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I have a list (tmpList), which looks like this:

$op [1] "empty" $termset $termset$field [1] "entry" $termset[[2]] $termset[[2]]$explode [1] "Y"

This is a list with a list inside. If I add this list to a vector

theOneVector = c(theOneVector, tmpList)

Now the resulting vector is of the length 2, because the first entry ("op") of the list is separated from the tmpList. Is it possible to append the complete tmpList into this vector?
I already tried it with

theOneVector = c(theOneVector, list(tmpList))

which gives a vector with the length of 1, but it is very cumbersome to access the elements of the list with this extra list around the list. (Too much list in one sentence I think.)

Any help would be appreciated,
Martin

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18

You can stick a vector (a restricted structure where all components have to be of the same type) into a list (unrestricted).

But you cannot do the reverse. Use lists of lists of lists ... and then use lapply et al to extract.

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I think it is because R's vector can only have a certain type of "mode"s: numeric, character, logical, complex etc but it cannot have elements of list type. So in this sense, R's vector is very different than python's list. The latter can store elements of arbitrary type.
Yes, we know. That part is covered by R's list type, just as my answered said seven years ago.
So @wiswit: Your downvote is just plain wrong. In R, only one data structure can hold different types: list. Which is what I said seven years ago. Blaming me for (by design) limitations of vector just shows your misunderstanding.
@ Dirk Eddelbuettel: Surely I benefit from your answer, sorry, the down voting is just a mistake. Any way you know to repair this?
@wiswit: Oh, no worries if it was inadvertent. You may be able to just click on the down-arrow.
1

the expression 'c(theOneVector, list(tmpList))' actually didn't return a vector of length 1, it returned a list (by coersion) because the items in a vector must all be of the same mode (data type).

Here's what you can do to create a container in R that will hold items of different mode and whose items are easy to access:

# create the container (an R 'list') vx = vector(mode="list") # create some items having different modes to put in it item1 = 1:5 item2 = "another item" item3 = 34 item4 = list(a = c(1:5), b = c(10:15)) # now fill the container vx$item1 = item1 vx$item2 = item2 vx$item3 = item3 vx$item4 = item4 # access the items in the container by name: vx$item1 # returns: [1] 4 5 6 vx$item2 # returns: [1] "another item"
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Or less verbosely: v1 <- list(item1 = 1:5, item2 = "another item", item3 = 34, item4 = list(a = c(1:5), b = c(10:15))`
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I think a list() of list() is what you want.

Here is a simple example with lapply() which shows how to use them. Note that lapply() will apply the function provided to each element of the list given in argument and return a list containing the results of the individual executions.

> l1 = list(a = 10, b = 11) > l2 = list(a = 20, b = 22) > test_function <- function(l){ return(paste("a =", l$a, "b = ", l$b, "\n")) } # Do something to each element of the list # (i.e.: apply a function test_function() using lapply()). # This will return a list over which you can iterate. # Each individual list l1 and l2 is "wrapped" into a single list: list(l1, l2) > res = lapply(X = list(l1, l2), FUN = test_function) > res [[1]] [1] "a = 10 b = 11 \n" [[2]] [1] "a = 20 b = 22 \n" # First element of the results > res[1] [1] "a = 10 b = 11 \n" # Second element of the results > res[2] [1] "a = 20 b = 22 \n"
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