pxR (version 0.42.7)

as.px: Convert an array or a data.frame into an object of class px

Description

This function converts an array object into a px object. It uses the dimnames of the array to fill the VALUES list of the px object. It can also converts an data.frame object into a px object. Optionally it uses an object of type px as the skeleton of the new object.

Usage

as.px(x,... )
  # S3 method for array
as.px(x, skeleton.px = NULL, list.keys = NULL, ...)
  # S3 method for data.frame
as.px(x, skeleton.px = NULL,
                             list.keys = NULL, value.column = NULL,  ...)

Value

a px object

Arguments

x

An array or data.frame with the data required to build the px object

skeleton.px

A px object with metadata that will be used in the new px object

list.keys

A optional list of metadata pairs

value.column

Optional name to numeric value column in data.frame; defaults to "value"

...

Other arguments that can be passed to the function

Author

Francisco J. Viciana, Carlos J. Gil Bellosta,

Details

A px object is the internal representation in R of a PC-Axis file. As such, it contains both data and metadata.

The data to populate the px object comes from x, the first argument of the function. If x is an array, it needs to have 'named dimnames', i.e., its dimnames attribute needs to be a list with named entries.

x can also be a molten data.frame, i.e., each row contains a single value and the remaining columns indicate the levels of the variables it refers to. The ts names will be used in STUB and HEDING keyword of px objects. The first column of x will be used as 'HEADING', and the rest, in reverse, order as 'STUB'.

There are two compatible methods to provide metadata information. The first one is via skeleton.px, a px object whose metadata (title, etc.) is to be recycled in the new object. In addition to that, list.keys can be used to pass metadata in key-value pairs as shown in the examples below.

Metadata provided in list.keys has priority over metadata coming from skeleton.px. Also, note that the metadata items used to name the variables and their labels are neither extracted from skeleton.px nor px but from the dimnames attribute of x.

Note that the keywords 'HEADING', 'VALUES' and 'DATA', if present in skeleton.px or list.keys, are ignored. Inconsistent 'CODES' in skeleton.px will also be ignored.

Few checks are made to guarantee that metadata keys conform to the PC-Axis standard.

See Also

write.px, as.array.px

Examples

my.px.object  <- read.px(system.file("extdata", "example.px", package = "pxR"))
my.data       <- as.array(my.px.object)
my.px.object2 <- as.px(my.data)
my.px.object3 <- as.px(my.data, skeleton.px = my.px.object) 
my.px.object4 <- as.px(my.data, list.keys = list(MATRIX = "xxx", CONTENTS = "new data",
                             NEWKEY = "another key", UNITS = "people", TITLE = "My Title"))
                             
my.px.df      <- as.data.frame(my.px.object)
my.px.object5 <- as.px(my.px.df)