fix: Avoid sphinx error "Code Execution failed:NameError: name 'format_locale' is not defined"

[dangotbanned]

Occurs during doc build, due to both variables being used without a defintion.

./doc/Lib/site-packages/sphinxext_altair/altairplot.py:261:
UserWarning: altair-plot: ./altair/doc/user_guide/customization.rst:826 Code Execution failed:
NameError: name 'format_locale' is not defined
  warnings.warn(message, stacklevel=1)

[dangotbanned]

Another option could be just to remove that .. altair-plot::, since the one after has valid code.

Localization
------------
The preferred format of numbers, dates, and currencies varies by language and locale.
Vega-Altair takes advantage of `D3's localization support`_ to make it easy to configure
the locale for your chart using the global ``alt.renderers.set_embed_options`` function.

.. altair-plot::
   :output: none

   import altair as alt
   alt.renderers.set_embed_options(format_locale=None, time_format_locale=None)

Here ``format_locale`` and ``time_format_locale`` may either be D3 format dictionaries,
or strings with the names of pre-defined locales. For example, here we use the
Italian locale (named ``it-IT``) for both currencies and dates:

.. altair-plot::
   :output: none

   import altair as alt
   from vega_datasets import data

   alt.renderers.set_embed_options(format_locale="it-IT", time_format_locale="it-IT")

   source = data.stocks.url
   chart = alt.Chart(source).mark_area().transform_filter('year(datum.date) == 2009').encode(
       x='date:T',
       y=alt.Y('price:Q', axis=alt.Axis(format="$.0f")),
       color='symbol:N'
   )
   chart

[mattijn]

I agree with your comment that it makes more sense to render it as a code-block and not as a sphinxext-altair altair-plot directive

[dangotbanned]

I agree with your comment that it makes more sense to render it as a code-block and not as a sphinxext-altair altair-plot directive

@mattijn I agree with you on that, but that wasn't what I meant 😄

I meant this change:

diff --git a/doc/user_guide/customization.rst b/doc/user_guide/customization.rst
index 77eaf707..9759669b 100644
--- a/doc/user_guide/customization.rst
+++ b/doc/user_guide/customization.rst
@@ -823,12 +823,6 @@ The preferred format of numbers, dates, and currencies varies by language and lo
 Vega-Altair takes advantage of `D3's localization support`_ to make it easy to configure
 the locale for your chart using the global ``alt.renderers.set_embed_options`` function.
 
-.. altair-plot::
-   :output: none
-
-   import altair as alt
-   alt.renderers.set_embed_options(format_locale=None, time_format_locale=None)
-
 Here ``format_locale`` and ``time_format_locale`` may either be D3 format dictionaries,
 or strings with the names of pre-defined locales. For example, here we use the
 Italian locale (named ``it-IT``) for both currencies and dates:

---

Another option could be just to remove that .. altair-plot::, since the one after has valid code.

This one has to repeat all of what was in the other anyway, but uses real arguments:

.. altair-plot:: # <------
   :output: none # <------

   import altair as alt # <------
   from vega_datasets import data

   alt.renderers.set_embed_options(format_locale="it-IT", time_format_locale="it-IT") # <------

   source = data.stocks.url
   chart = alt.Chart(source).mark_area().transform_filter('year(datum.date) == 2009').encode(
       x='date:T',
       y=alt.Y('price:Q', axis=alt.Axis(format="$.0f")),
       color='symbol:N'
   )
   chart

---

I don't think there's any information lost as a result vs actual

[mattijn]

Also good👍

[dangotbanned]

Also good👍

Thanks @mattijn should be ready to merge now

[mattijn]

Thanks for the PR!🥳