cover: Calculate The Number Of Combinations Of String Covering

In akin: Functional Utilities for Data Processing

Calculate The Number Of Combinations Of String Covering

Description

Calculates the cardinality of substring family (the covering) and returns valid elements.

Usage

cover(x, valid. = FALSE, wplot = FALSE)

Arguments

x	integer, length = 1 or character vector, length > 1, or character string
valid.	logical, default, FALSE. When TRUE, valid substrings are returned. Requires character or string
wplot	logical, FALSE. When TRUE, displays a plot of combinations versus number of characters in string

Details

This function finds the total, the minimum and the maximum number of combinations of individual string covering or returns a subset of valid substrings (i.e. elements of the string) by retaining even transpositions inside the combinations matrix.

NOTE 1: Herein, the covering represents the substring family that preserves the order of characters inside the string. Hence, the use of combinations instead of partial permutations, n!/(n-r)!, as the order inside each selection group r is irrelevant.

NOTE 2: Very long strings may result in memory allocation error when valid. = TRUE. Use fcommon instead.

NOTE 3: When x is an integer associated with an existing string, x must equal either nchar(string) or length(character).

Value

When valid. = FALSE a prettified named vector showing the total, minimum and maximum number of combinations for respective string covering. When valid. = TRUE, a character vector of valid substrings longer than 2 characters each. In both cases, a plot is returned when wplot = TRUE.

See Also

fcommon

Examples

if (interactive()) {

# 1. x is a character

# 1.1 A string
x = 'tyrvvsvltvlhqdwlngkeykck'

a = cover(x)
print(a)

# 1.2 A vector
x = strsplit(x, '')[[1]]

b = cover(x)
print(b)

# 2. An integer

n = length(x)
c = cover(n)
print(c)

# 3. Valid substrings with plot

d = cover(x, valid. = TRUE, wplot = TRUE)
print(head(d, 30))

}

akin documentation built on May 19, 2026, 5:07 p.m.