R: Create a normalised data set

Normalise.coin

R Documentation

Create a normalised data set

Description

Creates a normalised data set using specifications specified in global_specs. Columns of dset can also optionally be normalised with individual specifications using the indiv_specs argument. If indicators should have their directions reversed, this can be specified using the directions argument. Non-numeric columns are ignored automatically by this function. By default, this function normalises each indicator using the "min-max" method, scaling indicators to lie between 0 and 100. This calls the n_minmax() function. Note, all COINr normalisation functions are of the form n_*().

Usage

## S3 method for class 'coin'
Normalise(
  x,
  dset,
  global_specs = NULL,
  indiv_specs = NULL,
  directions = NULL,
  out2 = "coin",
  write_to = NULL,
  write2log = TRUE,
  ...
)

Arguments

`x`	A coin
`dset`	A named data set found in `.$Data`
`global_specs`	Specifications to apply to all columns, apart from those specified by `indiv_specs`. See details.
`indiv_specs`	Specifications applied to specific columns, overriding those specified in `global_specs`. See details.
`directions`	An optional data frame containing the following columns: `iCode` The indicator code, corresponding to the column names of the data set `Direction` numeric vector with entries either `-1` or `1` If `directions` is not specified, the directions will be taken from the `iMeta` table in the coin, if available.
`out2`	Either `"coin"` to return normalised data set back to the coin, or `df` to simply return a data frame.
`write_to`	Optional character string for naming the data set in the coin. Data will be written to `.$Data[[write_to]]`. Default is `write_to == "Normalised"`.
`write2log`	Logical: if `FALSE`, the arguments of this function are not written to the coin log, so this function will not be invoked when regenerating. Recommend to keep `TRUE` unless you have a good reason to do otherwise.
`...`	arguments passed to or from other methods.

Details

Global specification

The global_specs argument is a list which specifies the normalisation function and any function parameters that should be used to normalise the indicators found in the data set. Unless indiv_specs is specified, this will be applied to all indicators. The list should have two entries:

.$f_n: the name of the function to use to normalise each indicator
.$f_n_para: any further parameters to pass to f_n, apart from the numeric vector (each column of the data set)

In this list, f_n should be a character string which is the name of a normalisation function. For example, f_n = "n_minmax" calls the n_minmax() function. f_n_para is a list of any further arguments to f_n. This means that any function can be passed to Normalise(), as long as its first argument is x, a numeric vector, and it returns a numeric vector of the same length. See n_minmax() for an example.

f_n_para is required to be a named list. So e.g. if we define a function f1(x, arg1, arg2) then we should specify f_n = "f1", and f_n_para = list(arg1 = val1, arg2 = val2), where val1 and val2 are the values assigned to the arguments arg1 and arg2 respectively.

The default list for global_specs is: list(f_n = "n_minmax", f_n_para = list(l_u = c(0,100))), i.e. min-max normalisation between 0 and 100.

Note, all COINr normalisation functions (passed to f_n) are of the form n_*(). Type n_ in the R Studio console and press the Tab key to see a list.

This function includes a special case for "distance to target" normalisation. Setting global_specs = list(f_n = "n_dist2targ") will apply distance to target normalisation, automatically passing targets found in the "Target" column of iMeta.

Individual column specification

Optionally, indicators can be normalised with different normalisation functions and parameters using the indiv_specs argument. This must be specified as a named list e.g. list(i1 = specs1, i2 = specs2) where i1 and i2 are iCodes to apply individual normalisation to, and specs1 and specs2 are respectively lists of the same format as global_specs (see above). In other words, indiv_specs is a big list wrapping together global_specs-style lists. Any iCodes not named in indiv_specs ( i.e. those not in names(indiv_specs)) are normalised using the specifications from global_specs. So indiv_specs lists the exceptions to global_specs.

See also vignette("normalise") for more details.

Value

An updated coin

Examples

# build example coin
coin <- build_example_coin(up_to = "new_coin")

# normalise the raw data set
coin <- Normalise(coin, dset = "Raw")