R help - Feb 2011 - <environment: 0x000000000734f888> in object of class formula

# Hi all,

# I've made a function to make a formula out of a data.frame without columns
which contain a constant value.

# The function "which.constant" returns the indices of colums with
constant
values:

which.constant <- function(data.frame) { # counts the number of columns in a
data.frame which are constant
h <- sapply(sapply(data.frame,unique),length) # count unique values
return(as.numeric(which(h==1)))}

# The function "make.formula" returns the desired formula but with an
unwanted addition :

make.formula <- function(data.frame) {
    h <- which.constant(data.frame)
    hh <- names(data.frame)[-h]
    hh <-
paste("~",paste(hh,collapse="+"),sep="")
    return(as.formula(hh))}

# The following structure should give an example of how it works:

Data <- structure(list(cs_jail_2 = c(2L, 1L, 1L, 0L, 0L, 1L), cs_jail_3 c(0L,
0L, 0L, 0L, 0L, 0L), cs_jail_4 = c(1L, 2L, 2L, 2L, 0L, 0L)), .Names
c("cs_jail_2",
"cs_jail_3", "cs_jail_4"), row.names = c(NA, 6L), class =
"data.frame")

make.formula(Data)

# ~cs_jail_2 + cs_jail_4
# <environment: 0x0000000007654058>

# what does this <environment ...> mean?

# does it effect computation in any way? how to get read of it?

# thank you,

# Aviad
# aviadklein.wordpress.com/

	[[alternative HTML version deleted]]

Did you look at the help?  ?formula has a whole section about why 
formulas have environments and what they do.

On Fri, 4 Feb 2011, Aviad Klein wrote:
> # Hi all,
>
> # I've made a function to make a formula out of a data.frame without
columns
> which contain a constant value.
>
> # The function "which.constant" returns the indices of colums
with constant
> values:
>
> which.constant <- function(data.frame) { # counts the number of columns
in a
> data.frame which are constant
> h <- sapply(sapply(data.frame,unique),length) # count unique values
> return(as.numeric(which(h==1)))}
>
> # The function "make.formula" returns the desired formula but
with an
> unwanted addition :
>
> make.formula <- function(data.frame) {
>    h <- which.constant(data.frame)
>    hh <- names(data.frame)[-h]
>    hh <-
paste("~",paste(hh,collapse="+"),sep="")
>    return(as.formula(hh))}
>
> # The following structure should give an example of how it works:
>
> Data <- structure(list(cs_jail_2 = c(2L, 1L, 1L, 0L, 0L, 1L), cs_jail_3
> c(0L,
> 0L, 0L, 0L, 0L, 0L), cs_jail_4 = c(1L, 2L, 2L, 2L, 0L, 0L)), .Names >
c("cs_jail_2",
> "cs_jail_3", "cs_jail_4"), row.names = c(NA, 6L), class
= "data.frame")
>
> make.formula(Data)
>
> # ~cs_jail_2 + cs_jail_4
> # <environment: 0x0000000007654058>
>
> # what does this <environment ...> mean?
>
> # does it effect computation in any way? how to get read of it?
See also ?environment for how to remove (sic) it.
>
> # thank you,
>
> # Aviad
> # aviadklein.wordpress.com/
>
> 	[[alternative HTML version deleted]]
Please don't send HTML when expressly asked not to in the posting 
guide.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
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, UK                Fax:  +44 1865 272595