Re: [R] field index given name.

2009-10-12 Thread Schalk Heunis 
Hi Phil
Try the following
 which(names(iris)=='Species')
[1] 5

HTH
Schalk Heunis

On Mon, Oct 12, 2009 at 8:53 AM, tdm ph...@philbrierley.com wrote:


 Hi,

 How do I access the index number of a field given I only know the field
 name?

 eg - I want to set the probability of the field 'species' higher than the
 other fields to use in sampling.

  colprob - array(dim=NCOL(iris))
  for(i in 1:NCOL(iris)){colprob[i]=0.5}
  colprob[iris$species] = 1 #this doesn't work
  colprob
 [1] 0.5 0.5 0.5 0.5 0.5





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Re: [R] field index given name.

2009-10-12 Thread tdm 

Thanks - would never have guessed that. I eventually got the following to do
what I want...

 colprob - array(dim=NCOL(iris))
 for(i in 1:NCOL(iris)){
+ colprob[i]=
+ ifelse(names(iris)[i] == 'Species',1,0.5)
+ }
 colprob
[1] 0.5 0.5 0.5 0.5 1.0




Schalk Heunis-2 wrote:
 
 Hi Phil
 Try the following
 which(names(iris)=='Species')
 [1] 5
 
 HTH
 Schalk Heunis
 
 On Mon, Oct 12, 2009 at 8:53 AM, tdm ph...@philbrierley.com wrote:
 

 Hi,

 How do I access the index number of a field given I only know the field
 name?

 eg - I want to set the probability of the field 'species' higher than the
 other fields to use in sampling.

  colprob - array(dim=NCOL(iris))
  for(i in 1:NCOL(iris)){colprob[i]=0.5}
  colprob[iris$species] = 1 #this doesn't work
  colprob
 [1] 0.5 0.5 0.5 0.5 0.5





 --
 View this message in context:
 http://www.nabble.com/field-index-given-name.-tp25851216p25851216.html
 Sent from the R help mailing list archive at Nabble.com.

 __
 R-help@r-project.org mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide
 http://www.R-project.org/posting-guide.html
 and provide commented, minimal, self-contained, reproducible code.

 
   [[alternative HTML version deleted]]
 
 __
 R-help@r-project.org mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide
 http://www.R-project.org/posting-guide.html
 and provide commented, minimal, self-contained, reproducible code.
 
 

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Re: [R] field index given name.

2009-10-12 Thread David Winsemius 


On Oct 12, 2009, at 3:22 AM, tdm wrote:



Thanks - would never have guessed that. I eventually got the  
following to do

what I want...


colprob - array(dim=NCOL(iris))
for(i in 1:NCOL(iris)){

+ colprob[i]=
+ ifelse(names(iris)[i] == 'Species',1,0.5)
+ }

colprob

[1] 0.5 0.5 0.5 0.5 1.0




This would be more in keeping with the approah in R of avoiding loops  
when possble:


 colprob - array(dim=NCOL(iris))
 colprob[] - 0.5
 colprob
[1] 0.5 0.5 0.5 0.5 0.5
 colprob[names(iris) == Species] - 1
 colprob
[1] 0.5 0.5 0.5 0.5 1.0


--
David



Schalk Heunis-2 wrote:


Hi Phil
Try the following

which(names(iris)=='Species')

[1] 5

HTH
Schalk Heunis

On Mon, Oct 12, 2009 at 8:53 AM, tdm ph...@philbrierley.com wrote:



Hi,

How do I access the index number of a field given I only know the  
field

name?

eg - I want to set the probability of the field 'species' higher  
than the

other fields to use in sampling.


colprob - array(dim=NCOL(iris))
for(i in 1:NCOL(iris)){colprob[i]=0.5}
colprob[iris$species] = 1 #this doesn't work
colprob

[1] 0.5 0.5 0.5 0.5 0.5





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View this message in context:
http://www.nabble.com/field-index-given-name.-tp25851216p25851216.html
Sent from the R help mailing list archive at Nabble.com.

__
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http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.



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David Winsemius, MD
Heritage Laboratories
West Hartford, CT

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Re: [R] field index given name.

2009-10-12 Thread William Dunlap 
 -Original Message-
 From: r-help-boun...@r-project.org 
 [mailto:r-help-boun...@r-project.org] On Behalf Of tdm
 Sent: Monday, October 12, 2009 12:22 AM
 To: r-help@r-project.org
 Subject: Re: [R] field index given name.
 
 
 Thanks - would never have guessed that. I eventually got the 
 following to do
 what I want...
 
  colprob - array(dim=NCOL(iris))
  for(i in 1:NCOL(iris)){
 + colprob[i]=
 + ifelse(names(iris)[i] == 'Species',1,0.5)
 + }
  colprob
 [1] 0.5 0.5 0.5 0.5 1.0

I think a more direct way to do what that does
is to make vector with names, where the names
are the column names of 'iris' and then subscript
the vector by name instead of by number.   E.g.,

colprob - rep(0.5, length=ncol(iris)) # initialize probs
names(colprob) - colnames(iris) # initialize names
colprob[Species] - 1.0  # change prob for Species
colprob
   Sepal.Length  Sepal.Width Petal.Length  Petal.Width  Species 
0.5  0.5  0.5  0.5  1.0 
colprob[Sepal.Width] # example prob for Sepal.Width
   Sepal.Width 
   0.5

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

 
 
 
 
 Schalk Heunis-2 wrote:
  
  Hi Phil
  Try the following
  which(names(iris)=='Species')
  [1] 5
  
  HTH
  Schalk Heunis
  
  On Mon, Oct 12, 2009 at 8:53 AM, tdm ph...@philbrierley.com wrote:
  
 
  Hi,
 
  How do I access the index number of a field given I only 
 know the field
  name?
 
  eg - I want to set the probability of the field 'species' 
 higher than the
  other fields to use in sampling.
 
   colprob - array(dim=NCOL(iris))
   for(i in 1:NCOL(iris)){colprob[i]=0.5}
   colprob[iris$species] = 1 #this doesn't work
   colprob
  [1] 0.5 0.5 0.5 0.5 0.5
 
 
 
 
 
  --
  View this message in context:
  
 http://www.nabble.com/field-index-given-name.-tp25851216p25851216.html
  Sent from the R help mailing list archive at Nabble.com.
 
  __
  R-help@r-project.org mailing list
  https://stat.ethz.ch/mailman/listinfo/r-help
  PLEASE do read the posting guide
  http://www.R-project.org/posting-guide.html
  and provide commented, minimal, self-contained, reproducible code.
 
  
  [[alternative HTML version deleted]]
  
  __
  R-help@r-project.org mailing list
  https://stat.ethz.ch/mailman/listinfo/r-help
  PLEASE do read the posting guide
  http://www.R-project.org/posting-guide.html
  and provide commented, minimal, self-contained, reproducible code.
  
  
 
 -- 
 View this message in context: 
 http://www.nabble.com/field-index-given-name.-tp25851216p25851466.html
 Sent from the R help mailing list archive at Nabble.com.
 
 __
 R-help@r-project.org mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide 
 http://www.R-project.org/posting-guide.html
 and provide commented, minimal, self-contained, reproducible code.
 

__
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.