#' Reads input file containing data regarding fatal injuries suffered in motor vehicle
#' traffic crashes.
#' @title Reading an input file.
#' @description This function checks whether a given file exists or not. If the file exists , it reads
#' the file into a data frame. Otherwise it throws an error with the message "File <filename> does not exists".
#' @param filename This can be either a variable holding the name of the file or the filename itself.
#' @return This function returns a data frame for the input file.
#' @details If the system is not able to locate the given file in the current working
#' directory or the complete filename is not provided, this function will throw an error.
#' @importFrom readr read_csv
#' @importFrom dplyr tbl_df
#' @examples
#' fars_read("accident_2013.csv")
#' fars_read("accident_2015.csv")
#' data1<-"data/accident.csv"
#' fars_read(data1)
#' @export
fars_read <- function(filename) {
if(!file.exists(filename))
stop("file '", filename, "' does not exist")
data <- suppressMessages({
readr::read_csv(filename, progress = FALSE)
})
dplyr::tbl_df(data)
}
#' @title Generating name of the input file based on year provided.
#' @description This function returns the name of the file by formatting it with user supplied
#' year.
#' @param year The year for which the information regarding fatal injuries is required. Valid value for <year>
#' will be those year for which user has "Accident_<year>.csv" file present in the local directory.
#' @return This function returns the name of the file for the year provided.
#' @examples
#' make_filename(2013)
#' yr<-2013
#' make_filename(yr)
#' make_filename(2015)
#' @export
make_filename <- function(year) {
year <- as.integer(year)
sprintf("accident_%d.csv", year)
}
#' @title Selecting and printing the months present in the input file for the given year.
#' @description This function creates the filename by appending user provided year to it.
#' It reads the file and selects the month present in the file for that year as well as the year also.
#' @inheritDotParams make_filename year
#' @return This function returns the year and the month present in the file for the selected year.
#' @details This function will throw an error if the year provided by user is not a valid year.
#' @importFrom dplyr mutate select
#' @examples
#' fars_read_years(2013)
#' fars_read_years(2015)
#' @export
fars_read_years <- function(years) {
lapply(years, function(year) {
file <- make_filename(year)
tryCatch({
dat <- fars_read(file)
dplyr::mutate(dat, year = year) %>%
dplyr::select(MONTH, year)
}, error = function(e) {
warning("invalid year: ", year)
return(NULL)
})
})
}
#' @title Total number of accidental injuries based on month for the given year.
#' @description This function reads the input file for the year provided by the user and
#' then returns the number of observation for each month of the given year.
#' @inheritDotParams make_filename year
#' @return This function returns the month and the total number of observation for each
#' month present in the file for the given year.
#' @details this function will throw an error if the year provided by user is not a valid year.
#' @importFrom dplyr bind_rows group_by summarize
#' @importFrom tidyr spread
#' @examples
#' fars_summarize_years(2013)
#' fars_summarize_years(2015)
#' @export
fars_summarize_years <- function(years) {
dat_list <- fars_read_years(years)
dplyr::bind_rows(dat_list) %>%
dplyr::group_by(year, MONTH) %>%
dplyr::summarize(n = n()) %>%
tidyr::spread(year, n)
}
#' @title Draws a geographical map for the accidental injuries for the given state and year.
#' @description This function reads the input file for the year provided by the user
#' and returns a geographical map depicting the fatal injuries suffered in motor vehicle
#' traffic crashes.
#' @inheritDotParams make_filename year
#' @param state Number for each state. For more information , \href{Fatality Analysis Reporting System}{Fatality Analysis Reporting System}.
#' @return This function returns a geographical map for the given state(s) with each dot as an obsevation
#' of the accidental injuries.
#' @details this function will throw an error if the year provided by user is not a valid year. For the definition on
#' valid year look at parameter 'year'.
#' @importFrom dplyr filter
#' @importFrom maps map
#' @importFrom graphics points
#' @examples
#' fars_map_state(1,2013)
#' fars_map_state(2,2015)
#' @export
fars_map_state <- function(state.num, year) {
filename <- make_filename(year)
data <- fars_read(filename)
state.num <- as.integer(state.num)
if(!(state.num %in% unique(data$STATE)))
stop("invalid STATE number: ", state.num)
data.sub <- dplyr::filter(data, STATE == state.num)
if(nrow(data.sub) == 0L) {
message("no accidents to plot")
return(invisible(NULL))
}
is.na(data.sub$LONGITUD) <- data.sub$LONGITUD > 900
is.na(data.sub$LATITUDE) <- data.sub$LATITUDE > 90
with(data.sub, {
maps::map("state", ylim = range(LATITUDE, na.rm = TRUE),
xlim = range(LONGITUD, na.rm = TRUE))
graphics::points(LONGITUD, LATITUDE, pch = 46)
})
}
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