get_corr {COINr}

Get correlations

Description

Helper function for getting correlations between indicators and aggregates. This retrieves subsets of correlation matrices between different aggregation levels, in different formats. By default, it will return a long-form data frame, unless make_long = FALSE. By default, any correlations with a p-value less than 0.05 are replaced with NA. See pval argument to adjust this.

Usage

get_corr(
  coin,
  dset,
  iCodes = NULL,
  Levels = NULL,
  ...,
  cortype = "pearson",
  pval = 0.05,
  withparent = FALSE,
  grouplev = NULL,
  make_long = TRUE,
  use_directions = FALSE
)

Arguments

coin

A coin class coin object

dset

The name of the data set to apply the function to, which should be accessible in .$Data.

iCodes

An optional list of character vectors where the first entry specifies the indicator/aggregate codes to correlate against the second entry (also a specification of indicator/aggregate codes). If this is specified as a character vector it will coerced to the first entry of a list, i.e. list(iCodes).

Levels

The aggregation levels to take the two groups of indicators from. See get_data() for details. Defaults to indicator level.

...

Further arguments to be passed to get_data() (uCodes and use_group).

cortype

The type of correlation to calculate, either "pearson", "spearman", or "kendall".

pval

The significance level for including correlations. Correlations with p > pval will be returned as NA. Default 0.05. Set to 0 to disable this.

withparent

If TRUE, and aglev[1] != aglev[2], will only return correlations of each row with its parent. Alternatively, if withparent = "family", will return correlations with parents, grandparents etc, up to the highest level. In both cases the data set must be aggregated for this to work.

grouplev

The aggregation level to group correlations by if aglev[1] == aglev[2]. Requires that make_long = TRUE.

make_long

Logical: if TRUE, returns correlations in long format (default), else if FALSE returns in wide format. Note that if wide format is requested, features specified by grouplev and withparent are not supported.

use_directions

Logical: if TRUE the extracted data is adjusted using directions found inside the coin (i.e. the "Direction" column input in iMeta: any indicators with negative direction will have their values multiplied by -1 which will reverse the direction of correlation). This should only be set to TRUE if the data set has not yet been normalised. For example, this can be useful to set to TRUE to analyse correlations in the raw data, but would make no sense to analyse correlations in the normalised data because that already has the direction adjusted! So you would reverse direction twice. In other words, use this at your discretion.

Details

This function allows you to obtain correlations between any subset of indicators or aggregates, from any data set present in a coin. Indicator selection is performed using get_data(). Two different indicator sets can be correlated against each other by specifying iCodes and Levels as vectors.

The correlation type can be specified by the cortype argument, which is passed to stats::cor().

The withparent argument will optionally only return correlations which correspond to the structure of the index. For example, if Levels = c(1,2) (i.e. we wish to correlate indicators from Level 1 with aggregates from Level 2), and we set withparent = TRUE, only the correlations between each indicator and its parent group will be returned (not correlations between indicators and other aggregates to which it does not belong). This can be useful to check whether correlations of an indicator/aggregate with any of its parent groups exceeds or falls below thresholds.

Similarly, the grouplev argument can be used to restrict correlations to within groups corresponding to the index structure. Setting e.g. grouplev = 2 will only return correlations within the groups defined at Level 2.

The grouplev and withparent options are disabled if make_long = FALSE.

Note that this function can only call correlations within the same data set (i.e. only one data set in .$Data).

This function replaces the now-defunct getCorr() from COINr < v1.0.

Value

A data frame of pairwise correlation values in wide or long format (see make_long). Correlations with p > pval will be returned as NA.

See Also

• plot_corr() Plot correlation matrices of indicator subsets

Examples

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

# get correlations
cmat <- get_corr(coin, dset = "Raw", iCodes = list("Environ"),
                 Levels = 1, make_long = FALSE)