DateTime in Table causes trouble

[tamasgal]

I was plotting some date related datasets today and bumped into the issue with DateTime object. First I thought they are not supported but there the docs mention that both "Date and DateTime types are supported natively" (https://kristofferc.github.io/PGFPlotsX.jl/v1/examples/juliatypes/#Dates)

The example in the docs is

using Dates
dategrid = Date(2000,1,1):Day(1):Date(2000,12,31)
relative_irradiance(d) = (1 + 0.034*cospi(2*Dates.dayofyear(d)/365.25))

@pgf Axis(
    {
        date_coordinates_in = "x",
        x_tick_label_style = "{rotate=90}",
        xlabel = "date",
        ylabel = "relative solar irradiance",
    },
    Plot(
    {
        no_marks
    },
    Table(dategrid, relative_irradiance.(dategrid))))

...and when I replace Date with DateTime, I get the following error:

! Package PGF Math Error: Could not parse input '00:00' as a floating point num
ber, sorry. The unreadable part was near ':00'..

See the PGF Math package documentation for explanation.
Type  H <return>  for immediate help.
 ...      

Looking at the print_tex output reveals that the times appear in an additional column, which explains the error above:

\begin{axis}[date coordinates in={x}, x tick label style={{rotate=90}}, xlabel={date}, ylabel={relative solar irradiance}]
    \addplot[no marks]
        table[row sep={\\}]
        {
            \\
            2000-01-01 00:00  1.0339949694264963  \\
            2000-01-02 00:00  1.0339798791946129  \\
            2000-01-03 00:00  1.033954733769792  \\
            2000-01-04 00:00  1.0339195405929695  \\
            2000-01-05 00:00  1.0338743100783727  \\
...
...
...

I also tried defining column names in the Axis with

			x = "d",
			y = "i",

and then pass Table([:d => dategrid, :i => relative_irradiance.(dategrid)])

but this does not help since the second column has no name 😉

\begin{axis}[date coordinates in={x}, x={d}, y={i}, x tick label style={{rotate=90}}, xlabel={date}, ylabel={relative solar irradiance}]
    \addplot[no marks]
        table[row sep={\\}]
        {
            d  i  \\
            2000-01-01 00:00  1.0339949694264963  \\
            2000-01-02 00:00  1.0339798791946129  \\
            2000-01-03 00:00  1.033954733769792  \\
            2000-01-04 00:00  1.0339195405929695  \\
...
...
...

I also tried to use comma as separator with

	    PGFPlotsX.Plot(
	    {
	        no_marks,
			col_sep="comma"
	    },
	    Table({col_sep="comma"}, [:d => dategrid, :i => relative_irradiance.(dategrid)])))

but somehow it's ignored:

\begin{axis}[date coordinates in={x}, x={d}, y={i}, x tick label style={{rotate=90}}, xlabel={date}, ylabel={relative solar irradiance}]
    \addplot[no marks, col sep={comma}]
        table[row sep={\\}, col sep={comma}]
        {
            d  i  \\
            2000-01-01 00:00  1.0339949694264963  \\
            2000-01-02 00:00  1.0339798791946129  \\
            2000-01-03 00:00  1.033954733769792  \\
            2000-01-04 00:00  1.0339195405929695  \\

Any suggestions? Coordinates does not like dates...

[KristofferC]

Any suggestions?

I would think like this:

• How do we want the latex to look?
• Where is the current code that transform the DateTime to latex code
• Change that code to make it transform to the latex code we want to have.

[tamasgal]

I am not sure to be honest ;) I think the issue is two-fold:

1. com sep is ignored in Table (if that would work, we would have a workaround for this issue)
2. the actual issue that the default representation of DateTime is misinterpreted due to the same separator for the date/time and table columns

[tamasgal]

It seems to me that the only way to make this work is to either provide an extra column automagically when a table has a DateTime row, which is fairly implicit solution and may lead to surprises or to force the separator to be a comma, which is a breaking change 😕

I guess I'll first create a PR which adds the col sep functionality to Table and then maybe just live with a note in the docs that a DateTime needs a non-space separator.

[KristofferC]

Can't we just define a Date Time to latex method that formats it in the way we want?

[tamasgal]

I will check the PGF manual later but as far as I understood the time is space separated from the date. The examples I found used comma as a separator but Tables used space.

Maybe I overlooked something, I will investigate.