geodataframe is not defined

I’m working with Jupiter and ipywidgets and Ipyleaflet , trying to draw polygons on a map and saving to a geodataframe. I have the following in a notebook cell:

zoom = 15

from ipywidgets import Output, interact
import ipywidgets
from __future__ import print_function
import ipyleaflet
import geopandas as gpd
import pandas as pd

# from shapely.geometry import Point, LineString, Polygon
from shapely import geometry


from ipyleaflet import (
    Map,
    Marker,
    TileLayer, ImageOverlay,
    Polyline, Polygon, Rectangle, Circle, CircleMarker,
    GeoJSON,
    DrawControl)

# Create an Output widget
out = Output()

# Define a function to handle interactions
def handle_interaction(change):
    with out:
        print(change)


c = ipywidgets.Box()
c.children = [m]

# keep track of rectangles and polygons drawn on map:
def clear_m():
    global rects,polys
    rects = set()
    polys = set()

clear_m()
rect_color = '#a52a2a'
poly_color = '#00F'

myDrawControl = DrawControl(
rectangle={'shapeOptions':{'color':rect_color}},
        polygon={'shapeOptions':{'color':poly_color}}) #,polyline=None)

def handle_draw(self, action, geo_json):
    global rects,polys
    polygon=[]
    for coords in geo_json['geometry']['coordinates'][0][:-1][:]:
        handle_interaction(coords)
        polygon.append(tuple(coords))
    polygon = tuple(polygon)
    handle_interaction(polygon)
    if geo_json['properties']['style']['color'] == '#00F':  # poly
        if action == 'created':
            handle_interaction(" in here")
            polys.add(polygon)
            polygon_geom = geometry.Polygon(polygon)
    
            # Create GeoDataFrame if it doesn't exist
            if gdf2: is None:
                gdf2 = gpd.GeoDataFrame(geometry=[polygon_geom])
            else:
                gdf2 = gdf2.append({'geometry': polygon_geom}, ignore_index=True)
            
        elif action == 'deleted':
            polys.discard(polygon)
    if geo_json['properties']['style']['color'] == '#a52a2a':  # rect
        if action == 'created':
            rects.add(polygon)
        elif action == 'deleted':
            rects.discard(polygon)
myDrawControl.on_draw(handle_draw)
m.add_control(myDrawControl)

After drawing the shapes in the map, I can see

display(out)

[-88.434269, 31.660818]
[-88.431051, 31.661439]
[-88.431265, 31.660087]
[-88.433582, 31.659941]
((-88.434269, 31.660818), (-88.431051, 31.661439), (-88.431265, 31.660087), (-88.433582, 31.659941))
in here
[-88.432166, 31.658474]
[-88.429678, 31.65767]
[-88.431609, 31.656684]
[-88.434054, 31.65778]
((-88.432166, 31.658474), (-88.429678, 31.65767), (-88.431609, 31.656684), (-88.434054, 31.65778))
in here

listed in the next cell (the expected results). However when I try:

print(gdf2)

I get:

NameError: name 'gdf2' is not defined

What am I doing wrong

>Solution :

first of all, you wrote: if gdf2: is None:

Have you tried removing the : after gdf2 in the above condition?

Second: gdf2 is a local variable from handle_draw function. It is thus not defined outside of this function.

If you want to keep its value, define it before, e.g.

zoom = 15
gdf2 = None 

Then use global at the beginning of handle_draw function:

def handle_draw(self, action, geo_json):
    global gdf2