[R] Extracting a subset from a dataframe

[Xiaohui]

Try: D1[setdiff(D1$dates,D2$dates) , ]

Xiaohui

Augusto.Sanabria at ga.gov.au wrote:
> Good day everyone,
>
> Can anyone suggest an effective method to solve
> the following problem:
>
> I have 2 dataframes D1 and D2 as follows:
>
> D1:
>         dates       ws   wc pwc
>  2005-10-19:12:00  10.8  80  81
>  2005-10-20:12:00  12.3   5  15
>  2005-10-21:15:00  12.3   3  15
>  2005-10-22:15:00  11.3  13  95
>  2005-10-23:12:00  12.3  13   2
>  2005-10-24:15:00  10.3   2  95
>  2005-10-25:15:00  10.3   2   2
>
> D2:
>         dates       ws   wc  pwc
>  2005-02-02:15:00  17.5   5  96
>  2005-02-19:15:00  20.1  15  97
>  2005-02-20:18:00  16.5  95  95
>  2005-03-03:18:00  10.3  95  95
>  2005-03-04:00:00  13.4  13  95
>  2005-10-22:15:00  11.3  13  95
>  2005-10-25:15:00  10.3   2   2
>
> I want to create another dataframe made up
> of the values of dataframe1 which are not common
> with dataframe2, ie. newD = D1 - (D1 intersection D2)
>
> that is,
> newD: 
>        dates        ws   wc  pwc
>  2005-10-19:12:00  10.8  80  81
>  2005-10-20:12:00  12.3   5  15
>  2005-10-21:15:00  12.3   3  15
>  2005-10-23:12:00  12.3  13   2
>  2005-10-24:15:00  10.3   2  95
>  
> Thanks for any help you can provide,
>
> Augusto
>
> --------------------------------------------
> Augusto Sanabria. MSc, PhD.
> Mathematical Modeller
> Risk Research Group
> Geospatial & Earth Monitoring Division
> Geoscience Australia (www.ga.gov.au)
> Cnr. Jerrabomberra Av. & Hindmarsh Dr.
> Symonston ACT 2601
> Ph. (02) 6249-9155
>
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> and provide commented, minimal, self-contained, reproducible code.
>
>