col_types <- function(dir, pattern, n=5, fctr_cols, sep = '', ...){
# read in first five rows of a file to define class of variables
#
# Args:
# dir: directory of the file
# pat: pattern to match
# char_cols: columns to assign character class
# num_cols: columns to assign number class
# n: number of rows to read
# Returns:
# column name and classes for increased fread speed
read_data <- dir(path = dir, pattern = pattern, full.names = TRUE, ...)
init_row <- read.table(read_data[[1]]
, na.strings = '?'
, header = TRUE
, stringsAsFactors = TRUE
, nrows = n
, check.names = FALSE
, sep = sep
)
init_row[,fctr_cols] <- sapply(init_row[,fctr_cols], as.factor)
# init_row[,char_cols] <- sapply(init_row[,char_cols], as.character)
# init_row[,num_cols] <- sapply(init_row[,num_cols], as.numeric)
classes <- sapply(init_row, class)
list('classes' = classes, files = read_data, sample = init_row, fctr_cols)
}
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