Fix emissions reporting bug in DB_to_Excel.py.

Temoa throws an error when trying to report emissions data
in the excel file when there are no emissions in the model
results. This commit patches the bug by first making sure
the there are emissions to report.

data_processing/DB_to_Excel.py

@@ -7,10 +7,10 @@
 from pyam import IamDataFrame
 
 def make_excel(ifile, ofile, scenario):
-	
+
 	if ifile is None :
 		raise "You did not specify the input file, remember to use '-i' option"
-		print("Use as :\n	python DB_to_Excel.py -i <input_file> (Optional -o <output_excel_file_name_only>)\n	Use -h for help.")                          
+		print("Use as :\n	python DB_to_Excel.py -i <input_file> (Optional -o <output_excel_file_name_only>)\n	Use -h for help.")
 		sys.exit(2)
 	else :
 		file_type = re.search(r"(\w+)\.(\w+)\b", ifile) # Extract the input filename and extension
@@ -75,18 +75,19 @@ def make_excel(ifile, ofile, scenario):
 	query = "SELECT regions, tech, sector, t_periods, emissions_comm, sum(emissions) as emissions FROM Output_Emissions WHERE scenario='" + scenario + "' GROUP BY \
 	regions, tech, sector, t_periods, emissions_comm"
 	df_emissions_raw = pd.read_sql_query(query, con)
-	df_emissions = df_emissions_raw.pivot_table(values='emissions', index=['regions', 'tech', 'sector','emissions_comm'], columns='t_periods')
-	df_emissions.reset_index(inplace=True)
-	df_emissions = pd.merge(all_emis_techs, df_emissions, on=['regions','tech', 'sector', 'emissions_comm'], how='left')
-	df_emissions.rename(columns={'regions':'Region', 'tech':'Technology', 'emissions_comm':'Emission Commodity', 'sector':'Sector'}, inplace=True)
-	df_emissions.to_excel(writer, sheet_name='Emissions', index=False, encoding='utf-8', startrow=1, header=False)
-	worksheet = writer.sheets['Emissions']
-	worksheet.set_column('A:A', 10)
-	worksheet.set_column('B:B', 10)
-	worksheet.set_column('C:C', 10)
-	worksheet.set_column('D:D', 20)
-	for col, val in enumerate(df_emissions.columns.values):
-		worksheet.write(0, col, val, header_format)
+	if not df_emissions_raw.empty:
+		df_emissions = df_emissions_raw.pivot_table(values='emissions', index=['regions', 'tech', 'sector','emissions_comm'], columns='t_periods')
+		df_emissions.reset_index(inplace=True)
+		df_emissions = pd.merge(all_emis_techs, df_emissions, on=['regions','tech', 'sector', 'emissions_comm'], how='left')
+		df_emissions.rename(columns={'regions':'Region', 'tech':'Technology', 'emissions_comm':'Emission Commodity', 'sector':'Sector'}, inplace=True)
+		df_emissions.to_excel(writer, sheet_name='Emissions', index=False, encoding='utf-8', startrow=1, header=False)
+		worksheet = writer.sheets['Emissions']
+		worksheet.set_column('A:A', 10)
+		worksheet.set_column('B:B', 10)
+		worksheet.set_column('C:C', 10)
+		worksheet.set_column('D:D', 20)
+		for col, val in enumerate(df_emissions.columns.values):
+			worksheet.write(0, col, val, header_format)
 
 	query = "SELECT regions, tech, sector, output_name,  vintage, output_cost FROM Output_Costs WHERE output_name LIKE '%V_Discounted%' AND scenario='" + scenario + "'"
 	df_costs = pd.read_sql_query(query, con)
@@ -118,7 +119,7 @@ def make_excel(ifile, ofile, scenario):
 	df_activity['variable']='Activity|' + df_activity['sector'] +  '|' + df_activity['tech']
 	df_activity.rename(columns={'t_periods':'year', 'vflow_out':'value', 'regions':'region'}, inplace=True)
 
-	
+
 	# cast results to IamDataFrame and write to xlsx
 	columns = ['scenario', 'region', 'variable', 'year', 'value', 'unit']
 	_results = pd.concat([df_emissions_raw[columns], df_activity[columns], df_capacity[columns]])
@@ -147,10 +148,10 @@ def get_data(inputs):
 	ifile = None
 	ofile = None
 	scenario = set()
-	
+
 	if inputs is None:
 		raise "no arguments found"
-		
+
 	for opt, arg in inputs.items():
 		if opt in ("-i", "--input"):
 			ifile = arg
@@ -159,20 +160,20 @@ def get_data(inputs):
 		elif opt in ("-s", "--scenario"):
 			scenario.add(arg)
 		elif opt in ("-h", "--help") :
-			print("Use as :\n	python DB_to_Excel.py -i <input_file> (Optional -o <output_excel_file_name_only>)\n	Use -h for help.")                         
+			print("Use as :\n	python DB_to_Excel.py -i <input_file> (Optional -o <output_excel_file_name_only>)\n	Use -h for help.")
 			sys.exit()
-		
+
 	make_excel(ifile, ofile, scenario)
 
-if __name__ == "__main__":	
-	
+if __name__ == "__main__":
+
 	try:
 		argv = sys.argv[1:]
 		opts, args = getopt.getopt(argv, "hi:o:s:", ["help", "input=", "output=", "scenario="])
-	except getopt.GetoptError:          
-		print("Something's Wrong. Use as :\n	python DB_to_Excel.py -i <input_file> (Optional -o <output_excel_file_name_only>)\n	Use -h for help.")                          
-		sys.exit(2) 
-		
+	except getopt.GetoptError:
+		print("Something's Wrong. Use as :\n	python DB_to_Excel.py -i <input_file> (Optional -o <output_excel_file_name_only>)\n	Use -h for help.")
+		sys.exit(2)
+
 	print(opts)
-		
-	get_data( dict(opts) )
+
+	get_data( dict(opts) )