title: R: as.POSIXct returns NA
body: <p>I am new on manipulating time in R. I am trying to turn a character a="201304021500" into POSIXct form using the following code:</p>
  
  <pre><code>#First I turn my charcter a into the format "2013/04/02 15:00" 
  
      annee=substr(a,1,4)
      mois=substr(a,5,6)
      jour=substr(a,7,8)
      heure=substr(a,9,10)
      a=paste(paste(annee,mois,jour,sep="/"),paste(heure,min,sep=":"),sep=" ")
  
  #Then I use the as.POSIXct function (as follows) that unfortunately returns NA even though the date "2013/04/02 15:00" does not correspond to the time where #the DST was #changed in France (where I am working)
  
  &gt; as.POSIXct(a,format="%y/%m/%d %h:%m",tz="Europe/Paris")
  [1] NA
  </code></pre>
  
  <p>How can I solve this problem ? Much appreciated !</p>