Features Disappear on 'Apply' When Creating Training Samples in geemap Tutorial (nb 67)

[Gui-FernandesBR]

I'm trying to follow this tutorial to create training samples: https://geemap.org/notebooks/67_training_samples/

I'm following the very same steps, but when I click "apply", the current features just disappear. This makes impossible to draw several features, of different classes, and covert then to a single feature collection as suggested by the video.

I wonder if one of the following is happening:

1. I'm doing something wrong
2. The feature in the video is no longer supported
3. There's a bug in my environment (although I'm running on google colab...)
4. There's a bug within the lib

Expected behavior:
I want to see the different classes polygons altogether, like this:

Note 1: It is hard to me explain the issue because I'm not an expert on recording videos or gifs, but I gave it a try: https://drive.google.com/file/d/1GJq-FVKKqBjF46hEgPgf03dWPeO9CGXh/view?usp=sharing

Note 2: I could save the features class by class (i.e. all the polygon for water, then all the houses, etc.), using the my_map.user_rois multiple times. However, as I'm trying to use this for educational purposes, having the possibility of collecting all the features from different classes at the same time would be really important here. I'm trying to replicate the steps of js Code Editor on Python.

[Gui-FernandesBR]

I saw a comment in the video description after opening this discussion. It is a bit old tho, so I guess it is worth it the shot:

• is this still not supported on colab?
• I even tried in vscode first, but the result is the same.... Where exactly was the video recorded from? jupyterlab?
• Is there something we could do to add this kind of support in colab?

The comment:

[giswqs]

The draw control has some major changes recently. That might have caused this bug. For the time being, install an older version of geemap, such as pip install geemap==0.25.0. That should still work. I will look into this bug when I have time.

[Gui-FernandesBR]

I tested a few versions on google Collab...

• pip install geemap==0.25.0
• pip install geemap==0.24.0
• pip install geemap==0.19.0
• pip install geemap==0.15.0

None of them worked. So there's also the hypothesis that this problem is coming from some dependency (probably the ipyleaflet).

---

I decided to read the geemap source code on the latest version anyway. If my understanding is right, this code line should be problematic:

geemap/geemap/toolbar.py

Line 1896 in 7be18b3

m.remove_draw_control()

I don't see where or when the drawn polygons are being saved before calling the m.remove_draw_control() method.
Everytime the user hits "Apply", it delete the current draw_control with its drawn features and generates a new one. Keeping the current polygons is important, no?

---

Alternatively, I wonder if there's already a feature to allow me to first draw multiple polygons and then modify its properties, that would work even better for collecting training samples. it is like "draw the polygons first, label them later"

[giswqs]

This is a complicate issue that needs sometime to resolve. If you want to modify the drawn feature properties, you can use m._draw_control.data to access the GeoJSON features and turn them into GeoDataFrame, which should allow you to to modidy the properties.

[Gui-FernandesBR]

Hello Prof, any updates on this one?

I will be entering vacations by the end of this month so I would be willing to help solving the bug if I am able to.

Also, I wonder whether we should convert this discussion into an issue.

[giswqs]

Feel free to submit a pull request if have time to work on it.