Is it true that this is a vector?
c(1)
Yes,
because c(1) is a collection of integer values of length one.
Is it true that this is a vector?
c(1,2,3)
Yes,
because c(1,2,3) is a collection of integer values of length three.
Is it true that this is a vector?
c("cat","dog","mouse")
Yes,
because c("cat","dog","mouse") is a collection of character values.
Is it true that this is a vector?
c(2.3,4.1)
Yes,
because c(2.3,4.1) is a collection of double values.
Is it true that this is a vector?
c(TRUE,TRUE,FALSE)
Yes,
because c(TRUE,TRUE,FALSE) is a collection of logical values.
Is it true that this is a vector?
list(1,"cat",4.1)
Yes,
because list(1,"cat",4.1) is a collection of values of type integer, character and double.
Is it true that this is an atomic vector?
list(1,"cat",4.1)
No,
because list(1,"cat",4.1) is a collection of values of type integer, character and double.
Is it true that this is an atomic vector?
c(1,2,3)
Yes,
because c(1,2,3) is a collection of values of type integer.
Is it true that this is an atomic vector?
c("cat","dog","mouse")
Yes,
because c("cat","dog","mouse") is a collection of values of type character.
Is it true that this is an atomic vector?
c(2.3,4.1)
Yes,
because c(2.3,4.1) is a collection of values of double character.
Is it true that this is a list?
list(1,"cat",4.1)
Yes,
because list(1,"cat",4.1) is a collection of values of type integer, character and double.
Is it true that this is a list?
c(1,"cat",4.1)
No,
because c(1,"cat",4.1) is a collection of values of type character.
Is it true that this is a list?
list(1,"cat",c(2,"dog"))
Yes,
because list(1,"cat",c(2,"dog")) is a collection of values of type integer, character and list.
Is it true that this is a vector?
c(one=1, two=2, three=3)
Yes,
because c(one=1, two=2, three=3) is a collection of named/tagged values.
Is it true that this is a vector?
c(one=1, one=2, one=3)
Yes,
because c(one=1, one=2, one=3) is a collection of named/tagged values.
Is it true that this is a vector?
list(one=1, one=2, one=c(1,2,"smile"))
Yes,
because list(one=1, one=2, one=c(1,2,"smile")) is a collection of named/tagged values.
What is names(w) where w is
list(one=1, two=2, three=c(1,2,"smile"))
"one" "two" "three"
because names(w) is a way of asking for the names of w.
What is w[1] where w is
c(1,2,3)
1
because 1 is the first element of atomic vector w.
What is w[1] where w is
list(1,2,"3")
list(1)
because 1 is a slice of the list w containing the first element.
What is w[[1]] where w is
list(1,2,"3")
1
because 1 is the first element of list w. More precisely, you can say that it's the first element in the slice of list w containing the first element of list w.
What is w[[2]] where w is
list(1,2,"3")
2
because 2 is the second element of list w. More precisely, you can say that it's the first element in the slice of list w containing the second element of list w.
What is w[1] where w is
c(1,2,"3")
"1"
because 1 is the first element of atomic vector w, and atomic vector w contains a value of type character.
What is w[2] where w is
c(1.0,2,3.0)
2.0
because 2 is the first element of atomic vector w, and atomic vector w contains a value of type double.
What is w[1] where w is
c(TRUE,2.0,3)
1.0
because TRUE is the first element of atomic vector w, and atomic vector w contains a value of type double.
What is w[[1]] where w is
list(TRUE,2.0,3)
TRUE
because TRUE is the first element in list w. More precisely, you can say that it's the first element in the slice of list w containing the first element of list w.
What is names(w[[2]]) where w is
list(one=1, two=2, three=c(1,2,"smile"))
"two"
because "two" is the name of the second element of list w.
What is w[c(1,3)] where w is
c("mercury","venus","earth","mars")
"mercury" "earth"
because "mercury" and "earth" are the first and third elements of vector w.
What is w[c(1,1,2,1)] where w is
c("mercury","venus","earth","mars")
"mercury" "mercury" "venus" "mercury"
because "mercury" and "venus" are the first and second elements of vector w.
What is w[4] where w is
c("mercury","venus",c("earth","mars"))
"mars"
because "mars" is the fourth element of atomic vector w.
What is w[4] where w is
list("mercury","venus",c("earth","mars"))
NULL
because the list w does not have four elements.
What is w[[3]][2] where w is
list("mercury","venus",c("earth","mars"))
"mars"
because c("earth","mars")) is the third element of list w and mars is the second element of atomic vector c("earth","mars")).
What is w[2:4] where w is
c("mercury","venus","earth","mars","jupiter","saturn")
"venus" "earth" "mars"
because "venus", "earth" and "mars" are the second through fourth elements of vector w.
What is w$planet_2 where w is
list("planet_1"="mercury","planet_2"="venus","planet_3"="earth")
"venus"
because planet_2 is the name of value "venus" in list w.
What is w$planet_2 where w is
c("planet_1"="mercury","planet_2"="venus","planet_3"="earth")
nothing
because you cannot use the $ syntax to refer to a named element of an atomic vector, only a named element of a list.