On 29/08/2020 11:34 a.m., Sigbert Klinke wrote:
Hi,
if I create a list with
l <- list(1:3, as.numeric(1:3), c(1,2,3))
and applying
lapply(l, 'class')
lapply(l, 'mode')
lapply(l, 'storage.mode')
lapply(l, 'typeof')
identical(l[[2]], l[[3]])
then I would believe that as,numeric(1:3) and c(1,2,3) are identical
objects. However,
lapply(l, serialize, connection=NULL)
returns different results for each list element :(
Any ideas, why it is like that?
Objects like 1:3 are stored in a special compact form, where 1:3 takes
up the same space as 1:1000000. Apparently as.numeric() knows to work
with that special form, and produces the numeric version of it.
You can confirm this by looking at the results of
serialize(l[[i]], connection=stdout(), ascii=TRUE)
for each of i=1,2,3:
> for (i in 1:3) {
+ cat("\nElement", i, "\n")
+ serialize(l[[i]], connection=stdout(), ascii=TRUE)
+ }
Element 1
A
3
262146
197888
5
UTF-8
238
2
1
262153
14
compact_intseq
2
1
262153
4
base
2
13
1
13
254
14
3
3
1
1
254
Element 2
A
3
262146
197888
5
UTF-8
238
2
1
262153
15
compact_realseq
2
1
262153
4
base
2
13
1
14
254
14
3
3
1
1
254
Element 3
A
3
262146
197888
5
UTF-8
14
3
1
2
3
Notice how element 1 is a "compact_intseq" and element 2 is a
"compact_realseq".
Duncan Murdoch
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