Q:

Merge data frames of unequal number of rows

I want to create a new data frame df3 from data frames df1 and df2. The dataframes contain zipcodes and states. One data frame has more zipcodes than the other. I want combine them and add NA for Zipcodes that do not have a value for the corresponding Zip code in the other file.
df3  
ZIP STATE   Total2 Total1  
36541   AL  6747   11190  
36542   AL  8093   10647  
36549   AL  9404   NA  
36551   AL  7048   10656  
36561   AL  5104   5044  
.
.
.

df1  
ZIP STATE   Total1  
36541   AL  11190  
36542   AL  10647  
36551   AL  10656  
36561   AL  5044  
32314   FL  10624  
32320   FL  5705  
32322   FL  11457  
32324   FL  5926  
32508   FL  8885  
32511   FL  9428  
32514   FL  6168  
32526   FL  11998  
32533   FL  11188  
32534   FL  11188  

df2  
ZIP STATE   Total2  
36541   AL  6747  
36542   AL  8093  
36549   AL  9404  
36551   AL  7048  
36561   AL  5104  
32314   FL  8959  
32320   FL  9237  
32321   FL  11417  
32322   FL  5467  
32324   FL  6672  
32508   FL  6085  
32511   FL  8782  
32514   FL  11297  
32522   FL  6892  
32526   FL  9497  
32533   FL  9114  
32534   FL  8594  

A:

merge() should do it:
merge(df1, df2, all=T)

