Get the first day of the week and the weekend

Question

I am working on a weekly teaching plan. I need the start date and end date of each week. For example, week 30 I want 7/25 - 7/29, week 31 I want 1/8 - 5/8. I don't want to do this manually, because it takes a long time. Is there a convenient way to get the first and last day of a week? Thank you.

Answer 1

Specifying the first day of the first week manually

You can use pgfcalendar to store the first day of your first week in a LaTeX counter and use that later as the base for an offset.

With \setStartDate you set the first day of your first week and the \getDateOfWeek{<week>}{<offset>} will define \Year, \Month, \Day with the date that is in the <week>th week with an additional <offset>.

For example:

\setStartDate{2022-10-10}

sets the first week to start on October 10th, 2022.

With

\getDateOfWeek{1}{4}

you'll get October 14th and with

\getDateOfWeek{2}{0}

you'll get October 17th in \Month and \Day.

Code

\documentclass{article}
\usepackage{pgfcalendar}
\newcounter{myStartDate}
\makeatletter
\newcommand*{\setStartDate}[1]{% for week 1
  \begingroup
    \pgfcalendardatetojulian{#1}{\@tempcnta}%
    \setcounter{myStartDate}{\@tempcnta}%
  \endgroup
}
\newcommand*{\getDateOfWeek}[2]{%
  \begingroup
    \@tempcnta=\inteval{(#1-1)*7+#2}\relax
    \advance\@tempcnta by \c@myStartDate
    \edef\@temp{\endgroup\noexpand\pgfcalendarjuliantodate{\the\@tempcnta}}%
    \@temp{\Year}{\Month}{\Day}%
}
\makeatother
\usepackage{pgffor}
\begin{document}
\setStartDate{2022-01-03}
\foreach \week in {1,...,52}{
  Week \week\ goes from \getDateOfWeek{\week}{0}\Month/\Day\ to
                        \getDateOfWeek{\week}{4}\Month/\Day.\par}
\end{document}

Output

Using the actual week numbers of the years.

With the pgfcalendar-ext package of my tikz-ext package which incorporates another answer of mine and uses the week numbering according to ISO 8601 which mainly means that a new week starts on Monday.

Here's a solution with

\getTwoDaysOfWeek[<year>]{<week>}{<offset>}
  {<year>}{<month>}{<day>}{<offset year>}{<offset month>}{<offset day>}

which defines six macros (the argments on the second line) for you which contain

• the first day of <week> of <year> and
• the day that's <offset> after the first day of <week> of <year>.

The <year> argument is optionally, the default is the current year.

Code

\documentclass{article}
\usepackage{pgfcalendar-ext}
\newcommand*{\stripZero}[1]{\if0#1\else#1\fi}
\makeatletter
\newcommand*{\getTwoDaysOfWeek}[9][\the\year]{%
  % #1 = year (defaults to current year)
  % #2 = week number, #3 = offset
  % #4/#5/#6 = start year/month/day
  % #7/#8/#9 = end year/month/day
  \begingroup
    \pgfcalendardatetojulian{#1-01-01}{\@tempcnta}%
    \pgfcalendarjuliantoweekday{\@tempcnta}{\@tempcntb}%
    \edef\@dateStartWeek{\the\numexpr\@tempcnta-\@tempcntb+#2*7-7\relax}%
    \pgfcalendarjulianyeartoweek{\@tempcnta}{#1}{\@tempcntb}%
    \ifnum\@tempcntb>1
      % This is the last week of the previous year
      \edef\@dateStartWeek{\the\numexpr\@dateStartWeek+7\relax}%
    \fi
    \edef\@temp{\endgroup%
      \noexpand\pgfcalendarjuliantodate
        {\@dateStartWeek}{\noexpand#4}{\noexpand#5}{\noexpand#6}%
      \noexpand\pgfcalendarjuliantodate
        {\the\numexpr\@dateStartWeek+#3\relax}{\noexpand#7}{\noexpand#8}{\noexpand#9}}%
  \@temp
}
\makeatother
\newcommand*{\weekCell}[2][\the\year]{%
  \begin{tabular}[t]{@{}l@{}}Week #2:\\
    \getTwoDaysOfWeek[#1]{#2}{4}{\y}{\m}{\d}{\Y}{\M}{\D}%
    \stripZero\m/\stripZero\d--\stripZero\M/\stripZero\D
  \end{tabular}}
\usepackage{pgffor}
\usepackage{booktabs}
\begin{document}
\begin{tabular}{lll}
\toprule
Time & Content & Note \\midrule
\weekCell{1} & Content 1 & Note 1 \
\weekCell{2} & Content 2 & Note 2 \
\dots & \dots & \dots \\bottomrule
\end{tabular}
\end{document}

Output