Re: [R] xmat[1, 2:3] <- NULL

From: Mikkel Grum <mi2kelgrum_at_yahoo.com>
Date: Fri 08 Jul 2005 - 18:38:33 EST


Thanks for this! This is even simpler than using !is.null():

xmat <- as.data.frame(matrix(NA, 2, 3))
try(xmat[i, 2:3] <- dbGetQuery(...), silent = TRUE)

Best wishes,
Mikkel

> Mikkel Grum wrote:
>
> > I have a situation where I'm filling out a
> dataframe
> > from a database. Sometimes the database query
> doesn't
> > get anything, so I end up trying to place NULL in
> the
> > dataframe like below.
> >
> >
> >>temp <- NULL
> >>xmat <- as.data.frame(matrix(NA, 2, 3))
> >>xmat[1, 2:3] <- temp
> >
> > Error in if (m < n * p && (n * p)%%m)
> > stop(gettextf("replacement has %d items, need %d",
> :
> > missing value where TRUE/FALSE needed
> >
> > I can't get the programme to accept that sometimes
> > what the query looks for just doesn't exist, and I
> > just want to move on to the next calculation
> leaving
> > the dataframe with a missing value in the given
> cell.
> > It's a real show stopper and I haven't found a way
> > round it.
>
>
> See ?try
>
> Uwe Ligges
>
>
> > Best wishes,
> > Mikkel
> >
> > PS. I'm using dbGetQuery to query an SQLite
> database.
> >
> > ______________________________________________
> > R-help@stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>
>



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 08 18:49:02 2005

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