title: How tot get back from numpy datetime array to datetime?
body: <p>tried to write a simple programme for get the most vacation between two dates. E.g. for 2021, if wednesday is public holiday, you could get 9 free days with taking 4 holidays.</p>
  <p>..everything okay, my idea was:</p>
  <p>create busdaycalender, start, end, arange it and count all free days in a bool array and return the days.</p>
  <p>Now my problem:</p>
  <p>How could i get back the format for datetime?!I wanted to substract day2 from day1 (if day2-day1 &gt; 1 and &lt; 5 there is a holiday in between)
  I tried to convert all &quot;-&quot; in &quot;,&quot;, but the problem ist the zero at 2021-08-11 in front of e.g. the 8.
  Here's my code. Maybe someone has an idea.
  thanks !!</p>
  <pre><code>import numpy as np
  import datetime as dt
  
  start = dt.date( 2021, 1, 1 )
  end = dt.date(2021,12,31)
  
  
  bdd = np.busdaycalendar(weekmask='1111100',
              holidays=['2021-01-01', # 1.Januar
                        '2021-01-06', # 3 Könige
                        '2021-04-02', # Karfreitag
                        '2021-04-13', # Ostermontag
                        '2021-05-01', # Tag der Arbeit
                        '2021-05-21', # Vatertag
                        '2021-06-01', # Pfingstmontag
                        '2021-06-11', # Fronleichnam
                        '2021-10-03', # Tag der deutschen Einheit
                        '2021-11-01', # Allerheiligen
                        '2021-12-25', # 1. Weihnachtsfeiertag
                        '2021-12-25']) # 2.Weihnachtsfeiertag
  #print(bdd.holidays)
  
  days = np.busday_count(start, end, busdaycal=bdd)
  #print(days)
  alldays = np.arange('2020-12-31', '2022-01-01', dtype='datetime64[D]')
  #print(alldays)
  
  def count_urlaub2(numbers):
      results = []
      tage = []
      counter = 0
      for number in numbers:
          if np.is_busday(number, busdaycal=bdd) == bool(False):
              counter += 1
              tage.append(np.datetime_as_string(number, timezone='UTC'))
          elif (np.is_busday(number, busdaycal=bdd) == bool(True)) and counter:
              counter = 0
      return tage
  
  neueliste=[]
  for i in count_urlaub2(alldays):
      a = i.replace(&quot;-&quot;,&quot;,&quot;)
      neueliste.append(repr(a))
  print(neueliste)
  
  positionen = []
  for k in neueliste:
      for l in neueliste[1:]:
          erg = dt.date(l) - dt.date(k)
          if erg.days &gt; 1:
              positionen.append(blabla.index(k))
              print(&quot;evtl Urlaub nehmen&quot;)
  
  </code></pre>