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Liviu Andronic

2012-Jul-30 15:53 UTC

[R] replace values in vector from a replacement table

Dear all
I've got stuck when trying to replace values in a vector by selecting
replacements from a replacement table. I'm trying to use only base
functions. Here's a dummy example:> (x <- rep(letters,2)) [1] "a" "b" "c" "d" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
"q" "r" "s" "t" "u"
"v"
[23] "w" "x" "y" "z" "a"
"b" "c" "d" "e" "f"
"g" "h" "i" "j" "k"
"l"
"m" "n" "o" "p" "q"
"r"
[45] "s" "t" "u" "v" "w"
"x" "y" "z"> values <- c("aa", "a", "b", NA,
"d", "zz")
> repl <- c("aa", "A", "B", NA,
"D", "zz")
> (repl.tab <- cbind(values, repl))     values repl
[1,] "aa"   "aa"
[2,] "a"    "A"
[3,] "b"    "B"
[4,] NA     NA
[5,] "d"    "D"
[6,] "zz"   "zz"


Now I can easily compute all four combinations of 'match' and
'%in%':> (ind <- match(x, repl.tab[ ,1])) [1]  2  3 NA  5 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
NA NA NA NA  2  3 NA
[30]  5 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
NA> (ind <- match(repl.tab[ ,1], x))
[1] NA  1  2 NA  4 NA> (ind <- x %in% repl.tab[ ,1]) [1]  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
FALSE FALSE FALSE
[15] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
FALSE  TRUE  TRUE
[29] FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
FALSE FALSE FALSE
[43] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
FALSE> (ind <- repl.tab[ ,1] %in% x)[1] FALSE  TRUE  TRUE FALSE  TRUE FALSE


But how do I actually proceed to obtain the following vector?  Can it
be done without an explicit apply() or loop?> res [1] "A" "B" "c" "D" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
"q" "r" "s" "t" "u"
"v"
[23] "w" "x" "y" "z" "A"
"B" "c" "D" "e" "f"
"g" "h" "i" "j" "k"
"l"
"m" "n" "o" "p" "q"
"r"
[45] "s" "t" "u" "v" "w"
"x" "y" "z"


Regards
Liviu


-- 
Do you know how to read?
http://www.alienetworks.com/srtest.cfm
http://goodies.xfce.org/projects/applications/xfce4-dict#speed-reader
Do you know how to write?
http://garbl.home.comcast.net/~garbl/stylemanual/e.htm#e-mail

jim holtman

2012-Jul-30 16:00 UTC

head link

[R] replace values in vector from a replacement table

try this:
> (x <- rep(letters,2)) [1] "a" "b" "c" "d" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
"q" "r" "s" "t" "u"
"v" "w"
[24] "x" "y" "z" "a" "b"
"c" "d" "e" "f" "g"
"h" "i" "j" "k" "l"
"m"
"n" "o" "p" "q" "r"
"s" "t"
[47] "u" "v" "w" "x" "y"
"z"> values <- c("aa", "a", "b", NA,
"d", "zz")
> repl <- c("aa", "A", "B", NA,
"D", "zz")
> (repl.tab <- cbind(values, repl))     values repl
[1,] "aa"   "aa"
[2,] "a"    "A"
[3,] "b"    "B"
[4,] NA     NA
[5,] "d"    "D"
[6,] "zz"   "zz"> indx <- match(x, repl.tab[, 1], nomatch = 0)
> x[indx != 0] <- repl.tab[indx, 2]
> x [1] "A" "B" "c" "D" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
"q" "r" "s" "t" "u"
"v" "w"
[24] "x" "y" "z" "A" "B"
"c" "D" "e" "f" "g"
"h" "i" "j" "k" "l"
"m"
"n" "o" "p" "q" "r"
"s" "t"
[47] "u" "v" "w" "x" "y"
"z">
>

On Mon, Jul 30, 2012 at 11:53 AM, Liviu Andronic <landronimirc at
gmail.com> wrote:> Dear all
> I've got stuck when trying to replace values in a vector by selecting
> replacements from a replacement table. I'm trying to use only base
> functions. Here's a dummy example:
>> (x <- rep(letters,2))
>  [1] "a" "b" "c" "d" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
> "q" "r" "s" "t" "u"
"v"
> [23] "w" "x" "y" "z" "a"
"b" "c" "d" "e" "f"
"g" "h" "i" "j" "k"
"l"
> "m" "n" "o" "p" "q"
"r"
> [45] "s" "t" "u" "v" "w"
"x" "y" "z"
>> values <- c("aa", "a", "b", NA,
"d", "zz")
>> repl <- c("aa", "A", "B", NA,
"D", "zz")
>> (repl.tab <- cbind(values, repl))
>      values repl
> [1,] "aa"   "aa"
> [2,] "a"    "A"
> [3,] "b"    "B"
> [4,] NA     NA
> [5,] "d"    "D"
> [6,] "zz"   "zz"
>
>
> Now I can easily compute all four combinations of 'match' and
'%in%':
>> (ind <- match(x, repl.tab[ ,1]))
>  [1]  2  3 NA  5 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
> NA NA NA NA  2  3 NA
> [30]  5 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
>> (ind <- match(repl.tab[ ,1], x))
> [1] NA  1  2 NA  4 NA
>> (ind <- x %in% repl.tab[ ,1])
>  [1]  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> FALSE FALSE FALSE
> [15] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> FALSE  TRUE  TRUE
> [29] FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> FALSE FALSE FALSE
> [43] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
>> (ind <- repl.tab[ ,1] %in% x)
> [1] FALSE  TRUE  TRUE FALSE  TRUE FALSE
>
>
> But how do I actually proceed to obtain the following vector?  Can it
> be done without an explicit apply() or loop?
>> res
>  [1] "A" "B" "c" "D" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
> "q" "r" "s" "t" "u"
"v"
> [23] "w" "x" "y" "z" "A"
"B" "c" "D" "e" "f"
"g" "h" "i" "j" "k"
"l"
> "m" "n" "o" "p" "q"
"r"
> [45] "s" "t" "u" "v" "w"
"x" "y" "z"
>
>
> Regards
> Liviu
>
>
> --
> Do you know how to read?
> http://www.alienetworks.com/srtest.cfm
> http://goodies.xfce.org/projects/applications/xfce4-dict#speed-reader
> Do you know how to write?
> http://garbl.home.comcast.net/~garbl/stylemanual/e.htm#e-mail
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

Liviu Andronic

2012-Jul-30 16:29 UTC

head link

[R] replace values in vector from a replacement table

On Mon, Jul 30, 2012 at 6:00 PM, jim holtman <jholtman at gmail.com>
wrote:> try this:
>> indx <- match(x, repl.tab[, 1], nomatch = 0)
>> x[indx != 0] <- repl.tab[indx, 2]
>> x
>  [1] "A" "B" "c" "D" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
> "q" "r" "s" "t" "u"
"v" "w"
> [24] "x" "y" "z" "A" "B"
"c" "D" "e" "f" "g"
"h" "i" "j" "k" "l"
"m"
> "n" "o" "p" "q" "r"
"s" "t"
> [47] "u" "v" "w" "x" "y"
"z"
>>
>This is excellent!

Thank you
Liviu

Liviu Andronic

2012-Jul-31 10:44 UTC

head link

[R] replace values in vector from a replacement table

On Mon, Jul 30, 2012 at 6:00 PM, jim holtman <jholtman at gmail.com>
wrote:> try this:
>
>> (x <- rep(letters,2))
>  [1] "a" "b" "c" "d" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
> "q" "r" "s" "t" "u"
"v" "w"
> [24] "x" "y" "z" "a" "b"
"c" "d" "e" "f" "g"
"h" "i" "j" "k" "l"
"m"
> "n" "o" "p" "q" "r"
"s" "t"
> [47] "u" "v" "w" "x" "y"
"z"
>> values <- c("aa", "a", "b", NA,
"d", "zz")
>> repl <- c("aa", "A", "B", NA,
"D", "zz")
>> (repl.tab <- cbind(values, repl))
>      values repl
> [1,] "aa"   "aa"
> [2,] "a"    "A"
> [3,] "b"    "B"
> [4,] NA     NA
> [5,] "d"    "D"
> [6,] "zz"   "zz"
>> indx <- match(x, repl.tab[, 1], nomatch = 0)
>> x[indx != 0] <- repl.tab[indx, 2]
>> x
>  [1] "A" "B" "c" "D" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
> "q" "r" "s" "t" "u"
"v" "w"
> [24] "x" "y" "z" "A" "B"
"c" "D" "e" "f" "g"
"h" "i" "j" "k" "l"
"m"
> "n" "o" "p" "q" "r"
"s" "t"
> [47] "u" "v" "w" "x" "y"
"z"
>>
>
Based on this code I came up with the following function.

replace2 <- function(x, ind, repl){
    if(any(is.na(ind))) ind[is.na(ind)] <- 0
    if(is.vector(x) & is.vector(repl)) {
        (x[ind != 0] <- repl[ind])
        return(x)
    } else if(identical(ncol(x), ncol(repl))){
        (x[ind != 0, ] <- repl[ind, ])
        return(x)
    }
}

Whereas replicate() can be used only on vectors of same dimension,
replicate2() can be used on vectors and matrices/dataframes, and the
replacement data can have different nr of rows.  It also works with
index vectors containing NAs.
> ##for vectors
> (indx <- match(x, repl.tab[, 1], nomatch = 0)) [1] 2 3 0 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 3 0 5 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
[46] 0 0 0 0 0 0 0> head(replace2(x, indx, repl.tab[, 2]))[1] "A" "B" "c" "D" "e"
"f"> (indx <- match(x, repl.tab[, 1])) ##index vector with NAs [1]  2  3 NA  5 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
NA NA NA NA  2  3 NA  5
[31] NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
NA> head(replace2(x, indx, repl.tab[, 2]))[1] "A" "B" "c" "D" "e"
"f"> ##for matrices/dataframes
> head(xx <- cbind(x, x))     x   x
[1,] "a" "a"
[2,] "b" "b"
[3,] "c" "c"
[4,] "d" "d"
[5,] "e" "e"
[6,] "f" "f"> (repl.tab2 <- cbind(repl.tab[, 2], repl.tab[, 2]))     [,1] [,2]
[1,] "aa" "aa"
[2,] "A"  "A"
[3,] "B"  "B"
[4,] NA   NA
[5,] "D"  "D"
[6,] "zz" "zz"> head(replace2(xx, indx, repl.tab2))     x   x
[1,] "A" "A"
[2,] "B" "B"
[3,] "c" "c"
[4,] "D" "D"
[5,] "e" "e"
[6,] "f" "f"


Does this function have any generic value? Are there obvious
implementation mistakes?

Regards
Liviu

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