French Republican date conversion

Question

This program converts a date given from the French Republican Calendar to the corresponding date in our standard Gregorian Calendar. I'm looking for some improvements that I should start making in my code as well as some tips on how to write less lengthy code.

For example, the RepubtoGregDate function is very long and I believe there is probably a more effective way of implementing it.

I'm very new to Python and have no prior knowledge in programming so it would nice to have some suggestions in how to improve my code.

#Python Assignment - French Republican to Gregorian Date Convertor
#Coded by - -
import sys

def Main():
  Startup()
  while True:
    dayN, monthN, yearN, date = Date()
    StopProgram(date)
    ValidDate = DateVal(yearN, monthN, dayN)
    ValLoop(ValidDate)
    monthW = MonthNtoW(monthN)
    yearRN = YearNtoRN(yearN)
    RepubDate = FullRepubDate(dayN, monthW, yearRN)
    Leap = LeapCheck(yearN)
    GrDate = RepubtoGregDate(yearN, monthN, dayN, Leap)

def Startup():
  print("Republican to Gregorian Date Converter\n")
  print("This program will convert a date from the French Republican Calendar to the equivalent date in the Gregorian Calendar.")
  print("To stop calculating dates and close the program, simply input: 0 0 0.\n")

      # Asks for a Republican Date and returns day, month and year.
def Date():
  print("Input a Republican Date in the format: dd mm yy.")
  date = input("Please enter a Republican Date: ")
  print("")
  date = date.split()
  dayN = int(date[0])
  monthN = int(date[1])
  yearN = int(date[2])
  return(dayN, monthN, yearN, date)

      # Ends the program if the sentinal is matched.
def StopProgram(date):
  if date == ['0', '0', '0']:
    sys.exit(print("Program Closed."))

      # Validates the date, making sure it fits the Republican format and that
      # the date is between the calendars real world use: 1793 - 1806.
def DateVal(yearN, monthN, dayN):
  if yearN >= 1 and yearN <= 14:
    ValidYear = True
  else:
    ValidYear = False
  if monthN >= 1 and monthN <= 12:
    ValidMonth = True
  else:
    ValidMonth = False
  if dayN >= 1 and dayN <= 30:
    ValidDay = True
  else:
    ValidDay = False
  if yearN < 2 and monthN < 1 and dayN < 14:
    InvalidDate = True
  elif yearN > 14 and monthN > 4 and dayN > 11:
    InvalidDate = True
  else:
    InvalidDate = False
  if ValidYear == True and ValidMonth == True and ValidDay == True and InvalidDate == False:
    ValidDate = True
  else:
    ValidDate = False
  return(ValidDate)

      # Repeats the Date() Function if the Date is invalid.
def ValLoop(ValidDate):
  while ValidDate == False:
    print("The entered date was not a valid gregorian date, please try again.")
    dayN, monthN, yearN = Date()

      # Finds the month number's corresponding month word.
def MonthNtoW(monthN):
  MonthWDict = {1 : "Vendémiaire", 2 : "Brumaire", 3 : "Frimaire", 4 : "Nivôse", 5 : "Pluviôse", 6 : "Ventôse", 7 : "Germinal", 8 : "Floréal", 9 : "Prairial", 10 : "Messidor", 11 : "Thermidor", 12 : "Fructidor"}
  monthW = MonthWDict[monthN]
  return monthW

      # Finds the year number's corresponding year in roman numerals.
def YearNtoRN(yearN):
  YearRNDict = {1 : "I", 2 : "II", 3 : "III", 4 : "IV", 5 : "V", 6 : "VI", 7 : "VII", 8 : "VIII", 9 : "IX", 10 : "X", 11 : "XI", 12 : "XII", 13 : "XIII", 14 : "XIV"}
  yearRN = YearRNDict[yearN]
  return(yearRN)

      # Outputs the Republican date in its written format.
def FullRepubDate(dayN, monthW, yearRN):
  dayN = str(dayN)
  RepubDate = dayN + " " + monthW + " an " + yearRN
  print("The French Republican Date is: ", RepubDate)
  dayN = int(dayN)
  return(RepubDate)

      # Checks if the year is a leap year.
def LeapCheck(yearN):
  if yearN == 3 or yearN == 7 or yearN == 11:
    Leap = True
  else:
    Leap = False
  return(Leap)

      # Converts the Republican date to a Gregorian date.
      # It does this by converting the date to days in the year and then adds
      # that to the day the Republican Calendar started in The Gregorian calendar.
def RepubtoGregDate(yearN, monthN, dayN, Leap):
  monthL = 30
  StartDate = 266
  StartYear = 1792
  YDays = 365
  LYDays = 366

  Year = StartYear + (yearN - 1)
  Day = ((monthN - 1) * monthL) + dayN
  if Leap == True and Day >= 60:
    Day += 1

  PH = StartDate + Day
  if Leap == True:
    if PH > LYDays:
      Year += 1
      Day = PH - LYDays
    else:
      Day = PH     
  if Leap == False:
    if PH > YDays:
      Year += 1
      Day = PH - YDays
    else:
      Day = PH

  if Leap == False:
    if Day >= 1 and Day <= 31:
        GregMonth = "January"
    if Day >= 32 and Day <= 59:
        Day -= 31
        GregMonth = "February"
    if Day >= 60 and Day <= 90:
        Day -= 59
        GregMonth = "March"
    if Day >= 91 and Day <= 120:
        Day -= 90
        GregMonth = "April"
    if Day >= 121 and Day <= 151:
        Day -= 120
        GregMonth = "May"
    if Day >= 152 and Day <= 181:
        Day -= 151
        GregMonth = "June"
    if Day >= 182 and Day <= 212:
        Day -= 181
        GregMonth = "July"
    if Day >= 213 and Day <= 243:
        Day -= 212
        GregMonth = "August"
    if Day >= 244 and Day <= 273:
        Day -= 243
        GregMonth = "September"
    if Day >= 274 and Day <= 304:
        Day -= 273
        GregMonth = "October"
    if Day >= 305 and Day <= 334:
        Day -= 304
        GregMonth = "November"
    if Day >= 335 and Day <= 365:
        Day -= 334
        GregMonth = "December"

  if Leap == True:
    if Day >= 1 and Day <= 31:
        GregMonth = "January"
    if Day >= 32 and Day <= 60:
        Day -= 32
        GregMonth = "February"
    if Day >= 61 and Day <= 91:
        Day -= 60
        GregMonth = "March"
    if Day >= 92 and Day <= 121:
        Day -= 91
        GregMonth = "April"
    if Day >= 122 and Day <= 152:
        Day -= 121
        GregMonth = "May"
    if Day >= 153 and Day <= 182:
        Day -= 152
        GregMonth = "June"
    if Day >= 183 and Day <= 213:
        Day -= 182
        GregMonth = "July"
    if Day >= 214 and Day <= 244:
        Day -= 213
        GregMonth = "August"
    if Day >= 245 and Day <= 274:
        Day -= 244
        GregMonth = "September"
    if Day >= 275 and Day <= 305:
        Day -= 274
        GregMonth = "October"
    if Day >= 306 and Day <= 335:
        Day -= 305
        GregMonth = "November"
    if Day >= 336 and Day <= 366:
        Day -= 335
        GregMonth = "December"

  Day = str(Day)
  Year = str (Year)
  GregDate = Day + " " + GregMonth + " " + Year
  Day = int(Day)
  Year = int(Year)
  print("The Gregorian Date is: ", GregDate, "\n")
  return(GregDate)

#Main
Main()

Answer 1

Running your code through PEP8 will produce alot of errors, you can see it for yourself.

Just to name a few PEP8 improvements:

1. Use indentation of 4 spaces, it looks cleaner
2. Functions should be named with lowerscore letters. Example: stop_program
3. You use a lot of if var == False: which could be rewritten to if not var:
4. Same goes for if var == True: which is just if var:
5. You have some calculations like if val > 0 and val < 12: which can be rewritten to if 0 < val < 12:
6. When using comments don't indent them! - #comment should be # comment

---

Other improvements:

When possible use libraries, be sure to check out datetime library

Answer 2

I thought I'd have a go at this. I've done it in c# - yes I know it's a different language but hold on - you should be able to draw some useful general principles from it.

I've tried to make it more readable and implemented an OOP approach. Although I would have liked to make inroads in simplifying the actual algorithm which does the conversion, I think you'll probably see what I've done.

Make it readable

See the link attached - i'm hoping it is a little more readable - in terms of having small methods which do a particular job. IsValid(), IsDayValid() IsYearValid() etc are all small methods which do a particular and improve readability.

using System;
namespace ConsoleApplication1
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            // prints welcome
            // gets date input
            DateConverter dc = new DateConverter();

            dc.PrintConvertedDate();
            dc.PrintRepublicanDate();

            Console.ReadLine();
        }
    }

    public class DateConverter
    {
        public RepublicanDate republicDate { get; set; }

        public DateConverter()
        {
            PrintWelcome();
            this.republicDate = GetDate();
        }

        public void PrintWelcome()
        {
            Console.WriteLine("\nRepublican to Gregorian Date Converter");
            Console.WriteLine("\nThis program will convert a date from the French Republican Calendar to the equivalent date in the Gregorian Calendar.");
            Console.WriteLine("\nTo stop calculating dates and close the program, simply input: 0 0 0.\n");
        }

        public DateTime ConvertDate()
        {
            return republicDate.ConvertToGregorianDate();
        }

        public void PrintConvertedDate()
        {
            // prints converted date
            Console.WriteLine("This converted gregorian date is: " + this.ConvertDate());
        }

        public void PrintRepublicanDate()
        {
            // prints the republic date in its original string format.
            Console.WriteLine(republicDate.ToString());
        }

        private RepublicanDate GetDate()
        {
            RepublicanDate date;

            // repeat untill we get a valid date value
            do
            {
                date = new RepublicanDate();
            } while (date.IsInvalid());

            return date;
        }
    }

    public class RepublicanDate
    {
        private DayMonthYear input;

        public RepublicanDate()
        {
            input = GetInputDate();
        }

        private DayMonthYear GetInputDate()
        {
            Console.WriteLine("Input a Republican Date in the format: 'dd mm yy'. Please enter a republican date: \n");
            string date = Console.ReadLine();
            string[] dateArray = date.Split(' ');

            int day = int.Parse(dateArray[0]);
            int month = int.Parse(dateArray[1]);
            int year = int.Parse(dateArray[2]);

            DayMonthYear dt = new DayMonthYear(day, month, year);

            return dt;
        }

        #region Validity methods

        public bool IsInvalid()
        {
            if (IsYearInvalid(input))
            {
                return true;
            }
            else if (IsMonthInvalid(input))
            {
                return true;
            }
            else if (IsDayInvalid(input))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        private bool IsDayInvalid(DayMonthYear input)
        {
            if (input.Day >= 1 && input.Day <= 30)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private bool IsMonthInvalid(DayMonthYear input)
        {
            if (input.Month >= 1 && input.Month <= 12)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private bool IsYearInvalid(DayMonthYear input)
        {
            if (input.Year >= 1 && input.Year <= 14)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        #endregion Validity methods

        public override string ToString()
        {
            return String.Format("The french Rpublic Date is: {0} {1} and {2}", input.Day, GetFrenchMonth(input.Month), GetFrenchYear(input.Year));
        }

        #region To String Helper methods

        private string GetFrenchMonth(int monthNumber)
        {
            switch (monthNumber)
            {
                case 1:
                    return "Vendémiaire";

                case 2:
                    return "Brumaire";

                case 3:
                    return "Frimaire";

                case 4:
                    return "Nivôse";

                case 5:
                    return "Pluviôse";

                case 6:
                    return "Ventôse";

                case 7:
                    return "Germinal";

                case 8:
                    return "Floréal";

                case 9:
                    return "Prairial";

                case 10:
                    return "Messidor";

                case 11:
                    return "Thermidor";

                case 12:
                    return "Fructidor";

                default:
                    throw new ArgumentOutOfRangeException("\n The months should only be between 1 and 12");
            }
        }

        private string GetFrenchYear(int YearNumber)
        {
            switch (YearNumber)
            {
                case 1:
                    return "I";

                case 2:
                    return "II";

                case 3:
                    return "III";

                case 4:
                    return "IV";

                case 5:
                    return "V";

                case 6:
                    return "VI";

                case 7:
                    return "VII";

                case 8:
                    return "VIII";

                case 9:
                    return "IX";

                case 10:
                    return "X";

                case 11:
                    return "XI";

                case 12:
                    return "XII";

                case 13:
                    return "XIII";

                case 14:
                    return "XIV";

                default:
                    throw new ArgumentOutOfRangeException("\n The year should only be between 1 and 14");
            }
        }

        #endregion To String Helper methods

        public DateTime ConvertToGregorianDate()
        {
            // just returned a dummy value, but all your conversion logic could go here:
            return new DateTime();

            // I can't comment too much on the logic seeing i don't understand it
            // but it looks like  you can certain break it up
            // to make it more readable and understandable.

            // all the conversion logic should go here.
            //monthL = 30
            //StartDate = 266
            //StartYear = 1792
            //YDays = 365
            //LYDays = 366

            //Year = StartYear + (yearN - 1)
            //Day = ((monthN - 1) * monthL) + dayN
            //if Leap == True and Day >= 60:
            //  Day += 1

            //PH = StartDate + Day
            //if Leap == True:
            //  if PH > LYDays:
            //    Year += 1
            //    Day = PH - LYDays
            //  else:
            //    Day = PH
            //if Leap == False:
            //  if PH > YDays:
            //    Year += 1
            //    Day = PH - YDays
            //  else:
            //    Day = PH

            //if Leap == False:
            //  if Day >= 1 and Day <= 31:
            //      GregMonth = "January"
            //  if Day >= 32 and Day <= 59:
            //      Day -= 31
            //      GregMonth = "February"
            //  if Day >= 60 and Day <= 90:
            //      Day -= 59
            //      GregMonth = "March"
            //  if Day >= 91 and Day <= 120:
            //      Day -= 90
            //      GregMonth = "April"
            //  if Day >= 121 and Day <= 151:
            //      Day -= 120
            //      GregMonth = "May"
            //  if Day >= 152 and Day <= 181:
            //      Day -= 151
            //      GregMonth = "June"
            //  if Day >= 182 and Day <= 212:
            //      Day -= 181
            //      GregMonth = "July"
            //  if Day >= 213 and Day <= 243:
            //      Day -= 212
            //      GregMonth = "August"
            //  if Day >= 244 and Day <= 273:
            //      Day -= 243
            //      GregMonth = "September"
            //  if Day >= 274 and Day <= 304:
            //      Day -= 273
            //      GregMonth = "October"
            //  if Day >= 305 and Day <= 334:
            //      Day -= 304
            //      GregMonth = "November"
            //  if Day >= 335 and Day <= 365:
            //      Day -= 334
            //      GregMonth = "December"

            //if Leap == True:
            //  if Day >= 1 and Day <= 31:
            //      GregMonth = "January"
            //  if Day >= 32 and Day <= 60:
            //      Day -= 32
            //      GregMonth = "February"
            //  if Day >= 61 and Day <= 91:
            //      Day -= 60
            //      GregMonth = "March"
            //  if Day >= 92 and Day <= 121:
            //      Day -= 91
            //      GregMonth = "April"
            //  if Day >= 122 and Day <= 152:
            //      Day -= 121
            //      GregMonth = "May"
            //  if Day >= 153 and Day <= 182:
            //      Day -= 152
            //      GregMonth = "June"
            //  if Day >= 183 and Day <= 213:
            //      Day -= 182
            //      GregMonth = "July"
            //  if Day >= 214 and Day <= 244:
            //      Day -= 213
            //      GregMonth = "August"
            //  if Day >= 245 and Day <= 274:
            //      Day -= 244
            //      GregMonth = "September"
            //  if Day >= 275 and Day <= 305:
            //      Day -= 274
            //      GregMonth = "October"
            //  if Day >= 306 and Day <= 335:
            //      Day -= 305
            //      GregMonth = "November"
            //  if Day >= 336 and Day <= 366:
            //      Day -= 335
            //      GregMonth = "December"

            //Day = str(Day)
            //Year = str (Year)
            //GregDate = Day + " " + GregMonth + " " + Year
            //Day = int(Day)
            //Year = int(Year)
            //print("The Gregorian Date is: ", GregDate, "\n")
            //return(GregDate)
        }
    }

    public struct DayMonthYear
    {
        public int Day { get; set; }
        public int Month { get; set; }
        public int Year { get; set; }

        public DayMonthYear(int day, int month, int year)
            : this()
        {
            this.Day = day;
            this.Month = month;
            this.Year = year;
        }
    }
}