How to remove dataframes where nrow

Question

I have a list of dataframes, ranging in size. I want to drop those with few rows (lets say <3).

This is what I've been working with so far, for what it's worth:

d1 <- data.frame(y1 = c(1, 2, 3, 9), y2 = c(4, 5, 6, 7))
d2 <- data.frame(y1 = c(3, 2, 1, 6), y2 = c(6, 5, 4, 4))
d3 <- data.frame(y1 = c(3, 2), y2 = c(6, 5))
d4 <- data.frame(y1 = c(3, 2), y2 = c(6, 5))
listdfs <- list(d1, d2, d3, d4)


listdfs2<-lapply(listdfs,function(x) if(nrow<10<-NULL)))

So basically d1 and 2 should be maintained.

Thanks.

A possible duplicate of https://stackoverflow.com/questions/6941506/subset-elements-in-a-list-based-on-a-logical-condition/8935399. — Majid, Oct 17 '19 at 13:03

score 3 · Answer 1 · answered Oct 17 '19 at 12:47

3

This can be done by Filter, i.e.

Filter(function(i) nrow(i) > 3, listdfs)

[[1]]
  y1 y2
1  1  4
2  2  5
3  3  6
4  9  7

[[2]]
  y1 y2
1  3  6
2  2  5
3  1  4
4  6  4

answered Oct 17 '19 at 12:47

Sotos

51,121
6
32
66

score 2 · Accepted Answer · answered Oct 17 '19 at 12:42

2

You can do:

listdfs[lapply(listdfs, nrow) > 3]

[[1]]
  y1 y2
1  1  4
2  2  5
3  3  6
4  9  7

[[2]]
  y1 y2
1  3  6
2  2  5
3  1  4
4  6  4

answered Oct 17 '19 at 12:42

Humpelstielzchen

6,126
3
14
34

`sapply` rather than `lapply` – jangorecki Oct 17 '19 at 16:12
what's he advantage in this case? – Humpelstielzchen Oct 17 '19 at 16:57
You want to supply to `<` a integer vector, not a list of integer scalars. – jangorecki Oct 17 '19 at 17:46

score 2 · Answer 3 · answered Oct 17 '19 at 12:47

2

Another option is to use discard from purrr

purrr::discard(listdfs, ~ nrow(.) < 3)

[[1]]
  y1 y2
1  1  4
2  2  5
3  3  6
4  9  7

[[2]]
  y1 y2
1  3  6
2  2  5
3  1  4
4  6  4

answered Oct 17 '19 at 12:47

Matt

2,947
1
9
21

How to remove dataframes where nrow

3 Answers3