R help - Aug 2010 - modifying factors in a data frame

Hi All

I have a data frame in which on the columns is a factor with following
levels

Levels: M006 M0114 M0379 M0432 M0823 M1012 M1096 M1107 SW393 SW708

I want to change all the M006 to "1", M0114 to "2" and so
on.  What I am
trying is not working.

data1$sample[data1$sample =='M006'] <- "1"
Warning message:
In `[<-.factor`(`*tmp*`, data1$sample == "M006", value =
"1") :
  invalid factor level, NAs generated


Any slick way to do this ?

Thanks!
-Abhi

	[[alternative HTML version deleted]]

Tena koe Abhi

The easiest way is probably

data1$sample <- as.numeric(data1$sample)

If you want it to remain as a factor then

data1$sample <- as.factor(as.numeric(data1$sample))

HTH ....

Peter Alspach
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Abhishek Pratap
> Sent: Thursday, 19 August 2010 5:41 p.m.
> To: r-help at r-project.org
> Subject: [R] modifying factors in a data frame
> 
> Hi All
> 
> I have a data frame in which on the columns is a factor with following
> levels
> 
> Levels: M006 M0114 M0379 M0432 M0823 M1012 M1096 M1107 SW393 SW708
> 
> I want to change all the M006 to "1", M0114 to "2" and
so on.  What I
> am
> trying is not working.
> 
> data1$sample[data1$sample =='M006'] <- "1"
> Warning message:
> In `[<-.factor`(`*tmp*`, data1$sample == "M006", value =
"1") :
>   invalid factor level, NAs generated
> 
> 
> Any slick way to do this ?
> 
> Thanks!
> -Abhi
> 
> 	[[alternative HTML version deleted]]
> 
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