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

[Uwe Ligges]

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.
> 
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