Create a dictionary that contains all subzones as a keys and the list of their neighbors as the values using the following code dict = {} for i in range(len(df_spatial_melt)): zone = df_spatial_melt.iloc[i,0] if zone not in dict: dict[zone] = [] dict[zone].append(df_spatial_melt.iloc[i,1]) else: dict[zone].append(df_spatial_melt.iloc[i,1])