how to compare two columns with different number of row

Question

I have 2 large data frame that look:

  V1            Tri1    Tri2    Tri3    Tri4
200610-214      A G     A G     G G     G G
2010-08-Y       A G     A G     G G     G G
exm-IND22       I I     I I     I I     D D
exm-rs10223     A A     C C     C C     C C
exm-rs16933415  G G     A G     A A     A A
exm-rs2172802   A A     A A     A A     A G
exm-rs2284176   A A     A A     A A     A A
exm-rs2681019   A A     C C     A A     A A
exm-rs2853931   A A     A A     A A     A A
exm-rs3131786   C C     C C     C G     C C
exm-rs3177928   G G     G G     G G     G G
exm-rs7067387   A G     A G     A A     A A
exm-rs950063    G G     A A     G G     G G

and

V1          
200610-214      
2010-08-Y       
exm-rs10223    
exm-rs2172802   
exm-rs2681019   
exm-rs2853931   
exm-rs3131786

I want to find column of second data frame in first data frame and get new data frame that should look

V1              Tri1    Tri2    Tri3    Tri4
200610-214      A G     A G     G G     G G
2010-08-Y       A G     A G     G G     G G
exm-rs10223     A A     C C     C C     C C
exm-rs2172802   A A     A A     A A     A G
exm-rs2681019   A A     C C     A A     A A
exm-rs2853931   A A     A A     A A     A A
exm-rs3131786   C C     C C     C G     C C

How i can do it?

see `?merge` ... or the `*_join` functions in the `dplyr` package ... — Ben Bolker, Dec 20 '16 at 15:33
Not quite a duplicate, as using a merge would be overkill in this case. — Hong Ooi, Dec 20 '16 at 15:35

score 1 · Answer 1 · answered Dec 20 '16 at 15:34

1

While you can use a merge, in this case there's a much simpler solution:

df1[df1$V1 %in% df2$V1, ]

where df1 is your main dataset, and df2 is the dataset with the values you want to keep.

answered Dec 20 '16 at 15:34

Hong Ooi

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how to compare two columns with different number of row

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