R - loop through multiple dataframes from a list of names

Question

I have a number of large DFs and I want to loop through them. Instead of binding them together to make a big list I thought I should make a simple vector with their names and look though them, but how can I do this?

For example I have:

DF1 <- data.frame(c("a", "b", "c"),c(TRUE, FALSE, TRUE))
DF2 <- data.frame(c("aa", "bb", "cc"),c(FALSE, FALSE, TRUE))
DF3 <- data.frame(c("aaa", "bbb", "ccc"),c(TRUE, FALSE, FALSE))

MyDFs <- c("DF1", "DF2", "DF3")

for (i in MyDFs) {
    print(nrow(i))
}

but the for loop does not work as R does not recognise them as the DFs, how can I correct this? also is this the best way to do this?

Your data.frames should be in a list to begin with.

Roland
– Roland

2014-08-21 11:48:34 +00:00
Commented Aug 21, 2014 at 11:48 — Roland
– Roland, Commented Aug 21, 2014 at 11:48

akrun · Accepted Answer · 2014-08-21 11:54:08Z

1

Or

 sapply(mget(MyDFs),nrow)
 #DF1 DF2 DF3 
 # 3   3   3

If you don't want to create a vector MyDFs

 sapply(mget(ls(pattern="DF")), nrow) #should also work

answered Aug 21, 2014 at 11:54

akrun

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Comments

Taher A. Ghaleb · Accepted Answer · 2018-12-05 00:31:56Z

0

In your own code, just replace print(nrow(i)) with print(nrow(get(i))), since i is: chr "DF1" etc.

for (i in MyDFs) {
     print(nrow(get(i)))
}
[1] 3
[1] 3
[1] 3

edited Dec 5, 2018 at 0:31

Taher A. Ghaleb

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answered Sep 11, 2014 at 4:32

rnso

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