Search Github: Big Mac Index  data
///////////////////////////////////////////////////////
 Search Github
   https://github.com/

  1) https://github.com/TheEconomist/big-mac-data
     https://github.com/TheEconomist/big-mac-data/blob/master/source-data/big-mac-historical-source-data.csv

   or 
    http://datayyy.com/data_csv/big-mac-source-data.csv
    http://datayyy.com/data_csv/big-mac-historical-source-data.csv

    http://datayyy.com/data_csvbig-mac-adjusted-index.csv
    http://datayyy.com/data_csvbig-mac-full-index.csv    
    http://datayyy.com/data_csvbig-mac-raw-index.csv     

    http://datayyy.com/data_excel/big-mac-2018-07-01.xls
    http://datayyy.com/data_excel/big-mac-2019-01-01.xls
    http://datayyy.com/data_excel/big-mac-2019-07-09.xls
    http://datayyy.com/data_excel/big-mac-2020-01-14.xls
    http://datayyy.com/data_excel/big-mac-2020-07-01.xls
    http://datayyy.com/data_excel/big-mac-2021-01-01.xls
////////////////////////////////////////////

IRR definition and its rule
////////////////////////////////

IRR stands for the Internal Rate of Return. It is the discount
     rate  at which the NPV equals zero. Its associated decision
    rule is given below. 

IRR Rule:  if IRR>Rc  ->   accept
           if IRR<Rc  ->   reject
              Rc the cost of capital
///////////////////////////////

Generate an R data set including all R packages 
///////////////////////////////////////////////////////
 Task: Write an R program to generate an R data set
       that contains all R packages

Procedure to get the input text file
-------------------------------------
      Step 1: go to https://www.r-project.org/

      Step 2: Click on 'CRAN' on the left-hand side

      Step 3: choose a mirror location in your country 

      Step 4: click on 'Packages' on the left-hand side

      Step 5: Click on the first table [sorted by date]

      Step 6: Copy-and-paste it to a text file
              and it will be your input text file. 

             Alternatively, input the following file 
                http://datayyy.com/data_txt/allRpackages.txt

      [Hint: key functions: readLines() and strsplit() ]

////////////////////////////////////////////