Update dash_plotly_QC_scRNA.py

dash_plotly_QC_scRNA.py

@@ -1,7 +1,7 @@
 # Dash app to visualize scRNA-seq data quality control metrics from scanpy objects
 # Shoutout to Coding-with-Adam for the initial template of the project: 
 # https://github.com/Coding-with-Adam/Dash-by-Plotly/blob/master/Dash%20Components/Graph/dash-graph.py
-
+df=None
 import dash
 from dash import dcc, html, Output, Input
 import plotly.express as px