[R-SIG-Finance] Importing from Excel

[Spencer Graves]

      I've had good luck with 'read.xls{gdata}', but that could have the 
same problem. 

      If this still gives you problems, you could put your favorite 
'read.*(...)' in a function that tests columns you specify to see if 
they are numeric and if not tries to replace them with

           is.numeric(as.character(DF[[i]]))

      for column i of data.frame DF.  You could test that to see what 
percent NAs you have and write a warning, etc., whatever you want. 

      hope this helps. 
      Spencer

MAB wrote:
> Hi!
>
> I am trying to diff data imported from Excel.
> I use the package xlsReadWrite.
>
> After I load the following XL spreadsheet
>
> C_Dates C_Price C_Prices_edit         C_Return_Raw        C_Return_edit
> 1   30405   29.40         29.40                 #N/A                 #N/A
> 2   30406   29.29         NaN                 -0.003               -0.003
> 3   30407      NA         29.29                    0                    0
> (#N/A is a string in one case and the formula =NA() in another)
>
> and try to diff the resulting object, I get:
>
> Error in r[i1, , drop = FALSE] - r[-nrow(r):-(nrow(r) - lag + 1), , drop = 
> FALSE] : 
>         non-numeric argument to binary operator
>
> I attempt to convert to numeric using as.matrix (or data.matrix),
> but this converts the object to all characters.
>
> I can then use as.numeric to get a vector and rebuild the matrix but this gets 
> tedious.
>
> Eventually the easiest seems to be to make sure each column in the spreadsheet
> starts with a numeric, and replace it once the object is in R.
>
> There is probably a better way.
>
> Michel
>
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