plotIndividualTimeProfile(): error when DataCombined is emtpy

[PavelBal]

myCombDat <- DataCombined$new()

plotIndividualTimeProfile(myCombDat)

Error in UseMethod("group_by") : 
no applicable method for 'group_by' applied to an object of class "NULL"
8.
dplyr::group_by(., {
{
unitColumn
} ...
7.
dplyr::tally(., name = "unitFrequency")
6.
data %>% dplyr::group_by({
{
unitColumn
} ... at utilities-units.R#693
5.
.extractMostFrequentUnit(data, unitColumn = "xUnit") at utilities-units.R#483
4.
xUnit %||% .extractMostFrequentUnit(data, unitColumn = "xUnit") at utilities-units.R#483
3.
.unitConverter(combinedData, defaultPlotConfiguration$xUnit, 
defaultPlotConfiguration$yUnit) at plot-individual-time-profile.R#41
2.
.plotTimeProfile(dataCombined, defaultPlotConfiguration) at plot-individual-time-profile.R#18
1.
plotIndividualTimeProfile(myCombDat)

Instead, it should produce an empty plot (and, if defined in the plot configuration, title subtitle and so on).

[IndrajeetPatil]

Instead, it should produce an empty plot (and, if defined in the plot configuration, title subtitle and so on).

But this is not something tlf can do. It doesn't return an empty plot; it returns NULL instead.

tlf::plotTimeProfile(
  data = data.frame(),
  observedDataMapping = tlf::ObservedDataMapping$new(
    x = "xValues",
    y = "yValues",
    group = "group",
    error = "yErrorValues"
  ),
  plotConfiguration = tlf::TimeProfilePlotConfiguration$new()
)
#> Warning in tlf::plotTimeProfile(data = data.frame(), observedDataMapping =
#> tlf::ObservedDataMapping$new(x = "xValues", : 'data' and 'observedData' are of
#> length 0. Time profile layer was not added.
#> NULL

^{Created on 2022-07-04 by the reprex package (v2.0.1.9000)}

Also, I am not sure if it makes sense to plot anything in such cases.
We should just issue a warning and return a NULL or an empty plot.

library(ggplot2)
ggplot()

^{Created on 2022-07-04 by the reprex package (v2.0.1.9000)}

[IndrajeetPatil]

I think this is the best solution because we are also being consistent with the underlying tlf function:

library(ospsuite)

myCombDat <- DataCombined$new()
plotIndividualTimeProfile(myCombDat)
#> Warning in .plotTimeProfile(dataCombined, defaultPlotConfiguration): No plot
#> can be created because the entered `DataCombined` object does not contain any
#> datasets.
#> NULL

^{Created on 2022-07-04 by the reprex package (v2.0.1.9000)}

[PavelBal]

That sounds reasonable.