CODEWITHSUNDEEP
r
uncool
uncool

Reputation: 2703

dropping list objects containing NULL value

I have an list object below, which contains several NULL values. Now I would like to drop these and have a list without these values, but I can't really figure out the right syntax.

Now as I understand it a lapply loop would not work and I can't seem to get into their respective index list index number, I'm trying foo[[!is.null(foo)]] <- NULL but this gives me the list objects while the NULL values it contained within, and foo[[]][!is.null(foo)] <- NULL doesn't work either.

List object

   Length Class      Mode
0    0     -none-     NULL
10  29     data.frame list
20  29     data.frame list
30  29     data.frame list
40  29     data.frame list
50  29     data.frame list
60  29     data.frame list
70  29     data.frame list
80  29     data.frame list
90  29     data.frame list
100 29     data.frame list
110 29     data.frame list
120 29     data.frame list
130 29     data.frame list
140 29     data.frame list
150  0     -none-     NULL
160  0     -none-     NULL
170  0     -none-     NULL
180  0     -none-     NULL
190  0     -none-     NULL
200  0     -none-     NULL
210  0     -none-     NULL
220  0     -none-     NULL
230  0     -none-     NULL
250  0     -none-     NULL
260  0     -none-     NULL
270  0     -none-     NULL
280  0     -none-     NULL
300  0     -none-     NULL
330  0     -none-     NULL

Upvotes: 2

Views: 74

Answers (1)

akrun
akrun

Reputation: 887168

You can use Filter to remove the NULL list elements

  Filter(Negate(is.null), lst)

data

 lst <- list(data.frame(1:5, 6:10), NULL, NULL, data.frame(1:10))

Upvotes: 4

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