[R] Need to compare two columns in two data.frames and return all rows from df where rows values are missing

[Gregg Powell]

Thanks Dr. Michaels.


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Sunday, June 13th, 2021 at 4:17 PM, William Michels <wjm1 using caa.columbia.edu> wrote:

> Maybe something like this?
> 

> > df_A <- data.frame(names=LETTERS[1:10], values_A=1:10)
> > 

> > df_B <- data.frame(names=LETTERS[6:15], values_B=11:20)
> > 

> > df_AB <- merge(df_A, df_B, by="names")
> > 

> > df_AAB <- merge(df_A, df_AB, all.x=TRUE)
> > 

> > df_BAB <- merge(df_B, df_AB, all.x=TRUE)
> > 

> > df_C <- df_AAB[is.na(df_AAB$values_B), ]
> > 

> > df_D <- df_BAB[is.na(df_BAB$values_A), ]
> > 

> > df_AB
> 

> names values_A values_B
> 

> 1 F 6 11
> 

> 2 G 7 12
> 

> 3 H 8 13
> 

> 4 I 9 14
> 

> 5 J 10 15
> 

> > df_C
> 

> names values_A values_B
> 

> 1 A 1 NA
> 

> 2 B 2 NA
> 

> 3 C 3 NA
> 

> 4 D 4 NA
> 

> 5 E 5 NA
> 

> > df_D
> 

> names values_B values_A
> 

> 6 K 16 NA
> 

> 7 L 17 NA
> 

> 8 M 18 NA
> 

> 9 N 19 NA
> 

> 10 O 20 NA
> 

> HTH, Bill.
> 

> W. Michels, Ph.D.
> 

> On Sun, Jun 13, 2021 at 2:38 PM Gregg Powell via R-help
> 

> r-help using r-project.org wrote:
> 

> > This is even complicated to write into a question....
> > 

> > Have two data.frames (A and B)
> > 

> > data.frame A and B each have a name column. Want to compare A and B data.frame to each other based on the values in the 'names' columns - for every name that appears in dataframe A but not B, I want to copy the corresponding rows to a third dataframe C, and for every name that appears in B but not A, I want to copy the corresponding rows to a fourth dataframe D. I can then row bind the dataframes C and D together and get a complete list of all the rows that were missing in either A or B.
> > 

> > try as I might - I can't get this to work. Can someone help P-L-E-A-S-E!!!!
> > 

> > Thanks,
> > 

> > Gregg Powell
> > 

> > AZ, USA______________________________________________
> > 

> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > 

> > 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.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 509 bytes
Desc: OpenPGP digital signature
URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20210613/a3a9daa8/attachment.sig>