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# function Import March 14, 2017
# This add two arguments to the `import` file in the rio package
# import is just a front end to a number of file reading files and packages in R
# 3/14/2017: S. Weisberg, wrote the file, that adds
# row.names=TRUE, default, will select the left-most column of character data in the data file as
# row names subject to length(x) == length(unique(x))
# charAsFactor=TRUE converts character to factor if length(x) > length(unique(x))
# logicalAsFactor=charAsFactor converts logical to factor
# These arguments are read only if format %in% c("txt", "csv", "xls", "xlsx", "ods").
# 4/2/2017: S. Weisberg changed and simplified arguments.
# 5/22/2017: S. Weisberg, fixed bug reading files with one character column (added drop=FALSE)
# 5/6/2020: S. Weisberg, changed default for stringsAsFactors to FALSE.
# 11/2/2021: A. Zeileis, check for rio availability (so that rio can be in Suggests only)
Import <- function(file, format, ..., row.names=TRUE,
stringsAsFactors = FALSE){
if(!requireNamespace("rio")) stop("Import() relies on rio::import(), please install package 'rio'")
d <- rio::import(file, format, ...)
fmt <- if(!missing(format)) format else{
pos <- regexpr("\\.([[:alnum:]]+)$", file)
ifelse(pos > -1L, substring(file, pos + 1L), "")
}
# check for rows with no data
d <- d[!apply(d, 1, function(row) all(is.na(row))), ]
if(fmt %in% c("txt", "csv", "xls", "xlsx", "ods")){
classes <- unlist(lapply(as.list(d), class))
char <- classes %in% c("character", "logical")
if(!any(char)) return(d)
allUnique <- rep(FALSE, dim(d)[2])
allUnique[char] <- apply(d[, char, drop=FALSE], 2, function(x) length(x) == length(unique(x)))
if(row.names == TRUE){
if(any(allUnique)){
row.namesCol <- which(allUnique)[1] # use first non-repeating character col as row.names
row.names(d) <- d[[row.namesCol]] # set the row.names
d <- d[, -row.namesCol] # delete row.names column from data.frame
allUnique <- allUnique[-row.namesCol]
char <- char[-row.namesCol]}
}
if(stringsAsFactors & any(!allUnique)){
for(j in which(char & !allUnique)) d[, j] <- factor(d[, j])
}}
return(d)
}
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