| strcmp {RecordLinkage} | R Documentation |
Functions for computation of the similarity between two strings.
jarowinkler(str1, str2, W_1=1/3, W_2=1/3, W_3=1/3, r=0.5) levenshteinSim(str1, str2) levenshteinDist(str1, str2)
str1,str2 |
Two character vectors to compare. |
W_1,W_2,W_3 |
Adjustable weights. |
r |
Maximum transposition radius. A fraction of the length of the shorter string. |
String metrics compute a similarity value in the range [0,1] for two strings, with 1 denoting the highest (usually equality) and 0 denoting the lowest degree of similarity. In the context of Record Linkage, string similarities can improve the discernibility between matches and non-matches.
jarowinkler is an implementation of the algorithm by Jaro and Winkler
(see references). For the meaning of W_1, W_2, W_3 and
r see the referenced article. For most applications, the default
values are reasonable.
levenshteinDist returns the Levenshtein
distance, which cannot be directly used as a valid string comparator.
levenshteinSim is a similarity function based on
the Levenshtein distance, calculated by
1 - d(str1,str2) / max(A,B), where d is the Levenshtein distance
function and A and B are the lenghts of the strings.
Arguments str1 and str2 are expected to be of type
"character".
Non-alphabetical characters can be processed. Valid format combinations for
the arguments are:
Two arrrays with the same dimensions.
Two vectors. The shorter one is recycled as necessary.
A numeric vector with similarity values in the interval
[0,1]. For levenshteinDist, the edit distance as an
integer vector.
String comparison is case-sensitive, which means that for example
"R" and "r" have a similarity of 0. If this behaviour is undesired,
strings should be normalized before processing.
Andreas Borg, Murat Sariyar
Winkler, W.E.: String Comparator Metrics and Enhanced Decision Rules in the Fellegi-Sunter Model of Record Linkage. In: Proceedings of the Section on Survey Research Methods, American Statistical Association (1990), S. 354–369.
# compare two strings:
jarowinkler("Andreas","Anreas")
# compare one string with several others:
levenshteinSim("Andreas",c("Anreas","Andeas"))
# compare two vectors of strings:
jarowinkler(c("Andreas","Borg"),c("Andreas","Bork"))