[R] Problem with data type recognition and conversion

[Petr Pikal]

Hi

On 31 Oct 2006 at 22:42, tom soyer wrote:

Date sent:      	Tue, 31 Oct 2006 22:42:40 -0600
From:           	"tom soyer" <tom.soyer at gmail.com>
To:             	r-help <r-help at stat.math.ethz.ch>
Subject:        	[R] Problem with data type recognition and conversion

> Hi,
> 
> I have a CSV file with two columns; the first column is date, second
> column is numbers. I used read.csv() to load the file into the
> variable temp. Somehow, R could not recognize my numbers as double.
> Instead, it thinks these numbers are integer even though they all have
> decimal points (isn't that strange?). The problem I ran into is that
> if I tried to convert the numbers to double using as.double, R doesn't
> give me the original value; e.g. 9.92 becomes 805 (see below).
> 
> > temp[1,2]
> [1] 9.92
> 812 Levels:     . 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07
> 10.08 10.09 10.10 10.11 10.12 ... 9.99 > typeof(temp[1,2]) [1]
> "integer" > as.double(temp[1,2]) [1] 805
Levels always tell you it is a factor. Your csv file has an extra 
decimal point or something odd that forces R to convert second column 
to factor. You can transfer factor variable to numeric one by 

as.numeric(as.character(temp[,2]))

however I recommend you to go through your csv file (if it is not too 
big) and find the problematic item.

> 
> If I leave the numbers as integer, then I can't do arithmetic
> operations on them. Does anyone know what's going on?

see ?factor

HTH
Petr
> 
> Thanks,
> 
> Tom
> 
>  [[alternative HTML version deleted]]
> 
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Petr Pikal
petr.pikal at precheza.cz