[R] RODBC and Excel: Wrong Data Type Assumed on Import

[Petr Pikal]

Hi

As I now exclusively use copy paste method to transfer data from 
Excel to R I tried it and I got correctly a factor column when there 
were some non numeric data in Excel.

Ctrl-C in Excel
mydf<-read.delim("clipboard") in R


Are you sure that a respective column in Excel has values 275a and 
275b in it? 

If yes I had tried to define colClasses vector for your columns.

HTH
Petr


On 2 Nov 2005 at 12:45, Earl F. Glynn wrote:

To:             	r-help at stat.math.ethz.ch
From:           	"Earl F. Glynn" <efg at stowers-institute.org>
Date sent:      	Wed, 2 Nov 2005 12:45:53 -0600
Subject:        	[R] RODBC and Excel:  Wrong Data Type Assumed on Import

> The first column in my Excel sheet has mostly numbers but I need to
> treat it as character data:
> 
> > library(RODBC)
> > channel <- odbcConnectExcel("U:/efg/lab/R/Plasmid/construct
> > list.xls") plasmid <- sqlFetch(channel,"Sheet1", as.is=TRUE)
> > odbcClose(channel)
> 
> > names(plasmid)
> [1] "Plasmid Number" "Plasmid"        "Concentration"  "Comments"
> "Lost"
> 
> # How is the type decided?  I need a character type.
> > class(plasmid$"Plasmid Number")
> [1] "numeric"
> > typeof(plasmid$"Plasmid Number")
> [1] "double"
> 
> > plasmid$"Plasmid Number"[273:276]
> [1] 274  NA  NA 276
> 
> The two NAs are supposed to be 275a and 275b.  I tried the
> "as.is=TRUE" but that didn't help.
> 
> I consulted Section 4, Relational databases, in the R Data
> Import/Export document (for Version 2.2.0).
> 
> Section 4.2.2, Data types, was not helpful.  In particular, this did
> not seem helpful:  "The more comprehensive of the R interface packages
> hide the type conversion issues from the user."
> 
> Section 4.3.2, Package RODBC, provided a "simple example of using ODBC
> .. with a(sic) Excel spreadsheet" but is silent on how to control the
> data type on import.  Could the documentation be expanded to address
> this issue?
> 
> I really need to show "Plasmid 275a" and "Plasmid 275b" instead of
> "Plasmid NA".
> 
> Thanks for any help with this.
> 
> efg
> --
> Earl F. Glynn
> Scientific Programmer
> Bioinformatics Department
> Stowers Institute for Medical Research
> 
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Petr Pikal
petr.pikal at precheza.cz