Pass subset argument through a function to subset

user_299878 0
Viewed 5295

I would like to have a function which calls subset, and passes on a subset argument:

df <- data.frame(abc=c("A","A","B","B"),value=1:4)
subset(df,abc=="A")
## works of course:
#  abc value
#1   A     1
#2   A     2

mysubset <- function(df,ssubset)
  subset(df,ssubset)

mysubset(df,abc=="A")
## Throws an error
# Error in eval(expr, envir, enclos) : object 'abc' not found

mysubset2 <- function(df,ssubset)
  subset(df,eval(ssubset))

mysubset2(df,expression(abc=="A"))
## Works, but needs expression

I tried with substitute, but was not able to find the right combination. How can I get this working?

subset r
2 Answers

The A5C1D2H2I1M1N2O1R2T1 answer works, but you can skip the whole deparse/parse cycle by simply using:

mysubset <- function(df, p) {
  ps <- substitute(p)
  subset(df, eval(ps))
}
user_2195840
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