Thank you Petr! I have read on the merge help page, but I cant figure out how to write this function. When I use your function it includes all data from "data3", but all columns in "data" has "NA"(without "name" and "date". I hoped to keep these values to. I try to explain it more precise: In "data" with 14000 observations about company name, date, size of dividend etc. In "data3" there are 800000 daily observations of the stockprices for each company listed:
name date div statoil 17.05.2000 5 statoil 18.05.2001 6 ........ .............. ... Yara 17.05.2000 10 etc I want to get the stockprice for statoil, yara etc from "data3", and merge it into a new data like this: name date div price statoil 17.05.2000 5 120 statoil 18.05.2001 6 130 ........ .............. ... Yara 17.05.2000 10 200 etc And also keep the rest of the columns from both datasets. name date div price industry secid etc statoil 17.05.2000 5 120 ....... ..... ... statoil 18.05.2001 6 130 ....... ...... .... ........ .............. ... Yara 17.05.2000 10 200 ..... ...... ... etc Using the first function i get this result: name date div price industry secid etc statoil 17.05.2000 NA 120 ....... ..... ... statoil 18.05.2001 NA 130 ....... ...... .... ........ .............. ... Yara 17.05.2000 NA 200 ..... ...... ... Hope you understand what i want to do. Thanks again, I really appreciate it! etc -- View this message in context: http://r.789695.n4.nabble.com/merging-two-dataframes-tp3932869p3933101.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.