[R] RODBC connection - mixed data types

[Prof Brian D Ripley]

On Tue, 14 Aug 2001, Petr Pikal wrote:

> Dear R users
>
> I use R (1.3.0) Windows version usually with connection to Excel
> sheets via RODBC Version: 0.8-2. Everything is OK until I use mixed
> data types (numeric and character) in one column.

You can't have different data types in one column of a data frame. You are
not telling us what you are doing (at all: not a single command you used),
but I suspect you need to know about as="matrix", which will import the
data as a character matrix for you.

> In that case I will get a particular column of data frame with NA's.
>
> Example
>
> vzorek   	lpas  	apas
> NA 	51.240 	20.26
> NA 	51.340 	20.42
> NA 	49.770 	22.05
> RB 12 	49.840 	19.30
> RB 12 	49.880 	19.32
>
> But in actual Excel sheet instead of NA values were numbers 11
> (numeric). I can modify elevens in Excel as let say RB 11 or
> something like that, but if there are more such columns and many
> different values it can be quite complicated.
>
> The values are either considered character, converted to factor and
> numeric values are changed to NA or numeric and character values
> are converted to NA.
>
> > is.factor(pigment[,1])
> [1] TRUE
> > is.numeric(pigment[,2])
> [1] TRUE
> > is.numeric(pigment[,3])
> [1] TRUE
>
> I tried parameter as.is but it did not help and I did not find any clue
> other then I(....) but I can not resolve how to use it in that case.
>
> Is there any possibility how to handle different data types in one Excel
> sheet column directly by using ODBC connection and keep all values
> in such column as they are when moving data from Excel to R?

Not as such.  Bu you can get them all as characters strings.

>
> Thank you.
> Petr Pikal
> Precheza a.s.
> Nabr.Dr.E.Benese 24
> tel: 00420 641 25 2257
>      +420 (0)724 008 364
>      petr.pikal at precheza.cz
>      p.pik at volny.cz
>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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