Re: [R] Changing zeros to NAs in a data frame

2004-11-16 Thread Sundar Dorai-Raj 

Laura Holt wrote:
Dear R People:
I have a data frame with some columns that are numeric and some which 
are factors.

There are zeros in the numeric columns and I would like to change them 
to NAs.  However, there are zeros in some of the factor columns, and I 
would like them to be left alone.

Is there a global way to do this, please?  I was thinking about use 
the results from str but am not sure.

R Version 2.0.0 Windows.
Let x be your data.frame. Then use:
is.num - sapply(x, is.numeric)
x[is.num] - lapply(x[is.num], function(y) ifelse(y == 0, NA, y))
HTH,
--sundar
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RE: [R] Changing zeros to NAs in a data frame

2004-11-16 Thread Andy Bunn 
This isn't pretty but it's a way to do it:

foo - data.frame(x = c(1,0,1,1,0,2,4), y = as.factor(c(0,2,1,1,0,3,1)))
Zero2NA - function(x){
if(is.numeric(x)) { x[x == 0] - NA; }
return(x)
}
foo2 - as.data.frame(lapply(foo, Zero2NA))
foo
foo2

HTH, Andy


 -Original Message-
 From: [EMAIL PROTECTED]
 [mailto:[EMAIL PROTECTED] Behalf Of Laura Holt
 Sent: Tuesday, November 16, 2004 11:31 AM
 To: [EMAIL PROTECTED]
 Subject: [R] Changing zeros to NAs in a data frame


 Dear R People:

 I have a data frame with some columns that are numeric and some which are
 factors.

 There are zeros in the numeric columns and I would like to change them to
 NAs.  However, there are zeros in some of the factor columns, and I would
 like them to be left alone.

 Is there a global way to do this, please?  I was thinking about use the
 results from str but am not sure.

 R Version 2.0.0 Windows.

 Thanks in advance.
 Sincerely,
 Laura Holt
 mailto: [EMAIL PROTECTED]


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Re: [R] Changing zeros to NAs in a data frame

2004-11-16 Thread Prof Brian Ripley 
On Tue, 16 Nov 2004, Laura Holt wrote:
Dear R People:
I have a data frame with some columns that are numeric and some which are 
factors.

There are zeros in the numeric columns and I would like to change them to 
NAs.  However, there are zeros in some of the factor columns, and I would 
like them to be left alone.

Is there a global way to do this, please?  I was thinking about use the 
results from str but am not sure.
myDF - data.frame(a=0:4, b=letters[1:5], c=-2:2)
myDF[] - lapply(myDF, function(x) if(is.numeric(x)) {x[x==0] - NA; x} else x)
myDF
   a b  c
1 NA a -2
2  1 b -1
3  2 c NA
4  3 d  1
5  4 e  2
--
Brian D. Ripley,  [EMAIL PROTECTED]
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel:  +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UKFax:  +44 1865 272595
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