I have a large amount of Data where I have to count meassurments per one ID. What I already did was creating a Data Frame over all Files and I omited the NAs. This part works properly. I was wondering if the nrow-function is the right function to solve this but I figured out that this will not lead me to the target as it returns a single number as output.
What I am looking for is if you have entries like that:
1155 2010-05-02 2.7200 1 1156 2010-05-05 2.6000 3 1157 2010-05-08 2.6700 1 1158 2010-05-11 3.5700 2
That I get a list:
ID Number of observations 1 2 2 1 3 1