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jpm miao

2013-May-23 07:05 UTC

[R] convert a character string to a name

Hi,
   From time to time I need to do the aggregation. To illustrate, I present
a toy example as below. In this example, the task is to aggregate x and y
by z with the function mean.
   Could I call the aggregation function with x_test, where
   x_test=c("x","y")? Thanks

Miao

> dftest<-data.frame(x=1:12, y=(1:12)%%4, z=(1:12)%%2)
> dftest    x y z
1   1 1 1
2   2 2 0
3   3 3 1
4   4 0 0
5   5 1 1
6   6 2 0
7   7 3 1
8   8 0 0
9   9 1 1
10 10 2 0
11 11 3 1
12 12 0 0> aggregate(cbind(x,y)~z, data=dftest, FUN=mean)  z x y
1 0 7 1
2 1 6 2> x_test=c("x","y")
> aggregate(cbind(x_test)~z, data=dftest, FUN=mean)Error in model.frame.default(formula = cbind(x_test) ~ z, data = dftest) :
  variable lengths differ (found for 'z')
a1aggregate(cbind(factor(x_test))~z, data=dftest, FUN=mean)
Error in model.frame.default(formula = cbind(factor(x_test)) ~ z, data dftest) :
  variable lengths differ (found for 'z')> aggregate(factor(x_test)~z, data=dftest, FUN=mean)Error in model.frame.default(formula = factor(x_test) ~ z, data = dftest) :
  variable lengths differ (found for 'z')

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arun

2013-May-23 07:19 UTC

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[R] convert a character string to a name

?with(dftest,aggregate(cbind(x,y),list(z),FUN=mean))
#? Group.1 x y
#1?????? 0 7 1
#2?????? 1 6 2


#or
library(plyr)
ddply(dftest,.(z),numcolwise(mean))
#? z x y
#1 0 7 1
#2 1 6 2
A.K.



----- Original Message -----
From: jpm miao <miaojpm at gmail.com>
To: r-help <r-help at r-project.org>
Cc: 
Sent: Thursday, May 23, 2013 3:05 AM
Subject: [R] convert a character string to a name

Hi,
?  From time to time I need to do the aggregation. To illustrate, I present
a toy example as below. In this example, the task is to aggregate x and y
by z with the function mean.
?  Could I call the aggregation function with x_test, where
?  x_test=c("x","y")? Thanks

Miao

> dftest<-data.frame(x=1:12, y=(1:12)%%4, z=(1:12)%%2)
> dftest? ? x y z
1?  1 1 1
2?  2 2 0
3?  3 3 1
4?  4 0 0
5?  5 1 1
6?  6 2 0
7?  7 3 1
8?  8 0 0
9?  9 1 1
10 10 2 0
11 11 3 1
12 12 0 0> aggregate(cbind(x,y)~z, data=dftest, FUN=mean)? z x y
1 0 7 1
2 1 6 2> x_test=c("x","y")
> aggregate(cbind(x_test)~z, data=dftest, FUN=mean)Error in model.frame.default(formula = cbind(x_test) ~ z, data = dftest) :
? variable lengths differ (found for 'z')
a1aggregate(cbind(factor(x_test))~z, data=dftest, FUN=mean)
Error in model.frame.default(formula = cbind(factor(x_test)) ~ z, data dftest) :
? variable lengths differ (found for 'z')> aggregate(factor(x_test)~z, data=dftest, FUN=mean)Error in model.frame.default(formula = factor(x_test) ~ z, data = dftest) :
? variable lengths differ (found for 'z')

??? [[alternative HTML version deleted]]

______________________________________________
R-help at 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.

jim holtman

2013-May-23 07:45 UTC

head link

[R] convert a character string to a name

try this:
>  dftest<-data.frame(x=1:12, y=(1:12)%%4, z=(1:12)%%2)
>  aggregate(cbind(x,y)~z, data=dftest, FUN=mean)  z x y
1 0 7 1
2 1 6 2>   x_test=c("x","y")
>   a <- formula(paste0('cbind('+                     , x_test[1]
+                     , ','
+                     , x_test[2]
+                     , ') ~ z'
+                     ))>  a
cbind(x, y) ~ z> aggregate(a, data = dftest, FUN = mean)  z x y
1 0 7 1
2 1 6 2>

On Thu, May 23, 2013 at 3:05 AM, jpm miao <miaojpm@gmail.com> wrote:
> Hi,
>    From time to time I need to do the aggregation. To illustrate, I present
> a toy example as below. In this example, the task is to aggregate x and y
> by z with the function mean.
>    Could I call the aggregation function with x_test, where
>    x_test=c("x","y")? Thanks
>
> Miao
>
>
> > dftest<-data.frame(x=1:12, y=(1:12)%%4, z=(1:12)%%2)
> > dftest
>     x y z
> 1   1 1 1
> 2   2 2 0
> 3   3 3 1
> 4   4 0 0
> 5   5 1 1
> 6   6 2 0
> 7   7 3 1
> 8   8 0 0
> 9   9 1 1
> 10 10 2 0
> 11 11 3 1
> 12 12 0 0
> > aggregate(cbind(x,y)~z, data=dftest, FUN=mean)
>   z x y
> 1 0 7 1
> 2 1 6 2
> > x_test=c("x","y")
> > aggregate(cbind(x_test)~z, data=dftest, FUN=mean)
> Error in model.frame.default(formula = cbind(x_test) ~ z, data = dftest) :
>   variable lengths differ (found for 'z')
> a1aggregate(cbind(factor(x_test))~z, data=dftest, FUN=mean)
> Error in model.frame.default(formula = cbind(factor(x_test)) ~ z, data >
dftest) :
>   variable lengths differ (found for 'z')
> > aggregate(factor(x_test)~z, data=dftest, FUN=mean)
> Error in model.frame.default(formula = factor(x_test) ~ z, data = dftest) :
>   variable lengths differ (found for 'z')
>
>         [[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.
>


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

	[[alternative HTML version deleted]]

Greg Snow

2013-May-23 14:07 UTC

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[R] convert a character string to a name

Here are a couple of approaches:
> dftest<-data.frame(x=1:12, y=(1:12)%%4, z=(1:12)%%2)
> x_test=c("x","y")
> aggregate( dftest[,x_test], dftest['z'], FUN=mean )  z x y
1 0 7 1
2 1 6 2>
> ### Or
>
> tmp.f <- as.formula( paste( 'cbind(',+   paste( x_test, collapse=',' ),
+ ') ~ z' ) )> aggregate( tmp.f, data=dftest, FUN=mean )  z x y
1 0 7 1
2 1 6 2


The first just uses x_test to subset the data frame and sends the
constructed subset to aggregate.  The second constructs the formula from
the strings and passes the formula to aggregate.



On Thu, May 23, 2013 at 1:05 AM, jpm miao <miaojpm@gmail.com> wrote:
> Hi,
>    From time to time I need to do the aggregation. To illustrate, I present
> a toy example as below. In this example, the task is to aggregate x and y
> by z with the function mean.
>    Could I call the aggregation function with x_test, where
>    x_test=c("x","y")? Thanks
>
> Miao
>
>
> > dftest<-data.frame(x=1:12, y=(1:12)%%4, z=(1:12)%%2)
> > dftest
>     x y z
> 1   1 1 1
> 2   2 2 0
> 3   3 3 1
> 4   4 0 0
> 5   5 1 1
> 6   6 2 0
> 7   7 3 1
> 8   8 0 0
> 9   9 1 1
> 10 10 2 0
> 11 11 3 1
> 12 12 0 0
> > aggregate(cbind(x,y)~z, data=dftest, FUN=mean)
>   z x y
> 1 0 7 1
> 2 1 6 2
> > x_test=c("x","y")
> > aggregate(cbind(x_test)~z, data=dftest, FUN=mean)
> Error in model.frame.default(formula = cbind(x_test) ~ z, data = dftest) :
>   variable lengths differ (found for 'z')
> a1aggregate(cbind(factor(x_test))~z, data=dftest, FUN=mean)
> Error in model.frame.default(formula = cbind(factor(x_test)) ~ z, data >
dftest) :
>   variable lengths differ (found for 'z')
> > aggregate(factor(x_test)~z, data=dftest, FUN=mean)
> Error in model.frame.default(formula = factor(x_test) ~ z, data = dftest) :
>   variable lengths differ (found for 'z')
>
>         [[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.
>


-- 
Gregory (Greg) L. Snow Ph.D.
538280@gmail.com

	[[alternative HTML version deleted]]

R help - May 2013 - convert a character string to a name

[R] convert a character string to a name

[R] convert a character string to a name

[R] convert a character string to a name

[R] convert a character string to a name