title: How to ignore missing data in form of dots?
body: <p>this probably a very simple question but I am a very beginner in R programming so far.
  I have a data set of annual GDP growth rate for all African countries (54) in the period 1960-2020. There are missing data for some years and some countries but not in form of NA as usual but in form of dots (&quot;...&quot;). Of course, this makes all further calculations impossible.
  How could I either &quot;clean&quot; the data set from those missing values or maybe replace them by zero (&quot;O)?
  Thanks in advance!</p>