Add custom export functionality in app.py: introduce options to add all or selected rows from the merge DataFrame to the custom export, enhancing user control over data selection and improving export flexibility.

app.py

@@ -1205,10 +1205,18 @@ with tab2:
                 with download_port:
                     st.download_button(label="Download Portfolio", data=st.session_state['export_file'].to_csv(index=False), file_name="portfolio.csv", mime="text/csv")
                 with merge_port:
-                    if st.button("Add to Custom Export"):
-                        st.session_state['export_base'] = pd.concat([st.session_state['export_base'], st.session_state['export_merge']])
-                        st.session_state['export_base'] = st.session_state['export_base'].drop_duplicates()
-                        st.session_state['export_base'] = st.session_state['export_base'].reset_index(drop=True)
+                    add_all_col, add_select_col = st.columns(2)
+                    with add_all_col:
+                        if st.button("Add all to Custom Export"):
+                            st.session_state['export_base'] = pd.concat([st.session_state['export_base'], st.session_state['export_merge']])
+                            st.session_state['export_base'] = st.session_state['export_base'].drop_duplicates()
+                            st.session_state['export_base'] = st.session_state['export_base'].reset_index(drop=True)
+                    with add_select_col:
+                        select_custom_index = st.multiselect("Select rows to add to Custom Export", options=st.session_state['export_merge'].index, default=[])
+                        if st.button("Add selected to Custom Export"):
+                            st.session_state['export_base'] = pd.concat([st.session_state['export_base'], st.session_state['export_merge'].iloc[select_custom_index]])
+                            st.session_state['export_base'] = st.session_state['export_base'].drop_duplicates()
+                            st.session_state['export_base'] = st.session_state['export_base'].reset_index(drop=True)
                 with clear_export:
                     if st.button("Clear Custom Export"):
                         st.session_state['export_base'] = pd.DataFrame(columns=st.session_state['working_frame'].columns)