C#•2y ago

❔ how remove duplicates from string?

I have following method:

private IEnumerable<(string Title, string Date)> GetFormattedHolidays(CalendarDto calendarDto)
    {
        foreach (var holiday in calendarDto.Holidays)
        {
            foreach (var day in calendarDto.Days)
            {
                if (day.Holiday == holiday.Id.ToString())
                {
                    var date = day.Day?.ToString("dd MMMM", _context.Culture);

                    yield return ($"{holiday.Title}", $"{date}");
                }
            }
        }
    }

private IEnumerable<(string Title, string Date)> GetFormattedHolidays(CalendarDto calendarDto)
    {
        foreach (var holiday in calendarDto.Holidays)
        {
            foreach (var day in calendarDto.Days)
            {
                if (day.Holiday == holiday.Id.ToString())
                {
                    var date = day.Day?.ToString("dd MMMM", _context.Culture);

                    yield return ($"{holiday.Title}", $"{date}");
                }
            }
        }
    }

it returns: [ "01 january, 02 january, 03 january", "07 march, 08 march" ] but I need this: [ "01, 02, 03 january", "07, 08 march" ] how to do it?

18 Replies

Doombox•2y ago

you can try using a GroupBy statement to group them by the month then iterate each group to produce the string

SWEETPONYOP•2y ago

this is very inconvenient to do..

Doombox•2y ago

yup

SWEETPONYOP•2y ago

idk maybe regex

Doombox•2y ago

that's definitely more inconvenient var grouped = calendarDto.Days.GroupBy(x => x.Month); isn't that inconvenient working with it is slightly more work but not hugely so I assume holidays can span across months? if so that really would be the way to go, you could write a "simpler" solution if a single holiday was constrained to one month

SWEETPONYOP•2y ago

I will try, thank you

Pobiega•2y ago

100% the trick is to group them before converting stuff to strings

Angius•2y ago

Should be doable entirely with LINQ

SWEETPONYOP•2y ago

I don't think that we can group by month my objects:

internal record CalendarDto(
    List<DayDto> Days,
    short Year,
    List<HolidayDto> Holidays);

internal record DayDto(
    DateTime? Day,
    DateTime? From,
    string Type,
    string Holiday);

internal record HolidayDto(
    int Id,
    string Title);

internal record CalendarDto(
    List<DayDto> Days,
    short Year,
    List<HolidayDto> Holidays);

internal record DayDto(
    DateTime? Day,
    DateTime? From,
    string Type,
    string Holiday);

internal record HolidayDto(
    int Id,
    string Title);

hmmm

Doombox•2y ago

your DateTime will contain a month property you can use to group them by

Pobiega•2y ago

var grouped = data.Days
    .GroupBy(x => x.Day.Value.Month)
    .Select(x =>
        $"{string.Join(", ", x.Select(y => y.Day.Value.Day))} {CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(x.Key)}")
    .ToArray();

Console.WriteLine(string.Join("\n", grouped));

var grouped = data.Days
    .GroupBy(x => x.Day.Value.Month)
    .Select(x =>
        $"{string.Join(", ", x.Select(y => y.Day.Value.Day))} {CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(x.Key)}")
    .ToArray();

Console.WriteLine(string.Join("\n", grouped));

ez katka

1, 2, 3 January
6, 7, 8 March

1, 2, 3 January
6, 7, 8 March

SWEETPONYOP•2y ago

soo good, thanks I definitely have to learn how to write good linq queries may you give me some advices about linq? how to write good linq queries? (as yours)

Pobiega•2y ago

you need to really understand the power of Select really. thats like, 90% of it my thought process here was...

okay, lets group the days by month, then I need to separate the days (values) from the month (key) into a string. for the days, we just join them up (but days are not strings, so we "extract" the string we want with another select) for the month, we use CultureInfo to get the month name because our month key is an int

SWEETPONYOP•2y ago

oookey, I see! thanks for helping, I'll practice linq to write queries as good as you

Pobiega•2y ago

Select is often called Map in other languages. SelectMany is often called Bind

SWEETPONYOP•2y ago

ah it's like map and bind from haskell

Pobiega•2y ago

yes

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ how remove duplicates from string?