Iterate over list to get value by its name

Question

This works. But are there more efficient/simpler ways to get output?

test_list <- list(list("name"="A","property"=1),
              list("name"="B","property"=2),
              list("name"="C","property"=3))

myFunction <- function(arg1=NULL, arg2=NULL){
  arg1[[arg2]]
}

# works
output <- sapply(test_list, myFunction, "property")

# returns NULL 
# output <- sapply(test_list, `$`, "property")

`sapply(test_list, '[[', "property")` or `sapply(test_list, getElement, name="property")` — jogo, May 24 '18 at 13:35

score 2 · Accepted Answer · answered May 24 '18 at 13:33

2

We can specify the anonymous function call to do the extraction

sapply(test_list, function(x) x$property)
#[1] 1 2 3

answered May 24 '18 at 13:33

akrun

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1

I missed out on the x argument. Thanks. – nilsole May 24 '18 at 13:34
Generally one should avoid using "$" inside functions, so a better answer would use: `function(x) x[['property']]` – IRTFM Sep 19 '18 at 18:16

Iterate over list to get value by its name

1 Answers1

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