R devel - Nov 2011 - One step way to create data frame with variable "variable names"?

Suppose

plotx <- "someName"
modx <- "otherName"
plotxRange <- c(10,20)
modxVals <- c(1,2,3)

It often happens I want to create a dataframe or object with plotx or
modx as the variable names.  But can't understand syntax to do that.

I can get this done in 2 steps, creating the data frame and then
assigning names, as in

newdf <- data.frame( c(1, 2, 3, 4), c(4, 4, 4, 4))
colnames(newdf) <- c(plotx, modx)

I was trying to hit this in one step, but can't find how.  If I could
get this in one step, it would simplify some book keeping, because
this current method requires me to build up the name vector to match
newdf, and sometimes I make mistakes.

After the data.frame already exists, I understand I can insert new
variables using the variable names with syntax like

newdf[[plotx]] <- c(23, 23, 23, 23)

PJ

-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas

On Fri, Nov 11, 2011 at 10:25 AM, Paul Johnson <pauljohn32 at gmail.com>
wrote:
> Suppose
>
> plotx <- "someName"
> modx <- "otherName"
> plotxRange <- c(10,20)
> modxVals <- c(1,2,3)
>
> It often happens I want to create a dataframe or object with plotx or
> modx as the variable names. ?But can't understand syntax to do that.
>
> I can get this done in 2 steps, creating the data frame and then
> assigning names, as in
>
> newdf <- data.frame( c(1, 2, 3, 4), c(4, 4, 4, 4))
> colnames(newdf) <- c(plotx, modx)
>
> I was trying to hit this in one step, but can't find how. ?If I could
> get this in one step, it would simplify some book keeping, because
> this current method requires me to build up the name vector to match
> newdf, and sometimes I make mistakes.
>
> After the data.frame already exists, I understand I can insert new
> variables using the variable names with syntax like
>
> newdf[[plotx]] <- c(23, 23, 23, 23)
>

Try this:

newdf <- setNames(data.frame( c(1, 2, 3, 4), c(4, 4, 4, 4)), c(plotx, modx))

-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

> plotx <- "someName"
> modx <- "otherName"
> data.frame( structure(list(c(1, 2, 3, 4)), names=plotx),
structure(list(c(4, 4, 4, 4)), names=modx))
  someName otherName
1        1         4
2        2         4
3        3         4
4        4         4

(I think this is more of an R-help question.)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 
> -----Original Message-----
> From: r-devel-bounces at r-project.org [mailto:r-devel-bounces at
r-project.org] On Behalf Of Paul Johnson
> Sent: Friday, November 11, 2011 7:25 AM
> To: R Devel List
> Subject: [Rd] One step way to create data frame with variable
"variable names"?
> 
> Suppose
> 
> plotx <- "someName"
> modx <- "otherName"
> plotxRange <- c(10,20)
> modxVals <- c(1,2,3)
> 
> It often happens I want to create a dataframe or object with plotx or
> modx as the variable names.  But can't understand syntax to do that.
> 
> I can get this done in 2 steps, creating the data frame and then
> assigning names, as in
> 
> newdf <- data.frame( c(1, 2, 3, 4), c(4, 4, 4, 4))
> colnames(newdf) <- c(plotx, modx)
> 
> I was trying to hit this in one step, but can't find how.  If I could
> get this in one step, it would simplify some book keeping, because
> this current method requires me to build up the name vector to match
> newdf, and sometimes I make mistakes.
> 
> After the data.frame already exists, I understand I can insert new
> variables using the variable names with syntax like
> 
> newdf[[plotx]] <- c(23, 23, 23, 23)
> 
> PJ
> 
> --
> Paul E. Johnson
> Professor, Political Science
> 1541 Lilac Lane, Room 504
> University of Kansas
> 
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