R help - Oct 2010 - extracting characteristics of datasets from data()

I can use data() to find the available datasets in a package, but I'd 
like to extract and display some additional
information for each dataset  than what is provided by data(), e.g., 
class() and dim() for datasets for which
these are available.  I'm stuck on using using lapply properly with 
objects, rather than the names of objects
that I get from data()

Example:

 > DS <- data(package="vcdExtra")
 > DS$results[,c("Item", "Title")]
       Item          Title
  [1,] "Abortion"    "Abortion Opinion Data"
  [2,] "Bartlett"    "Bartlett data on plum root cuttings"
  [3,] "Caesar"      "Risk Factors for Infection in Caesarian
Births"
  [4,] "Cancer"      "Survival of Breast Cancer Patients"
  [5,] "Detergent"   "Detergent preference data"
  [6,] "Dyke"        "Sources of knowledge of cancer"
  [7,] "GSS"         "General Social Survey-- Sex and Party
affiliation"
  [8,] "Gilby"       "Clothing and Intelligence Rating of
Children"
  [9,] "Heart"       "Sex, Occupation and Heart Disease"
[10,] "Heckman"     "Labour Force Participation of Married Women
1967-1971"
[11,] "Hoyt"        "Minnesota High School Graduates"
[12,] "ICU"         "Death in the ICU"
[13,] "JobSat"      "Cross-classification of job satisfaction by
income"
[14,] "Mental"      "Mental impariment and parents SES"
[15,] "Mobility"    "Social Mobility data"
[16,] "TV"          "TV Viewing Data"
[17,] "Vietnam"     "Student Opinion About the War in
Vietnam"
[18,] "Yamaguchi87" "Occupational Mobility in Three
Countries"
 > unlist(lapply(as.list(DS$results[,c("Item") ]), FUN=class))
  [1] "character" "character" "character"
"character" "character"
"character" "character"
  [8] "character" "character" "character"
"character" "character"
"character" "character"
[15] "character" "character" "character"
"character"

Wanted: something like the results of doing

 > class(Abortion)
[1] "table"
 > dim(Abortion)
[1] 2 2 2
 > class(Mental)
[1] "data.frame"
 > dim(Mental)
[1] 24  3
 >
for all datasets in Item, giving a display like

Item      class       dim     Title
Abortion  table       2x2x2   Abortion Opinion Data
Mental    data.frame  24x2    Mental impariment and parents SES

-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street    Web:   http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA

> Michael writes:
> I can use data() to find the available datasets in a package, but I'd 
> like to extract and display some additional
> information for each dataset  than what is provided by data(), e.g., 
> class() and dim() for datasets for which
> these are available.
> ...
> for all datasets in Item, giving a display like
> 
> Item      class       dim     Title
> Abortion  table       2x2x2   Abortion Opinion Data
> Mental    data.frame  24x2    Mental impariment and parents SES
This seems to work on your example:
require('vcdExtra')
ds <-
as.data.frame(data(package="vcdExtra")$results[,c('Item','Title')],
stringsAsFactors=FALSE)
ds$dim <- lapply(ds$Item, function(x) { paste(dim(get(x)),
collapse='x') }
)
ds$class <- lapply(ds$Item, function(x) { class(get(x)) } )
ds <- ds[c('Item','class','dim','Title')]

Thanks for the fun exercise.  I've just started looking at the various 
'apply-oid' functions, having spent much of my time with aggregate() and
perhaps having my imagination stunted.

cur
-- 
Curt Seeliger, Data Ranger
Raytheon Information Services - Contractor to ORD
seeliger.curt@epa.gov
541/754-4638


	[[alternative HTML version deleted]]

Try this:

data(list = DS$results[,'Item'], package = 'vcdExtra', envir =
ne <-
new.env())
cbind(do.call(rbind, eapply(ne, function(x)data.frame(class = class(x), dim
= paste(dim(x), collapse = 'x')))), Title =
DS$results[,'Title'])

On Mon, Oct 25, 2010 at 1:45 PM, Michael Friendly <friendly@yorku.ca>
wrote:
> I can use data() to find the available datasets in a package, but I'd
like
> to extract and display some additional
> information for each dataset  than what is provided by data(), e.g.,
> class() and dim() for datasets for which
> these are available.  I'm stuck on using using lapply properly with
> objects, rather than the names of objects
> that I get from data()
>
> Example:
>
> > DS <- data(package="vcdExtra")
> > DS$results[,c("Item", "Title")]
>      Item          Title
>  [1,] "Abortion"    "Abortion Opinion Data"
>  [2,] "Bartlett"    "Bartlett data on plum root
cuttings"
>  [3,] "Caesar"      "Risk Factors for Infection in Caesarian
Births"
>  [4,] "Cancer"      "Survival of Breast Cancer
Patients"
>  [5,] "Detergent"   "Detergent preference data"
>  [6,] "Dyke"        "Sources of knowledge of cancer"
>  [7,] "GSS"         "General Social Survey-- Sex and Party
affiliation"
>  [8,] "Gilby"       "Clothing and Intelligence Rating of
Children"
>  [9,] "Heart"       "Sex, Occupation and Heart Disease"
> [10,] "Heckman"     "Labour Force Participation of Married
Women 1967-1971"
> [11,] "Hoyt"        "Minnesota High School Graduates"
> [12,] "ICU"         "Death in the ICU"
> [13,] "JobSat"      "Cross-classification of job
satisfaction by income"
> [14,] "Mental"      "Mental impariment and parents SES"
> [15,] "Mobility"    "Social Mobility data"
> [16,] "TV"          "TV Viewing Data"
> [17,] "Vietnam"     "Student Opinion About the War in
Vietnam"
> [18,] "Yamaguchi87" "Occupational Mobility in Three
Countries"
> > unlist(lapply(as.list(DS$results[,c("Item") ]), FUN=class))
>  [1] "character" "character" "character"
"character" "character"
> "character" "character"
>  [8] "character" "character" "character"
"character" "character"
> "character" "character"
> [15] "character" "character" "character"
"character"
>
> Wanted: something like the results of doing
>
> > class(Abortion)
> [1] "table"
> > dim(Abortion)
> [1] 2 2 2
> > class(Mental)
> [1] "data.frame"
> > dim(Mental)
> [1] 24  3
> >
> for all datasets in Item, giving a display like
>
> Item      class       dim     Title
> Abortion  table       2x2x2   Abortion Opinion Data
> Mental    data.frame  24x2    Mental impariment and parents SES
>
> --
> Michael Friendly     Email: friendly AT yorku DOT ca
> Professor, Psychology Dept.
> York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
> 4700 Keele Street    Web:   http://www.datavis.ca
> Toronto, ONT  M3J 1P3 CANADA
>
> ______________________________________________
> 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]