Black Lives Matter. Please consider donating to Black Girls Code today. # Polar plot sector tick rotation labels, special case

Hi,
Iinstead of labels that mark 0 to 360 degrees, I’d like to have the labels mark 0 to 180 clockwise and 0 to -180 degrees counter clockwise. If this is not possible as an option, is there an option for custom labels? If so, could someone provide an example?

The use-case is a rotating radar that has a cable that prevents full 360 degree rotation. It can only traverse 180 degrees clockwise or counterclockwise.

thank you.
bob s.

@rschaefer

To get ticklabels ranging from -180 to 180 degrees, just update `fig.layout` as follows:

``````fig.update_layout(polar_angularaxis= dict(tickvals = [0, 45, 90, 135, 180, 225, 270, 315],
ticktext=['\$0^\\circ\$',  '\$45^\\circ\$', '\$90^\\circ\$', '\$135^\\circ\$',
'\$-180^\\circ\$', '\$-135^\\circ\$', '\$-90^\\circ\$', '\$-45^\\circ\$']))
``````

This makes `ticktext[k]` to be displayed at the `tickval[k]`, k=0, …

It workswith both barpolar and scatterpolar.

thank you !!!   An alternative would be `fig.update_polars(sector=[-180,180])`

1 Like

thank you !!!    It’s so nice using `sector`, but from this description

`````` sector
|          Sets angular span of this polar subplot with two angles
|          (in degrees). Sector are assumed to be spanned in the
|          counterclockwise direction with 0 corresponding to
|          rightmost limit of the polar subplot.
``````

I couldn’t deduce the role of `sector`.

@empet definitely agreed! Do you have a suggestion for how to more clearly document this? This is wrapped in PX with `range_theta` and there’s a small example here: https://plot.ly/python/polar-chart/#polar-chart-sector

We would absolutely welcome any PRs on these doc pages… just click on the “edit this page in Github” button in the top-right and let us know what would help I tried this example, and it worked using fig.update_polars(sector=[-180,180]), but I want clockwise positive, so when I reversed the parameters, fig.update_polars(sector=[180,-180]), the image blew up. Interesting. There’s probably a logical reason for this.

You can flip the direction like this: `fig.update_polars(sector=[-180,180], angularaxis=dict(direction="clockwise", rotation=0))`

perfect. thank you. I hate the 20 word minimum for replies.

Followup question.

I asked about plotly but I am using dash, because everything in plotly translates to dash but
plotly is simpler to demo.

Now, for dash, if I use 0 rotation I get a 90 degrees rotation
“angularaxis” : {
“rotation” : 0,
“direction” : “clockwise”}

But if f I use 90 for rotation, the dash plot looks like the plotly plot with 0 rotation.

What is going on?