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I have a named numeric vector vec, then it was sorted in ascending order and saved in object vec_sort, as shown below.

vec <- c(1,1,1,2,3,1,5)
names(vec) <- letters[1:7]
vec
# a b c d e f g 
# 1 1 1 2 3 1 5 

str(vec)
# Named num [1:7] 1 1 1 2 3 1 5
# - attr(*, "names")= chr [1:7] "a" "b" "c" "d" ...

Sorted in Ascending Order (Named Numeric Vector)

vec_sort <- sort(vec)
vec_sort
# a b c f d e g 
# 1 1 1 1 2 3 5 

str(vec_sort)
# Named num [1:7] 1 1 1 1 2 3 5
# - attr(*, "names")= chr [1:7] "a" "b" "c" "f" ...

OUTPUT REQUIRED

A Named Logical Vector where in First 3 element of ascending order numeric vector to be TRUE, rest FALSE. Even if 4th element is same as first 3 elements. i.e. the lowest value. Using relational operators or by assigning it may be.

vec_sort
# a b c f d e g 
# 1 1 1 1 2 3 5

TO

vec_sort
#    a     b     c     f     d     e     g 
# TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE

Codes Attempted

1st

vec_sort[1:3] <- TRUE
vec_sort[4:length] <- FALSE

vec_sort
# a b c f d e g 
# 1 1 1 0 0 0 0

Not Logical

str(vec_sort)
# Named num [1:7] 1 1 1 0 0 0 0
- attr(*, "names")= chr [1:7] "a" "b" "c" "f" ...

2nd

 vec_sort <= min(vec_sort)
 #    a     b     c     f     d     e     g 
 # TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE

Here 4th variable f also comes up to be TRUE as the condition is set like that. it is minimum, but from minimum also, I want to set only top 3 to TRUE

Many more logical conditions attempted, but it all results in first 4 as TRUE and if I try assigning it to TRUE or FALSE it turns out to be a Named Numeric Vector showing hopefully 1 as TRUE and 0 as FALSE, but not ending up to be a Named Logical Vector.

Sowmya S. Manian
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1 Answers1

4
setNames(as.logical(replace(replace(vec_sort, TRUE, FALSE), 1:3, TRUE)), names(vec_sort))
#OR
setNames(as.logical(replace(vec_sort * 0, 1:3, 1)), names(vec_sort))
#OR
setNames(c(rep(TRUE, 3), rep(FALSE, length(vec_sort)-3)), names(vec_sort))
#OR
replace(vec_sort == max(vec_sort) + 999, 1:3, TRUE)
#   a     b     c     f     d     e     g 
#TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE
d.b
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  • Thanks a lot. It worked well. Tried the first you posted, it was long but worked. Will have to try these. Any way through relational operators? – Sowmya S. Manian Oct 26 '17 at 20:23
  • Could you please also include the 1st version of command that you posted. – Sowmya S. Manian Oct 26 '17 at 20:29
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    My named numeric vector is of length 20000+ and lowest value occurs like 2000 times. So basically with each command that you posted, should not result in loss of names of the vector. All of them works!! Thank you, learning all these functions. Completely slipped my mind `replace( )`. – Sowmya S. Manian Oct 26 '17 at 20:30