Why is the class() of Sys.time() length 2?
The class() of all elements I've encountered in R have been of length 1.
Some examples
library(dplyr)
"string" %>% class %>% length
# [1] 1
123 %>% class %>% length
# [1] 1
0.234 %>% class %>% length
# [1] 1
Sys.Date() %>% class %>% length
# [1] 1
But the class() of Sys.time() (which is itself, like the examples above, length 1) is length 2
Sys.time() %>% class %>% length
# [1] 2
Why?
r
asked Jan 20 at 7:04
user5783745user5783745
9292521
add a comment |
The class() of all elements I've encountered in R have been of length 1.
Some examples
library(dplyr)
"string" %>% class %>% length
# [1] 1
123 %>% class %>% length
# [1] 1
0.234 %>% class %>% length
# [1] 1
Sys.Date() %>% class %>% length
# [1] 1
But the class() of Sys.time() (which is itself, like the examples above, length 1) is length 2
Sys.time() %>% class %>% length
# [1] 2
Why?
r
asked Jan 20 at 7:04
user5783745user5783745
9292521
Albeit a different class, adata.tablehas 2 classes, the answer from here might help to explain why: stackoverflow.com/a/15986236/2449656
– Khaynes
Jan 20 at 7:11
1
Also, see 13.6 from here: adv-r.hadley.nz/s3.html
– Khaynes
Jan 20 at 7:16
add a comment |
The class() of all elements I've encountered in R have been of length 1.
Some examples
library(dplyr)
"string" %>% class %>% length
# [1] 1
123 %>% class %>% length
# [1] 1
0.234 %>% class %>% length
# [1] 1
Sys.Date() %>% class %>% length
# [1] 1
But the class() of Sys.time() (which is itself, like the examples above, length 1) is length 2
Sys.time() %>% class %>% length
# [1] 2
Why?
r
asked Jan 20 at 7:04
user5783745user5783745
9292521
The class() of all elements I've encountered in R have been of length 1.
Some examples
library(dplyr)
"string" %>% class %>% length
# [1] 1
123 %>% class %>% length
# [1] 1
0.234 %>% class %>% length
# [1] 1
Sys.Date() %>% class %>% length
# [1] 1
But the class() of Sys.time() (which is itself, like the examples above, length 1) is length 2
Sys.time() %>% class %>% length
# [1] 2
Why?
r
r
asked Jan 20 at 7:04
user5783745user5783745
9292521
asked Jan 20 at 7:04
user5783745user5783745
9292521
asked Jan 20 at 7:04
user5783745user5783745
9292521
asked Jan 20 at 7:04
user5783745user5783745
9292521
asked Jan 20 at 7:04
user5783745user5783745
9292521
9292521
Albeit a different class, adata.tablehas 2 classes, the answer from here might help to explain why: stackoverflow.com/a/15986236/2449656
– Khaynes
Jan 20 at 7:11
1
Also, see 13.6 from here: adv-r.hadley.nz/s3.html
– Khaynes
Jan 20 at 7:16
add a comment |
Albeit a different class, adata.tablehas 2 classes, the answer from here might help to explain why: stackoverflow.com/a/15986236/2449656
– Khaynes
Jan 20 at 7:11
1
Also, see 13.6 from here: adv-r.hadley.nz/s3.html
– Khaynes
Jan 20 at 7:16
Albeit a different class, a
data.table has 2 classes, the answer from here might help to explain why: stackoverflow.com/a/15986236/2449656– Khaynes
Jan 20 at 7:11
Albeit a different class, a
data.table has 2 classes, the answer from here might help to explain why: stackoverflow.com/a/15986236/2449656– Khaynes
Jan 20 at 7:11
1
1
Also, see 13.6 from here: adv-r.hadley.nz/s3.html
– Khaynes
Jan 20 at 7:16
Also, see 13.6 from here: adv-r.hadley.nz/s3.html
– Khaynes
Jan 20 at 7:16
add a comment |
1 Answer
1
active
oldest
votes
https://stat.ethz.ch/R-manual/R-devel/library/base/html/class.html is worth a read
But in essence the ability for objects to have multiple classes allows their behavior to change in certain situations, as the order of the class vector determines the order in which methods are searched.
In the case you've observed simple objects tend to have a singular class.
Sys.time() returns a timestamp which is a bit more complex, various methods are implemented for the classes and these can differ. Therefore if one were to try the object in a context where a method exists in the second class only, it would use the second classes method.
To view the methods, try the following:
methods(class = "POSIXt")
methods(class = "POSIXct")
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
When an object has multiple classes, is there a rule for the order in which they're returned? The quick work around for what I'm doing presently might be to simply take the first result
– user5783745
Jan 20 at 21:21
Thanks for showingmethods()- very useful!
– user5783745
Jan 20 at 21:22
add a comment |
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1 Answer
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1 Answer
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active
oldest
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https://stat.ethz.ch/R-manual/R-devel/library/base/html/class.html is worth a read
But in essence the ability for objects to have multiple classes allows their behavior to change in certain situations, as the order of the class vector determines the order in which methods are searched.
In the case you've observed simple objects tend to have a singular class.
Sys.time() returns a timestamp which is a bit more complex, various methods are implemented for the classes and these can differ. Therefore if one were to try the object in a context where a method exists in the second class only, it would use the second classes method.
To view the methods, try the following:
methods(class = "POSIXt")
methods(class = "POSIXct")
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
When an object has multiple classes, is there a rule for the order in which they're returned? The quick work around for what I'm doing presently might be to simply take the first result
– user5783745
Jan 20 at 21:21
Thanks for showingmethods()- very useful!
– user5783745
Jan 20 at 21:22
add a comment |
https://stat.ethz.ch/R-manual/R-devel/library/base/html/class.html is worth a read
But in essence the ability for objects to have multiple classes allows their behavior to change in certain situations, as the order of the class vector determines the order in which methods are searched.
In the case you've observed simple objects tend to have a singular class.
Sys.time() returns a timestamp which is a bit more complex, various methods are implemented for the classes and these can differ. Therefore if one were to try the object in a context where a method exists in the second class only, it would use the second classes method.
To view the methods, try the following:
methods(class = "POSIXt")
methods(class = "POSIXct")
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
When an object has multiple classes, is there a rule for the order in which they're returned? The quick work around for what I'm doing presently might be to simply take the first result
– user5783745
Jan 20 at 21:21
Thanks for showingmethods()- very useful!
– user5783745
Jan 20 at 21:22
add a comment |
https://stat.ethz.ch/R-manual/R-devel/library/base/html/class.html is worth a read
But in essence the ability for objects to have multiple classes allows their behavior to change in certain situations, as the order of the class vector determines the order in which methods are searched.
In the case you've observed simple objects tend to have a singular class.
Sys.time() returns a timestamp which is a bit more complex, various methods are implemented for the classes and these can differ. Therefore if one were to try the object in a context where a method exists in the second class only, it would use the second classes method.
To view the methods, try the following:
methods(class = "POSIXt")
methods(class = "POSIXct")
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
https://stat.ethz.ch/R-manual/R-devel/library/base/html/class.html is worth a read
But in essence the ability for objects to have multiple classes allows their behavior to change in certain situations, as the order of the class vector determines the order in which methods are searched.
In the case you've observed simple objects tend to have a singular class.
Sys.time() returns a timestamp which is a bit more complex, various methods are implemented for the classes and these can differ. Therefore if one were to try the object in a context where a method exists in the second class only, it would use the second classes method.
To view the methods, try the following:
methods(class = "POSIXt")
methods(class = "POSIXct")
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
answered Jan 20 at 7:19
zacdavzacdav
3,5712829
3,5712829
When an object has multiple classes, is there a rule for the order in which they're returned? The quick work around for what I'm doing presently might be to simply take the first result
– user5783745
Jan 20 at 21:21
Thanks for showingmethods()- very useful!
– user5783745
Jan 20 at 21:22
add a comment |
When an object has multiple classes, is there a rule for the order in which they're returned? The quick work around for what I'm doing presently might be to simply take the first result
– user5783745
Jan 20 at 21:21
Thanks for showingmethods()- very useful!
– user5783745
Jan 20 at 21:22
When an object has multiple classes, is there a rule for the order in which they're returned? The quick work around for what I'm doing presently might be to simply take the first result
– user5783745
Jan 20 at 21:21
When an object has multiple classes, is there a rule for the order in which they're returned? The quick work around for what I'm doing presently might be to simply take the first result
– user5783745
Jan 20 at 21:21
Thanks for showing
methods() - very useful!– user5783745
Jan 20 at 21:22
Thanks for showing
methods() - very useful!– user5783745
Jan 20 at 21:22
add a comment |
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Albeit a different class, a
data.tablehas 2 classes, the answer from here might help to explain why: stackoverflow.com/a/15986236/2449656– Khaynes
Jan 20 at 7:11
1
Also, see 13.6 from here: adv-r.hadley.nz/s3.html
– Khaynes
Jan 20 at 7:16