if statement and for loop question

Hi Kai,
You seem to be asking the same question again and again. This does not
give us the warm feeling that you know what you want.

testdf<-data.frame(a=c("Negative","Positive","Neutral","Random","VUS"),
 b=c("No","Yes","No","Maybe","Yes"),
 c=c("Off","On","Off","Off","On"),
 d=c("Bad","Good","Bad","Bad","Good"),
 stringsAsFactors=FALSE)
testdf
match_strings<-c("Positive","VUS")
testdf$b<-ifelse(testdf$a %in% match_strings,testdf$b,"")
testdf$c<-ifelse(testdf$a %in% match_strings,testdf$c,"")
testdf$d<-ifelse(testdf$a %in% match_strings,testdf$d,"")
testdf

I have assumed that you mean "zero length strings" rather than
"zeros". Also note that your initial code was producing logical values
that were never assigned to anything.

Jim

On Mon, May 31, 2021 at 2:29 AM Kai Yang via R-help

Hello List,I have a data frame which having the character columns:

| a1 | b1 | c1 | d1 |
| a2 | b2 | c2 | d2 |
| a3 | b3 | c3 | d3 |
| a4 | b4 | c4 | d4 |
| a5 | b5 | c5 | d5 |



I need to do: if a1 not = "Positive" and not = "VUS" then values of  b1, c1 and d1 will be zero out. And do the same thing for the a2 to a5 series.
I write the code below to do this. But it doesn't work. Would you please correct my code?
Thank you,
Kai


for (i in 1:5)
{
  if (isTRUE(try$a[i] != "Positive" && try$a[i] != "VUS"))
  {
    try$b[i]== ''
    try$c[i] == ''
    try$d[i]== ''
  }
}


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