title: R-Convert calendar day to fiscal year week that counts a week from Sunday?
body: <p>I used week() and strftime() to convert day to week in R, but the functions set start day from Monday not Sunday, converting calendar year day to fiscal year week becomes off. 
  My fiscal year starts from October 1st, and 2017-10-01 has to be week 1. However, strftime() counts week from monday, week of'2017-10-01', which is sunday, subtracts '2017-9-30', which is saturday, becomes 0 instead of 1.    </p>
  
  <pre><code>&gt; as.numeric(strftime("2017-10-1", format = "%V"), format = "%V")-as.numeric(strftime("2017-9-30", format = "%V"))
  [1] 0
  </code></pre>
  
  <p>How can I convert calendar day to fiscal year week that counts a week from Sunday?</p>