[R] Apply gsub to dataframe to modify row values

Luigi Marongiu
Mon, 09 Aug 2021 10:50:00 -0000

Sorry, silly question, gsub works already with regex. But still, if I
add `[[:blank:]]` still I don't get rid of all instances. And I am
keeping obtaining extra columns
```
> df[df$VAL] = gsub("[[:blank:]Value is]", "", df$VAL,
ignore.case=TRUE)
> df[df$VAL] = gsub("[[:blank:]Value is]", "", df$VAL,
ignore.case=TRUE);df
  VAR           VAL value is blue Value is red empty
1   1 value is blue             b            b     b
2   2  Value is red            rd           rd    rd
3   3         empty          mpty         mpty  mpty
```

On Mon, Aug 9, 2021 at 12:40 PM Luigi Marongiu <marongiu.luigi at
gmail.com> wrote:
>
> Thank you, that is much appreciated. But on the real data, the
> substitution works only on few instances. Is there a way to introduce
> regex into this?
> Cheers
> Luigi
>
> On Mon, Aug 9, 2021 at 11:01 AM Jim Lemon <drjimlemon at gmail.com>
wrote:
> >
> > Hi Luigi,
> > Ah, now I see:
> >
> >  df$VAL<-gsub("Value
is","",df$VAL,ignore.case=TRUE)
> > df
> >  VAR   VAL
> > 1   1  blue
> > 2   2   red
> > 3   3 empty
> >
> > Jim
> >
> > On Mon, Aug 9, 2021 at 6:43 PM Luigi Marongiu <marongiu.luigi at
gmail.com> wrote:
> > >
> > > Hello,
> > > I have a dataframe where I would like to change the string of
certain
> > > rows, essentially I am looking to remove some useless text from
the
> > > variables.
> > > I tried with:
> > > ```
> > > > df = data.frame(VAR = 1:3, VAL = c("value is
blue", "Value is red", "empty"))
> > > > df[df$VAL] = gsub("value is ", "",
df$VAL, ignore.case = TRUE, perl = FALSE)
> > > > df
> > >   VAR           VAL value is blue Value is red empty
> > > 1   1 value is blue          blue         blue  blue
> > > 2   2  Value is red           red          red   red
> > > 3   3         empty         empty        empty empty
> > > ```
> > > which is of course wrong because I was expecting
> > > ```
> > >   VAR           VAL
> > > 1   1             blue
> > > 2   2             red
> > > 3   3            empty
> > > ```
> > > What is the correct syntax in these cases?
> > > Thank you
> > >
> > > ______________________________________________
> > > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more,
see
> > > 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.
>
>
>
> --
> Best regards,
> Luigi



--
Best regards,
Luigi