plot-schema axis regex doesn't include `x1`

[chriddyp]

In the new plotly.py PR (plotly/plotly.py#942), we're using the plot schema for validation. The current regex for axes keys is

"layout": {
    "layoutAttributes": {
        ...
        "xaxis": {
              "anchor": {
                    ...
                    "valType": "enumerated",
                    "values": [
                        "free",
                        "/^x([2-9]|[1-9][0-9]+)?$/",
                        "/^y([2-9]|[1-9][0-9]+)?$/"
                    ]
              },
         },
    },
}

which doesn't support x1. The plotly.py library uses x1 in make_subplots and other places as an alternative to x.

[alexcjohnson]

x1 is not really accepted by plotly.js - it's generally converted to x, though I wouldn't say with any confidence that every place you can use an axis reference will make this conversion. Likewise (and this I can say confidently) if you pass in a layout with xaxis1 it will be renamed to xaxis.

Would it be possible for plotly.py to force x instead of x1 as well, either by automatically converting like we do here or simply not accepting x1?

[etpinard]

Related: #2007

[etpinard]

I wouldn't be opposed to start to officially accept 'x1' axis id and 'xaxis1' axis names in plotly.js as long as we make it clear in our docs that 'x(axis)1' refers to the same axis as 'x(axis)'.

We'll need to clear up what happens when xaxis and xaxis1 are present in the layout. I'd say ignoring xaxis1 in that case would suffice. We should also make Plotly.validate log something whenever xaxis and xaxis1 are used in the same layout.

[gvwilson]

Hi - this issue has been sitting for a while, so as part of our effort to tidy up our public repositories I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our stack. Cheers - @gvwilson