title: How to join data from 2 different csv-files in R?
body: <p>I have the following problem: in a csv-file I have a column for species, one for transect, one for the year and one for the AUC. In another csv-file I have a column for transect, one for the year, one for precipitation and one for temperature. Now I would like to join the files in R in a way, that I can have the columns for species and AUC from the second csv and the columns for the rest from the first csv.
  In the end I'd like to get a file with transect_id, year, day, month, species, regional_gam(=AUC), precipitation and LST(=temperature). 
  So basically the precipitation-/ LST-values from TR001 for every day in 2008 need to be assigned to every species which has an AUC-value for 2008 and TR001.
  Thanks!</p>