In lahstorti/FARS.functions: Assignment for Building R Packages

knitr::opts_chunk$set(echo = TRUE)

Introduction

The FARS.functions package uses data from the US National Highway Traffic Safety Administration's Fatality Analysis Reporting System (FARS) to plot a map with the fatalities in a specific US State during a specific year.

Functions

This package contains five functions:

1. fars_read(filename): reads data from a csv file in the CURRENT working directory and returns it as an object of the "tbl_df" class. This function uses the read_csv() function from the readr package to read the data. After that, the tbl_df() function from the dplyr package is called to convert the data into the tbl_df format before returing it.

Examples:

#file exists in current working directory

library(FARS.functions)

FARS.functions:::fars_read("accident_2014.csv.bz2")

#file doesn't exist in current working directory

library(FARS.functions)

FARS.functions:::fars_read("data123.csv.bz2")

#Error: file 'data123.csv' does not exist.

2. make_filename(year): uses the year (input) to generate the file name for the Fatality Analysis Reporting System (FARS) data file.

Examples:

library(FARS.functions)

FARS.functions:::make_filename(2014) #generates "accident_2014.csv.bz2"

library(FARS.functions)

FARS.functions:::make_filename("abcd") #generates "accident_NA.csv.bz2"

3. fars_read_years(year): reads Fatality Analysis Reporting System (FARS) data for multiple years. This function processes each element of a vector or list of years. To generate a file name with the year this function calls the supporting function make_filename(), and then calls the supporting function fars_read(), to read the FARS data file with the generated file name.

Examples:

library(FARS.functions)

FARS.functions:::fars_read_years(c(2014, 2015, 2016))

library(FARS.functions)

FARS.functions:::fars_read_years(c("2014", "2015", "2016"))

4. fars_summarize_years(year): summarizes Fatality Analysis Reporting System (FARS) data for multiple years into columns. This function produces a "tidy" data frame of FARS data for multiple yearsand the data is summarized by each month of each year with each year in its own column. This function uses fars_read_years() function to generate a list of month and year.

Examples:

library(FARS.functions)

FARS.functions:::fars_summarize_years(c(2014, 2015))

library(FARS.functions)

FARS.functions:::fars_summarize_years(c("2013", "2014"))

5. fars_map_state(state.num, year): creates a map with the fatalities in a US State during a year according to the Fatality Analysis Reporting System (FARS) database. This function takes the state number and a year as inputs and calls the supporting functions make_filename() and fars_read().

Examples:

library(FARS.functions)

FARS.functions:::fars_map_state(30, 2013)

library(FARS.functions)

FARS.functions:::fars_map_state(70, 2014)

#Error: "invalid STATE number: 70"

lahstorti/FARS.functions documentation built on May 15, 2019, 3:32 p.m.