floor(runif(n, 0, 11))
DF = data.frame(id = 1:10, y)

library(data.table)
setDT(DF)

DF[rec, on=c(y = "old"), y := new]
DF[, .N, keyby=y]

#    y   N
# 1: 0 288
# 2: 1 179
# 3: 2 174
# 4: 3 101
# 5: 4  82
# 6: 5  93
# 7: 6  83

You'd need to install the data.table package for this to work, though.

Upvotes: 2

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