问题描述
exclude <- function(df,...) {
dots <- rlang::enquos(...)
for(i in 1:length(dots)) {
df <- exclude_cycle(df,dots[[i]])
}
return(df)
}
exclude_cycle <- function(df,condition) {
df <- dplyr::filter(df,!!condition)
print(paste(nrow(df),"records left after excluding",eval(condition),sep = " "))
return(df)
}
我希望print(paste(nrow(df),sep = " "))
打印一个看起来像100000 records left after excluded age > 18
的简单字符串,其中age > 18
是我直接传递给exclude
函数的过滤器:
exclude(df,age > 18)
我最终得到的输出类似于:
[1] "100000 records left after excluding ~" "100000 patients left after excluding age >= 18"
这与我想要的非常接近,但是每个字符向量打印两个字符串而不是1。如何获得所需的输出?
解决方法
您可以使用rlang::enexprs
允许在单个函数中将多个条件传递给点。另外,如果要排除条件,请记住要反转过滤器:
exclude <- function(df,...) {
dots <- rlang::enexprs(...)
for(i in seq_along(dots)){
df <- dplyr::filter(df,!(!!(dots[[i]])))
cat(nrow(df),"records left after excluding",as.character(dots[i]),"\n")
}
}
例如:
df <- data.frame(letters = rep(LETTERS[1:3],10),numbers = 1:30)
exclude(df,letters == "A",numbers < 15)
#> 20 records left after excluding letters == "A"
#> 11 records left after excluding numbers < 15
,
这是一个选择
exclude_cycle <- function(df,condition) {
df <- dplyr::filter(df,!!condition)
print(paste(nrow(df),as.list(eval(condition))[-1],sep = " "))
return(df)
}
-测试
exclude(df,age > 18)
#[1] "2 records left after excluding age > 18"
# age
#1 42
#2 19
数据
df <- data.frame(age = c(42,19,3))