R: Gower's distance

gower_dist {gower} | R Documentation

## Gower's distance

### Description

Compute Gower's distance, pairwise between records in two data sets `x` and `y`. Records from the smallest data set are recycled over.

### Usage

    gower_dist(x, y, pair_x = NULL, pair_y = NULL, eps = 1e-08,
      weights = NULL, ignore_case = FALSE,
      nthread = getOption("gd_num_thread"))

### Arguments

`x` | `[data.frame]`
`y` | `[data.frame]`
`pair_x` | `[numeric|character] (optional)` Columns in `x` used for comparison. See Details below.
`pair_y` | `[numeric|character] (optional)` Columns in `y` used for comparison. See Details below.
`eps` | `[numeric] (optional)` Computed numbers (variable ranges) smaller than `eps` are treated as zero.
`weights` | `[numeric] (optional)` A vector of weights of length `ncol(x)` that defines the weight applied to each component of the gower distance.
`ignore_case` | `[logical]` Toggle ignore case when neither `pair_x` nor `pair_y` are user-defined.
`nthread` | Number of threads to use for parallelization. By default, for a dual-core machine, 2 threads are used. For any other machine n-1 cores are used so your machine doesn't freeze during a big computation. The maximum nr of threads are determined using `omp_get_max_threads` at C level.

### Value

A `numeric` vector of length `max(nrow(x),nrow(y))`. When there are no columns to compare, a message is printed and both `numeric(0)` is returned invisibly.

### Details

There are three ways to specify which columns of `x` should be compared with what columns of `y`. The first option is do give no specification. In that case columns with matching names will be used. The second option is to use only the `pairs_y` argument, specifying for each column in `x` in order, which column in `y` must be used to pair it with (use `0` to skip a column in `x`). The third option is to explicitly specify the columns to be matched using `pair_x` and `pair_y`.

### Note

Gower (1971) originally defined a similarity measure (s, say) with values ranging from 0 (completely dissimilar) to 1 (completely similar). The distance returned here equals 1-s.

### References

Gower, John C. "A general coefficient of similarity and some of its properties." Biometrics (1971): 857-871.

### See Also

`gower_topn`

[Package gower version 0.2.1 Index]