Is it possible to change number format to scientific in QGIS layer legend?

Question

I have a layer with really small values and the classes in the legend do not look nice both for work in QGIS but also in the print layout.

Is it possible to somehow change the format of the numbers in the layer legend so instead numbers like:

0.000012345

I could get scientific notation:

1.2345e-5

or do I have to manually convert the numbers from the legend somewhere "outside" - maybe in some online tool like this and then paste it back in the legend as class label?

I googled and also looked in the QGIS documentation but did not find any solution.

Answer 1

For now, I think it's not possible in the layer properties.

But you can do something with the legend item in your layout by adding an expression to the vector layer and each child symbol's label with an expression like this :

    array_to_string(
    array_foreach(
    --split with dash
    string_to_array( @symbol_label,'-'),
    to_real(
    --replace comma by point (useful for french like me)
    replace(@element,',','.'))),' - ')

Documentation :

https://docs.qgis.org/3.16/en/docs/user_manual/print_composer/composer_items/composer_legend.html#data-define-the-legend-labels

Example :