通过函数将子集参数传递给子集 [英] Pass subset argument through a function to subset

问题描述

我想要一个函数，它调用 subset，并传递一个 subset 参数:

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

我尝试使用 substitute，但无法找到正确的组合.我怎样才能让它工作?

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

推荐答案

A5C1D2H2I1M1N2O1R2T1 答案有效，但您可以通过简单地使用以下方法跳过整个解析/解析周期:

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))
}

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