Altair: 12-hour clock

[Adrast]

Is there a way to change the 12-hour clock to a 24-hour clock as seen on the picture?

[Alcampopiano]

In your x channel you could use one of the D3 time formatting strings listed here.

For example

.
.
.
x=alt.X('Date:T', axis=alt.Axis(format='%H'))

[ejain]

By setting a fixed formatting string you lose the ability to have the tick labels be smart and include dates among the times (as shown in the picture above).