The R package GrpString is originally developed for analyzing and comparing groups of scanpaths in eye-tracking studies. However, it is ideal for string analysis in general, especially for quantifying differences between two groups of strings. Here is the flow chart showing most functions in the current version (0.3.1).
Some examples:
library(GrpString)
# Discover patterns in a string vector:
strs.vec <- c(“ABCDdefABCDa”, “def123DC”, “123aABCD”, “ACD13”, “AC1ABC”, “3123fe”)
CommonPatt(strs.vec, low = 30)
# Compute transition entropy for each string:
stra.vec <- c(“ABCDdefABCDa”, “def123DC”, “A”, “123aABCD”, “ACD13”, “AC1ABC”, “3123fe”
TransEntropy(stra.vec)
# Statistical difference between two groups of strings:
strs1.vec <- c(“ABCDdefABCDa”, “def123DC”, “123aABCD”, “ACD13”, “AC1ABC”, “3123fe”)
strs2.vec <- c(“xYZdkfAxDa”, “ef1563xy”, “BC9Dzy35X”, “AkeC1fxz”, “65CyAdC”, “Dfy3f69k”)
ld.dif.vec <- StrDif(strs1.vec, strs2.vec, num_perm = 500, p.x = 0.025)

The package is available for download and install on CRAN, and you can find the latest version on GitHub.