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getCommonPrefix <- function(strs, suffix=FALSE, ...) {
# Split strings into character vectors
nchars <- sapply(strs, FUN=nchar);
chars <- strsplit(strs, split="");
# Asked for the suffix?
if (suffix) {
chars <- lapply(chars, FUN=rev);
}
# Put the characters into a matrix
naValue <- as.character(NA);
data <- matrix(naValue, nrow=length(chars), ncol=max(nchars));
for (kk in seq_along(chars)) {
cc <- seq_len(nchars[kk]);
data[kk,cc] <- chars[[kk]];
}
# Find first column with different characters
count <- 0;
for (cc in seq_len(ncol(data))) {
uchars <- unique(data[,cc]);
if (length(uchars) > 1)
break;
count <- cc;
}
# The common prefix as a character vector
prefix <- chars[[1]][seq_len(count)];
# Asked for the suffix?
if (suffix) {
prefix <- rev(prefix);
}
# The common prefix as a character string
prefix <- paste(prefix, collapse="");
prefix;
} # getCommonPrefix()
##############################################################################
# HISTORY:
# 2010-07-05
# o Now getCommonPrefix() allocates a character matrix with NAs, and no
# longer a logical NA matrix.
# 2006-12-15
# o Created (since stringTree() is broken and this is good enough).
##############################################################################
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