# -----------------------------------------------------------------------------
# R programming statements for h206g data
#
# This file contains programming statements needed to import the ASCII data 
# file (.dat) into R. The R programming language has the capability to produce
# appropriate standard errors for estimates from a survey with a complex sample 
# design such as the Medical Expenditure Panel Survey (MEPS).
# 
# The input file is the ASCII data file (h206g.dat) supplied in this PUF 
# release, which can be extracted from the .zip file supplied at the MEPS 
# website: https://meps.ahrq.gov/mepsweb/data_stats/download_data_files.jsp
#
# This code imports the MEPS data into R as a data frame called 'h206g'.
#  
# Note that additional packages are needed to successfully run this code. To 
# install these packages, run the 'install.packages' function (shown below). 
# Once installed, the packages can be called using the 'library' function. 
# Packages only need to be installed once, but they must be called using the 
# 'library' function every time a new R session is started.
#
# Two options are available to run this code:
#
#  1. Copy and paste the code into an interactive R session. 
#
#     The user must first download the ASCII (.dat) file from the MEPS website
#     and save it to a local directory, which must be defined in the 
#     'meps_path' variable below. In this example, the local directory is  
#     called "C:/MEPS". Note that the path structure will differ on Mac and PC.  
# 
#
#  2. Call this code directly from an interactive R session. 
#
#     (a) If the ASCII (.dat) file has already been downloaded from the MEPS  
#         website and saved to a local directory, the following code can be run 
#         (after re-defining the 'meps_path' variable to point to the location 
#         of the h206g.dat file.)
#
#           meps_path <- "C:/MEPS/h206g.dat"  
#           source("https://meps.ahrq.gov/mepsweb/data_stats/download_data/pufs/h206g/h206gru.txt")
#           head(h206g) # view data
#
#
#     (b) Alternatively, the ASCII (.dat) file can be downloaded directly from
#         the MEPS website. The following code can be used to download and 
#         import the h206g data into R without having to manually download, 
#         unzip, and store the file on your local computer.
#
#           url <- "https://meps.ahrq.gov/mepsweb/data_files/pufs/h206gdat.zip"
#           download.file(url, temp <- tempfile())
#
#           meps_path <- unzip(temp, exdir = tempdir())
#           source("https://meps.ahrq.gov/mepsweb/data_stats/download_data/pufs/h206g/h206gru.txt")
#
#           unlink(temp)  # Unlink to delete temporary file
#
#           head(h206g) # view data
#
# -----------------------------------------------------------------------------


# DEFINE 'meps_path' -----------------------------------------------------------
# 'meps_path' should point to the file path of the ASCII file (h206g.dat) 
# Here, the 'exists' function checks whether meps_path is already defined. This
# feature is useful if calling this file from an external source.

if(!exists("meps_path")) 
  meps_path = "C:/MEPS/h206g.dat"  


# INSTALL PACKAGES ------------------------------------------------------------
# Uncomment and run this portion if packages are not yet installed
#
# install.packages("readr")


# LOAD PACKAGES ---------------------------------------------------------------
# Run this for every new R session

library(readr)


# DATA FILE INFO --------------------------------------------------------------

# Define start and end positions to read fixed-width file 

pos_start <- 
  c(1, 8, 11, 21, 37, 38, 52, 54, 55, 56, 60, 62, 64, 66, 69,
    71, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 95, 97, 100,
    103, 111, 119, 126, 135, 143, 151, 159, 166, 173, 181, 188,
    196, 205, 214, 215, 227, 231)

pos_end <- 
  c(7, 10, 20, 36, 37, 51, 53, 54, 55, 59, 61, 63, 65, 68, 70,
    73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 94, 96, 99, 102,
    110, 118, 125, 134, 142, 150, 158, 165, 172, 180, 187, 195,
    204, 213, 214, 226, 230, 231)

# Define variable names and types ('c' = character, 'n' = 'numeric') 

var_names <- 
  c("DUID", "PID", "DUPERSID", "EVNTIDX", "EVENTRN", "FFEEIDX",
    "PANEL", "MPCELIG", "MPCDATA", "OBDATEYR", "OBDATEMM",
    "SEEDOC_M18", "DRSPLTY_M18", "MEDPTYPE_M18", "DOCATLOC",
    "VSTCTGRY", "VSTRELCN_M18", "LABTEST_M18", "SONOGRAM_M18",
    "XRAYS_M18", "MAMMOG_M18", "MRI_M18", "EKG_M18",
    "RCVVAC_M18", "SURGPROC", "MEDPRESC", "FFOBTYPE",
    "FFBEF18", "FFTOT19", "OBSF18X", "OBMR18X", "OBMD18X",
    "OBPV18X", "OBVA18X", "OBTR18X", "OBOF18X", "OBSL18X",
    "OBWC18X", "OBOR18X", "OBOU18X", "OBOT18X", "OBXP18X",
    "OBTC18X", "IMPFLAG", "PERWT18F", "VARSTR", "VARPSU")

var_types <- 
  c("n", "n", "c", "c", "n", "c", "n", "n", "n", "n", "n", "n",
    "n", "n", "n", "n", "n", "n", "n", "n", "n", "n", "n", "n",
    "n", "n", "n", "n", "n", "n", "n", "n", "n", "n", "n", "n",
    "n", "n", "n", "n", "n", "n", "n", "n", "n", "n", "n")

var_types <- setNames(var_types, var_names)

# IMPORT ASCII (.dat) file ----------------------------------------------------

h206g <- read_fwf(
  meps_path,
  col_positions = 
    fwf_positions(
      start = pos_start, 
      end   = pos_end, 
      col_names = var_names),
  col_types = var_types)


# OPTIONAL: save as .Rdata file for easier loading ----------------------------
# Run this to save a permanent .Rdata file in the local working directory
#
# save(h206g, file = "h206g.Rdata")

# -----------------------------------------------------------------------------
# NOTES:
# 
#  1. This program has been tested on R version 3.6.0
#
#  2. This program will create a temporary data frame in R called 'h206g'.
#     You must run the 'save' command to permanently save the data to a local
#     folder
# -----------------------------------------------------------------------------