R help - Jan 2006 - Selecting data frame components by name - do you know a shorter way?

Hi! I suspect there must be an easy way to access components of a data frame by
name, i.e. the input should look like "name1 name2 name3 ..." and the
output be a data frame of those components with the corresponding names. I ´ve
been trying for hours, but only found the long way to do it (which is not
feasible, since I have lots of components to select):

 

dframe[names(dframe)=="name1" | dframe=="name2" |
dframe=="name3"]

 

Do you know a shortcut?

 

Michael


	[[alternative HTML version deleted]]

So you want to create a subset of a data frame?
with components "name1" "name2" "name3" ... 

dframe[, c("name1","name2","name3",...)]   

will do that

Doug



On Fri, 20 Jan 2006, Michael Reinecke wrote:
> Hi! I suspect there must be an easy way to access components of a data
frame by name, i.e. the input should look like "name1 name2 name3 ..."
and the output be a data frame of those components with the corresponding names.
I ?ve been trying for hours, but only found the long way to do it (which is not
feasible, since I have lots of components to select):
> 
>  
> 
> dframe[names(dframe)=="name1" | dframe=="name2" |
dframe=="name3"]
> 
>  
> 
> Do you know a shortcut?
> 
>  
> 
> Michael
> 
> 
> 	[[alternative HTML version deleted]]
> 
>

?subset

subset(dframe, select=c("name1", "name2",
"name3"))

Michael Reinecke wrote:
> Hi! I suspect there must be an easy way to access components of a data
frame by name, i.e. the input should look like "name1 name2 name3 ..."
and the output be a data frame of those components with the corresponding names.
I ??ve been trying for hours, but only found the long way to do it (which is not
feasible, since I have lots of components to select):
> 
>  
> 
> dframe[names(dframe)=="name1" | dframe=="name2" |
dframe=="name3"]
> 
>  
> 
> Do you know a shortcut?
> 
>  
> 
> Michael
> 
> 
> 	[[alternative HTML version deleted]]
> 
> 
> 
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On Fri, 2006-01-20 at 18:55 +0100, Michael Reinecke
wrote:
> Hi! I suspect there must be an easy way to access components of a data
> frame by name, i.e. the input should look like "name1 name2 name3
..."
> and the output be a data frame of those components with the
> corresponding names. I ve been trying for hours, but only found the
> long way to do it (which is not feasible, since I have lots of
> components to select):
> dframe[names(dframe)=="name1" | dframe=="name2" |
dframe=="name3"]
> Do you know a shortcut?
> Michael

See ?subset:

  subset(dframe, select = c(name1, name2, name3))

Alternatively, if the number of columns to remove is less than the
number of columns to select, you can precede the column names with a
"-"
as per standard indexing conventions. 

See the Details section and the examples in ?subset.

HTH,

Marc Schwartz