show observation that got lost in merge

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无人共我
无人共我 2021-01-29 06:42

Lets say I want to merge two different dataframes by the key of two columns.

Dataframe One has 70000 obs of 10 variables. Dataframe Two has 4500 obs of 5 variables.

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  •  醉梦人生
    2021-01-29 07:13

    I think you can use dplyr::anti_join for this. From its documentation:

    return all rows from x where there are not matching values in y, keeping just columns from x.

    You'd probably have to pass your data frame TWO as x.

    EDIT: as mentioned in the comments, the syntax for its by argument is different.

    Example:

    df1 <- data.frame(Name=c("a", "b", "c"),
                      Date1=c(1,2,3),
                      stringsAsFactors=FALSE)
    
    df2 <- data.frame(Name=c("a", "d"),
                      Date2=c(1,2),
                      stringsAsFactors=FALSE)
    
    > dplyr::anti_join(df2, df1, by=c("Name"="Name", "Date2"="Date1"))
      Name Date
    1    d    2
    

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