enable formatting numbers with natural language suffixes, k(ilo), M(illion), B(illion)

Plotly doesn't currently let me format numbers, e.g. in hover templates, in "human" or "business" form, by which I mean essentially SI representation but with the suffix replacements k->k(ilo) M->M(illion), G->B(illion), T->T(trillion),.... (by pure luck, this is really just one necessary replacement in the range I've listed).

The reason seems to be that plotly relies on d3-format, which claims to "format numbers for human consumption" but misses the one format non-technically trained humans can actually consume at ease.

However, oddly plotly does use the "human readable" form by default for the X and Y columns in default hover displays, even when they're included in the hover templates manually as %{y}, but not for custom data included via %{customdata[0]} (see the MWE below). This in some sense makes this a bug: You want to include two columns of data in the same way, using the same format specifier, but you get different results.

Instead of waiting on d3, I would like to make this feature request: I believe plotly should default for custom data to the same formatting it uses by default elsewhere (including axes labels), unless a format specifier is explicitly listed, thus increasing consistency.

Example: Despite using text=y and hovertemplate ='%{y}<br>%{text}', I get different representations:

import plotly.graph_objects as go
y = [2, 100000, 2000000, 2000000000]
fig = go.Figure(go.Scatter(
    x = [1,2,3,4],
    y = y,
    text = y,
    hovertemplate ='%{y}<br>%{text}'
))
fig.show()

Similar requests elsewhere:
https://github.com/plotly/plotly.py/issues/1222

https://stackoverflow.com/questions/68005050/b-billions-instead-of-g-giga-in-python-plotly-customdata-si-prefix-d3

https://stackoverflow.com/questions/17037023/how-to-get-localizable-or-customizable-si-codes-with-d3-format

https://community.plotly.com/t/custom-si-unit-prefixes/29739/4

https://stackoverflow.com/questions/40774677/d3-formatting-tick-value-to-show-b-billion-instead-of-g-giga

https://github.com/d3/d3/issues/2241

https://stackoverflow.com/questions/64313173/how-to-hover-number-formatting-to-k-or-m-accordingly-in-r-plotly-pie-charts-and

https://github.com/d3/d3-format/issues/71

https://github.com/d3/d3-format/pull/81

https://github.com/d3/d3-format/pull/96

首先跟踪 hovertemplate 的值（尤其是 %{y}、%{text} 和 %{customdata[0]}）是如何格式化的，以及 d3-format 如何用于坐标轴和默认 hover。将现有行为与示例进行比较，然后定义测试，以表明自定义数据会遵循默认格式，除非提供了显式的格式说明符，同时包括所请求的自然语言后缀。