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grep

6 messages · Steven Yen, David Winsemius, Jeff Newmiller +1 more

#
Below, the first command simply creates a list of 16 names (labels) 
which can be ignore.

In the 2nd and 3rd commands, I am able to identify names containing "black".

In line 4, I am trying to identify names containing "black" or "conserv" 
but obviously it does not work. Can someone help? Thanks.

 > names<-names(tp.nohs$estimate)[c(1:8,58:65)]; names
 ?[1] "x1.one"????? "x1.black"??? "x1.othrrace" "x1.moddkna" 
"x1.conserv"? "x1.nstrprty"
 ?[7] "x1.strrep"?? "x1.sevngprt" "x2.one"????? "x2.black" "x2.othrrace" 
"x2.moddkna"
[13] "x2.conserv"? "x2.nstrprty" "x2.strrep"?? "x2.sevngprt"
 > grep("black",names,value=TRUE)
[1] "x1.black" "x2.black"
 > grep("black",names,value=FALSE)
[1]? 2 10
 > grep(c("black","conserv"),names,value=TRUE)
[1] "x1.black" "x2.black"
Warning message:
In grep(c("black", "conserv"), names, value = TRUE) :
 ? argument 'pattern' has length > 1 and only the first element will be used
#
On 5/8/21 10:00 AM, Steven Yen wrote:
Try using the logical OR operator (vertical bar, AKA "pipe")

grep(c("black|conserv"), names, value=TRUE)
#
Regular expression patterns are not vectorized... only the data to be searched are. Use one of the many websites dedicated to tutoring regular expressions to learn how they work. (Using function names like "names" as data names is bad practice.)

nms <- c( "x1.one", "x1.black", "x1.othrrace", "x1.moddkna", "x1.conserv", "x1.nstrprty", "x1.strrep", "x1.sevngprt", "x2.one", "x2.black", "x2.othrrace", "x2.moddkna", "x2.conserv", "x2.nstrprty", "x2.strrep", "x2.sevngprt" )

grep( "black|conserv", nms, value = TRUE )
On May 8, 2021 10:00:12 AM PDT, Steven Yen <styen at ntu.edu.tw> wrote:

  
    
#
Hello,

The pattern can be assembled with paste(., collapse = "|").
With the same vector of names, nms:


words <- c("black","conserv")
pattern <- paste(words, collapse = "|")
grep(pattern = pattern, nms, value = TRUE)
#[1] "x1.black"   "x1.conserv" "x2.black"   "x2.conserv"


Hope this helps,

Rui Barradas

?s 18:20 de 08/05/21, Jeff Newmiller escreveu:
#
Thank to Rui, Jeff, and Bert. They are all very useful.
Somewhat related is the following, in which jindex is a numeric or 
alphanumeric vector in a function that starts with

try<-function(...., jindex=NA)

In the if loop, in the first line I am trying to determine whether the 
vector jindex is NA;
In the second line, I am trying to determine whether elements in vector 
jindex is are all non-numeric.

Not sure how so I tried to judge by the first element of jindex. Any 
better way? Thannks.

 ? if (!is.na(jindex[1])){?????? # like to improve this line
 ??? if(!is.numeric(jindex)[1]){ # like to improve this line
 ????? words? <-jindex
 ????? pattern<-paste(words,collapse="|")
 ????? jindex <-grep(pattern=pattern,x.label,value=FALSE)
 ??? }
 ??? jj<-jindex; x.label<-x.label[jj]
 ? }
On 2021/5/9 ?? 03:02, Rui Barradas wrote:
#
Hello,

Maybe instead of a loop, vectorize with logical indices.


i1 <- is.na(jindex)
i2 <- is.numeric(jindex)
if(any(!i1)){
   if(any(!i2)){
     words <- jindex[!i1 & !i2]
     pattern <- paste(words, collapse = "|")
     jindex <- grep(pattern = pattern, x.label, value = FALSE)
   }
   jj <- jindex[!i1]
   x.label <- x.label[jj]
}


Or even simpler

if(any(!i1 & !i2)){
   words <- jindex[!i1 & !i2]
   pattern <- paste(words, collapse = "|")
   jindex <- grep(pattern = pattern, x.label, value = FALSE)
   jj <- jindex[!i1]
   x.label <- x.label[jj]
}


Hope this helps,

Rui Barradas

?s 02:54 de 09/05/21, Steven Yen escreveu: