reclin (version 0.1.2)

identical: Comparison functions

Description

Comparison functions

Usage

identical()
jaro_winkler(threshold = 0.95)
lcs(threshold = 0.8)
jaccard(threshold = 0.8)

Arguments

threshold

threshold to use for the Jaro-Winkler string distance when creating a binary result.

Value

The functions return a comparison function (see details).

Details

A comparison function should accept two arguments: both vectors. When the function is called with both arguments it should compare the elements in the first vector to those in the second. When called in this way, both vectors have the same length. What the function should return depends on the methods used to score the pairs. Usually the comparison functions return a similarity score with a value of 0 indication complete difference and a value > 0 indicating similarity (often a value of 1 will indicate perfect similarity).

Some methods, such a score_problink and problink_em, can handle similarity scores, but also need binary values (0/FALSE = complete dissimilarity; 1/TRUE = complete similarity). In order to allow for this the comparison function is called with one argument.

When the comparison is called with one argument, it is passed the result of a previous comparison. The function should translate that result to a binary (TRUE/FALSE or 1/0) result. The result should not contain missing values.

The jaro_winkler, lcs and jaccard functions use the corresponding methods from stringdist except that they are transformed from a distance to a similarity score.

Examples

# NOT RUN {
cmp <- identical()
x <- cmp(c("john", "mary", "susan", "jack"), 
         c("johan", "mary", "susanna", NA))
# Applying the comparison function to the result of the comparison results 
# in a logical result, with NA's and values of FALSE set to FALSE
cmp(x)

cmp <- jaro_winkler(0.95)
x <- cmp(c("john", "mary", "susan", "jack"), 
         c("johan", "mary", "susanna", NA))
# Applying the comparison function to the result of the comparison results 
# in a logical result, with NA's and values below the threshold FALSE
cmp(x)

# }
# NOT RUN {
# }