QGIS Map Atlas referring to a Layout Elevation Profile item - How to refer to an item using its dislayname or id

Question

I am using the latest version of QGIS 3.34 and trying to dynamically edit and update properties for Elevation Profiles in QGIS Map Atlas Layouts.

I am hoping to update layer and display symbols and other settings for a number of Elevation Profiles (see Class documentation QgsLayoutItemElevationProfile items) in a Map Atlas Layout when moving from one atlas page to another, (for over a 100 pages per atlas).

In order to refer to each of the different elevation profile items to change their settings I have been trying to find a way to refer to the displayname or the id (manually set in item id of the Elevation Profile). It looks like this is accessed using displayname or id using the class QgsLayoutItem.

After extensive searching for what seems relatively new functionality I cannot find any python examples on the use and updating of an QgsLayoutItemElevationProfile

I have tried many attempts to establish the name of each Elevation Profile. I have tried using selectedLayoutItems from the class QgsLayout but it returns an object identifier that I cant work out how to use.

Any examples on how to refer to Elevation Profiles by qgslayoutitem displayname or id and to update their properties?

Answer 1

Without seeing how you create your layout and its items, it's hard to give an exact answer.

However, you can use the .displayName() method, but you must first rename the elevation profile in the layout.

You can loop through all the items and check their class and display name, like so:

p = QgsProject.instance()
manager = p.layoutManager()
layout = manager.layouts()[0]                  # adjust index accordingly
# or
# layout = manager.layoutByName('Layout 1')    # adjust name accordingly

items = layout.items()

elev_profile = None
for item in items:
    if isinstance(item, QgsLayoutItemElevationProfile) and item.displayName() == 'my elevation profile':
        elev_profile = item
        break

elev_profile
# >>> <qgis._core.QgsLayoutItemElevationProfile object at 0x00000163FE685C10>

Or by using list comprehension:

elev_profile = [item for item in items if isinstance(item, QgsLayoutItemElevationProfile) and item.displayName() == 'my elevation profile'][0]

elev_profile
# >>> <qgis._core.QgsLayoutItemElevationProfile object at 0x00000163FE685C10>

---

If you create the QgsLayoutItemElevationProfile using PyQGIS then you can assign an ID (and/or display name) directly:

elev_profile = QgsLayoutItemElevationProfile(layout)
elev_profile.setId('my elevation profile id')
elev_profile.setDisplayName('my elevation profile')