[R] Specifying data type when creating a dataframe using RODBC

J Dougherty jwd at surewest.net
Thu May 14 04:50:33 CEST 2009

On Tuesday 12 May 2009 02:59:30 pm Mark Na wrote:
> H R-helpers,
> One column (several, actually) in the spreadsheet contains integers in
> its first few rows but later values in these columns contain a mixture
> of numbers, letters and symbols (it's an ID variable, containing e.g.,
> 12, 14, 19, 19B, 19C, 19/20)
> R creates this column as a numeric variable (I think because its first
> few variables are numbers) but as soon as R gets to the non-numeric
> values (e.g., 19/20) it replaces them with NA.

This is much more likely to be an Excel issue, and if the data is important at 
all you would be better off keeping in Access.  Excel has several automatic 
features that can result in damaged data.  See the article by B.D.McCullough 
and David A. Heiser in Computational Statistics and Data Analysis 52(2008) 

> So, my question is: how can I specify that certain columns are to be
> read as character variables BEFORE the dataframe is created?
> I have tried using as.character() in the third line (above) but it
> creates a very long first column containing all of my data...
> Thanks for any help you might provide,
> Mark Na
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