R: I have to do Softmatch in String

Question

I have to do softmatch in one column of data frame with the given input string, like

col <- c("John Collingson","J Collingson","Dummy Name1","Dummy Name2")

inputText <- "J Collingson"
#Vice-Versa
inputText <- "John Collingson"

I want to retrieve both "John Collingson" & "J Collingson" from the provided colname "col"

Kindly help

Answer 1

agrep is definitely a quick and easy base R solution if you have just a bit of data. If this is just a toy example of a larger data frame, you may be interested in a more durable tool. In the past month, learning about the Levenshtein distance noted by @PaulHiemstra (also in these different questions ) led me to theRecordLinkage package. The vignettes leave me wanting more examples of the "soft" or fuzzy" matches, particularly across more than 1 field, but the basic answer to your question could be somthing like:

library(RecordLinkage)
col <- data.frame(names1 = c("John Collingson","J Collingson","Dummy Name1","Dummy Name2"))
inputText <- data.frame(names2 = c("J Collingson"))
g1 <- compare.linkage(inputText, col, strcmp = T)
g2 <- epiWeights(g1)
getPairs(g2, min.weight=0.6) 
# id          names2 Weight
# 1  1    J Collingson       
# 2  2    J Collingson  1.000
# 3                          
# 4  1    J Collingson       
# 5  1 John Collingson  0.815

inputText2 <- data.frame(names2 = c("Jon Collinson"))
g1 <- compare.linkage(inputText2, col, strcmp = T)
g2 <- epiWeights(g1)
getPairs(g2, min.weight=0.6)
# id          names2    Weight
# 1  1   Jon Collinson          
# 2  1 John Collingson 0.9644444
# 3                             
# 4  1   Jon Collinson          
# 5  2    J Collingson 0.7924825

Please start with compare.linkage() or compare.dedup()-- RLBigDataLinkage() or RLBigDataDedup() for large data sets. Hope this helps.

Answer 2

It seems that agrep is the function you are looking for. It does Approximate String Matching (Fuzzy Matching) . It returns the closest match to the input pattern according to some distance measure, ie the generalized Levenshtein edit distance. See ?agrep for more details.

agrep("J Collingson", col, value = TRUE)
[1] "John Collingson" "J Collingson"