# 7. Answers to common questions and extra examples

This vignette documents miscellaneous examples and questions received regarding the `cubble` package.

# Why summarising of temporal data by station is not in temporal form?

Q: I’m trying to summarise the average maximum temperature by station. I’m not sure why the summarise function is not returning a temporal object.

    climate_mel |>
      face_temporal() |>
      summarise(tmax_avg = mean(tmax, na.rm=TRUE))
    #> # A tibble: 3 × 2
    #>   id          tmax_avg
    #>   <chr>          <dbl>
    #> 1 ASN00086038     26.5
    #> 2 ASN00086077     25.7
    #> 3 ASN00086282     26.6

A: This operation should be performed in the spatial form. The form to use for an operation depends on the structure of the result. If the result has each key in a row without temporal index, it should be operated in the spatial form (example here):

    climate_mel |>
      rowwise() |>
      mutate(tmax_avg = mean(ts$tmax, na.rm=TRUE))
    #> # cubble:   key: id [3], index: date, nested form
    #> # spatial:  [144.83, -37.98, 145.1, -37.67], Missing CRS!
    #> # temporal: date [date], prcp [dbl], tmax [dbl], tmin [dbl]
    #>   id           long   lat  elev name              wmo_id ts       tmax_avg
    #>   <chr>       <dbl> <dbl> <dbl> <chr>              <dbl> <list>      <dbl>
    #> 1 ASN00086038  145. -37.7  78.4 essendon airport   95866 <tibble>     26.5
    #> 2 ASN00086077  145. -38.0  12.1 moorabbin airport  94870 <tibble>     25.7
    #> 3 ASN00086282  145. -37.7 113.  melbourne airport  94866 <tibble>     26.6