[R] "Missing value representation in Excel before extraction to R with RODBC"

[Prof Brian Ripley]

On Mon, 9 Jan 2006, Petr Pikal wrote:

> Hi
>
> I believe it has something to do with the column identification
> decision. When R decides what is in a column it uses only some values
> from the beginning of a file.

Not R, Excel.  Excel tells ODBC what the column types are.

> I do not use RODBC as read.delim("clipboard", ...) is usually more
> convenient but probably there is a way how to tell RODBC what is in
> the column instead of let R decide from the top of the file.

Using as.is=TRUE stops RODBC doing any conversion.

> But I may be completely mistaken.
>
> HTH
> Petr
>
>
> On 6 Jan 2006 at 20:47, Fredrik Lundgren wrote:
>
> From:           	"Fredrik Lundgren" <fredrik.bg.lundgren at bredband.net>
> To:             	"R-help" <r-help at stat.math.ethz.ch>
> Date sent:      	Fri, 6 Jan 2006 20:47:29 +0100
> Subject:        	[R] "Missing value representation in Excel before extraction to R
> 	with RODBC"
>
>> Dear list,
>>
>> How should missing values be expressed in Excel before extraction to R
>> via RODBC. I'm bewildered. Sometimes the representation with NA in
>> Excel appears to work and shows up in R as <NA> but sometimes the use
>> of NA in Excel changes the whole vector to NA's. Blank or nothing or
>> NA as representation for missing values in Excel with dateformat gives
>> NA's of the whole vector in R but with  general format in Excel gives
>> blanks for missing values in R. How should I represent missing values
>> in Excel?
>>
>>
>> Best wishes and thanks for any help
>> Fredrik Lundgren

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595