首先计算具有多行的 Dataframe 。接下来，用NA值填充小于最大行数的 Dataframe ，在sapply中，我还扩展...
Up till now we have been looking at simple, separate column merges where you rely on columns being in the same order. For more complicated joins with multiple rows, multiple columns, and a different column value, take a look at our article aboutmerging dataframes. Related Topics & Alternative...