### String functions
#
# surveydata/R/strings.R by Andrie de Vries Copyright (C) 2011-2017
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 or 3 of the License
# (at your option).
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# A copy of the GNU General Public License is available at
# http://www.r-project.org/Licenses/
#
#' Finds the common and unique elements in a character vector.
#'
#' Function takes a character string as input and find the common and
#' unique elements. Assumes that the common element is at start of string.
#'
#' @param string Character vector
#' @return list of common and unique strings
#' @keywords string
#' @export
#' @family Strings
#' @examples
#' test <- c("Q_1", "Q_2", "Q_3")
#' strCommonUnique(test)$common
#' strCommonUnique(test)$unique
strCommonUnique <- function(string) {
x <- as.character(string)
y <- string
## Handles case with a single string element
if (length(x) <= 1) {
return(list(common = x[1], unique = ""))
}
## Handles case where all elements are identical
all_identical <- all(as.logical(lapply(x, function(f) x[1] == f)))
if (all_identical) {
return(list(common = x[1], unique = rep("", length(x))))
}
## Handles case where shortest element has length 0
if (min(nchar(x)) == 0) {
return(list(common = "", unique = x))
}
## Handles case where shortest element has length 1
if (min(nchar(x)) == 1) {
x1 <- sapply(x, function(f) {
unlist(strsplit(f, NULL))[1]
})
all_identical <- all(as.logical(lapply(x1, function(f) x1[1] == f)))
if (all_identical) {
return(
list(common = substr(x[1], 1, 1), unique = substr(x, 2, nchar(x)))
)
} else {
return(
list(common = "", unique = x)
)
}
}
# Make all strings the same length as shortest string
x1 <- substr(x, 1, min(nchar(x)))
# Create matrix of characters
split <- lapply(x1, function(f) {
unlist(strsplit(f, NULL))
})
# Test which characters are identical
identical <- sapply(split, function(f) {
f == split[[1]]
}) ### aaply
common <- apply(identical, 2, function(f) {
which(f == FALSE)[1]
}) ### aaply
mincommon <- min(common, na.rm = TRUE) - 1
# browser()
if (mincommon < 1) {
return(list(common = "", unique = x))
} else {
return(list(
common = substr(x[1], 1, mincommon),
unique = substr(x, mincommon + 1, nchar(x))
))
}
}
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