title: R - Plotting a line with missing NA values
body: <p>I have the following data.frame, "subset"</p>
  
  <pre><code>Time            A   B   C
  2016-10-07 06:16:46 NA  NA  41 
  2016-10-07 06:26:27 40  39  42
  2016-10-07 06:38:23 NA  40  NA
  2016-10-07 06:41:06 42  42  44
  2016-10-07 06:41:06 NA  42  44
  2016-10-07 06:41:06 NA  42  44
  2016-10-07 06:41:07 44  43  48
  2016-10-07 06:41:41 NA  43  48
  2016-10-07 06:42:44 45  42  48
  2016-10-07 06:48:40 46  45  48
  </code></pre>
  
  <p>I would like to have a plot where "Time" is the x-axis, "A" is a line and "B" and "C" are points. </p>
  
  <p>However, when i plot this, the only line that appears for "A" is the one connecting the last 2 dots (45 and 46), because these are the only 2 consecutive values in "A". The plot ignores the NAs between the values of "A" instead of potting a line connecting these values through the NAs. To do so, I use the following code:</p>
  
  <pre><code>plot(subset$Time,subset$A,type="l",ylim=c(min(subset$B,na.rm=TRUE)-5,max(subset$C,na.rm=TRUE)+5),xlim=c(as.POSIXct(min(subset$Time)),as.POSIXct(max(subset$Time))))
  lines(subset$Time,subset$B,type="p",col=27)
  lines(subset$Time,subset$C,type="p",col=134)
  </code></pre>
  
  <p>I have tried solutions such as na.omit() or na.approx(), however these seem to work only if I would plot "A" separately in a stand-alone plot, they do not seem to work in conjunction with "Time" and "B" and "C" all in the same plot.</p>