CODEWITHSUNDEEP
pythonbokeh
olivier dadoun
olivier dadoun

Reputation: 743

Label text position in Bokeh

I would like to stick MyText Label to the bottom right part of my figure for a given text and a given font size (as shown on the picture for 'this is super fun', font size of '20px' and with tiny characters. I found the good position by dichotomy ). What is the function position I need to pass to x ? This should depends on len(MyText), text_font_size and figure width ...

from bokeh.models import ColumnDataSource, Label, LabelSet, Range1d
from bokeh.plotting import figure, output_file, show
width,height=400,300
p = figure(plot_width=width, plot_height=height)
MyText='this is super fun'
my_font_size = "20px"
labels = Label(x=width/2+25, y=0,x_units='screen', y_units='screen', text=MyText,text_font_size=my_font_size)
p.add_layout(labels)
show(p)

bottom right position

Upvotes: 2

Views: 2702

Answers (1)

bigreddot
bigreddot

Reputation: 34568

I don't think there is any 100% robust way to do this, actually.

You can set the text_align to "right" which helps:

p = figure(plot_width=width, plot_height=height)
labels = Label(x=width-50, y=0, 
               x_units="screen", y_units='screen', text_align="right", 
               text=MyText,text_font_size=my_font_size)

Note the -50 above is to account (roughly) for the width of the space to the right of the "plot area" (i.e where the toolbar is). However if you add a y-axis on the left side, you'd need to account for that too, and if you allow zooming, then left space can grow and shrink to accommodate bigger or smaller axis labels, which means you can't reliably account for that space with a single constant up front. You could set min_border values to be larger, which might mitigate the problem for some range of zooming/panning.

Also the above assumes the plot sizing mode is not "responsive". If the plot itself can resize then no constant value in screen units will ever work.

If you can fix your x range start/end (or add an "extra" range), then you could right-align to the range end value using "data" units. But if you allow zooming or panning then the label will move to stay fixed at that data position.

The main issue is that the "inner_width" is only computed in the browser. It's not available to the Python code because it doesn't exist outside the browser. What's really needed is some special convention or confguration to designate "inner_width" as a symbolic concept that updates to whatever is necessary, regardless of panning or zooming or resizing. I'd suggest making a GitHub issue to propose this feature.

In the mean time, I think any solution will involve some trial and error with a fixed font size in "px" and also ideally limiting panning/zooming if possible.

Upvotes: 5

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