In Juanin2691/fars: Summarize and graph data from FARS

library(dplyr)
library(readr)
library(tidyr)
library(maps)
library(graphics)

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)
}

make_filename <- function(year) {
        year <- as.integer(year)
        sprintf("accident_%d.csv.bz2", year)
}

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)
                })
        })
}

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)
}

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)
        })
}

This is a brief tutorial about how to use all the functions in the package fars. This package include functions for read, summarize and graph data directly from the current working directory. The data should came from Fatality Analysis Reporting System (FARS).

Make a name for a file

This package only uses file names following the convention:

accident_year.csv.bz2

Make this kind of names could be cumbersome, so you can simply use the function make_filename(year).

name_2013 <- make_filename(2013)
name_2013

Import data

With the rigth name, you can import data easily with the function fars_read.

```r
name_2014 <- make_filename(2014)
data_2014 <- fars_read(name_2014)
head(data_2014)

Sumarize data

For valid years and from files in the working directory, fars_summarize_years(years) makes a data frame with MONTH and years columns (one column per year). For each intersection between MONTH rows and year columns, it shows the data number.

years <- c(2013, 2014, 2015)
sum_years <- fars_summarize_years(years)
sum_years

Graph data

From a file in the working directory, fars_map_state() function makes a representation of a state with dots representing accidents. All previous for a valid state number and a valid year

fars_map_state(4, 2013)
fars_map_state(10, 2015)

Juanin2691/fars documentation built on May 9, 2019, 3:26 a.m.