其R中的名字传递参数的函数 [英] Passing arguments to a function by their names in R
问题描述
我有2个数据帧:
a=c("aaaa","aaaaa", "aaaaaaaa")
b=c(3,5,6)
sample1=data.frame(a,b)
a=c("bb","bbbb","bbbbbbb")
b=c(4,6,54)
sample2=data.frame(a,b)
我想通过样品环路,并通过这些dataframes列某些功能如NCHAR(SAMPLE1 $ B)
I want to loop through the samples and pass the columns from these dataframes to some functions e.g. nchar(sample1$b)
所以使用什么应该在for循环做到这一点?下面的code不工作...对不起它的工作,但如长度SAMPLE1 $ B字符串印刷
So using what should go in the for loop to do this? The code below does not work... sorry it does work but the length of e.g. "sample1$b" string is printed
for(i in 1:2) {
cat(nchar(eval(paste("sample",i,"$b"))))
}
感谢
推荐答案
像MrFlick建议,你应该保存相关dataframes在一个列表:
Like suggested by MrFlick, you should store the related dataframes in a list:
samples <- list(sample1, sample2)
这可以让你避免它的名字指的是每个数据帧:
This allows you to avoid referring to each dataframe by its name:
lapply(samples, function(smp) nchar(smp$b))
如果你真的想使用独立的变量(你不应该!),你可以使用 GET
通过构建它的名字返回对象:
If you really want to use separate variables (you shouldn't!) you can use get
to return the object by constructing its name:
for (i in 1:2) print(nchar(get(paste0("sample", i))$b))
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