str_pos: Find partial matching and close distance elements in strings

Description

This function finds the element indices of partial matching or similar strings in a character vector. Can be used to find exact or slightly mistyped elements in a string vector.

Usage

str_pos(searchString, findTerm, maxdist = 2, part.dist.match = 0, showProgressBar = FALSE)

Arguments

searchString

Character vector with string elements.

findTerm

String that should be matched against the elements of searchString.

maxdist

Maximum distance between two string elements, which is allowed to treat them as similar or equal. Smaller values mean less tolerance in matching.

part.dist.match

Activates similar matching (close distance strings) for parts (substrings) of the searchString. Following values are accepted:

0 for no partial distance matching
1 for one-step matching, which means, only substrings of same length as findTerm are extracted from searchString matching
2 for two-step matching, which means, substrings of same length as findTerm as well as strings with a slightly wider range are extracted from searchString matching

Default value is 0. See 'Details' for more information.

showProgressBar

Logical; f TRUE, the progress bar is displayed when computing the distance matrix. Default in FALSE, hence the bar is hidden.

Value

A numeric vector with index position of elements in searchString that partially match or are similar to findTerm. Returns -1 if no match was found.

Details

For part.dist.match = 1, a substring of length(findTerm) is extracted from searchString, starting at position 0 in searchString until the end of searchString is reached. Each substring is matched against findTerm, and results with a maximum distance of maxdist are considered as "matching". If part.dist.match = 2, the range of the extracted substring is increased by 2, i.e. the extracted substring is two chars longer and so on.

Examples

Run this code

## Not run: 
# string <- c("Hello", "Helo", "Hole", "Apple", "Ape", "New", "Old", "System", "Systemic")
# str_pos(string, "hel")   # partial match
# str_pos(string, "stem")  # partial match
# str_pos(string, "R")     # no match
# str_pos(string, "saste") # similarity to "System"
# 
# # finds two indices, because partial matching now
# # also applies to "Systemic"
# str_pos(string,
#         "sytsme",
#         part.dist.match = 1)
# 
# # finds nothing
# str_pos("We are Sex Pistols!", "postils")
# # finds partial matching of similarity
# str_pos("We are Sex Pistols!", "postils", part.dist.match = 1)## End(Not run)

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