title: Merge csv to shp: return with DataFrame instead of GeoDataFrame
body: <p>I would like to join the table to shp and plot the Map out using Python. However, the merged DataFrame is no longer a GeoDataFrame... why??? Anyone can help please~~~</p>
  <pre class="lang-py prettyprint-override"><code># Important library for many geopython libraries
  !apt install gdal-bin python-gdal python3-gdal 
  # Install rtree - Geopandas requirment
  !apt install python3-rtree 
  # Install Geopandas
  !pip install git+git://github.com/geopandas/geopandas.git
  # Install descartes - Geopandas requirment
  !pip install descartes 
  # Install Folium for Geographic data visualization
  !pip install folium
  # Install plotlyExpress
  !pip install plotly_express
  
  # Import packages
  import pandas as pd
  import numpy as np
  import geopandas as gpd
  from shapely.geometry import Point
  import matplotlib
  import matplotlib.pyplot as plt 
  import folium
  import plotly_express as px
  
  
  file1 = 'GEO.shp'
  GEO = gpd.read_file(file1)
  
  file2 = 'data.csv'
  DATA = gpd.read_file(file2)
  
  Join = GEO.merge(DATA, left_on='Code', right_on='M_code')
  
  type(Join)
  
  ## Return --&gt; pandas.core.frame.DataFrame
  </code></pre>