python - Selecting many rows in Qt table -

i trying create qtableview in qt efficient large tables. i've managed make display of data efficient defining own abstract table model:

from pyqt4 import qtcore, qtgui pyqt4.qtcore import qt   class datatablemodel(qtcore.qabstracttablemodel):      def columncount(self, index=none):         return 3      def rowcount(self, index=none):         return 10000      def headerdata(self, section, orientation, role):         if role != qt.displayrole:             return none         if orientation == qt.horizontal:             return 'c'         elif orientation == qt.vertical:             return 'r'      def data(self, index, role):         if not index.isvalid():             return none         if role == qt.displayrole:             return "({0},{1})".format(index.row(), index.column())  app = qtgui.qapplication([""]) viewer = qtgui.qtableview() model = datatablemodel() viewer.setmodel(model) viewer.show() 

this works fine, because data method called cells appear in field of view of table.

i want display existing selection of fraction of rows:

import numpy np selected_rows = np.where(np.random.random(10000) > 0.5)[0] 

i can tell table widget selection doing e.g.:

smodel = viewer.selectionmodel() row in selected_rows:     model_index = model.createindex(row, 0)     smodel.select(model_index, qtgui.qitemselectionmodel.select | qtgui.qitemselectionmodel.rows) 

however, inefficient. typically takes second select 1000-2000 rows, when in practice have tables millions of rows. there may ways of speeding loop, away loop altogether, , instead have qt ask me (similarly data itself) information selections within visible cells. possible, , if so, best way achieve this?

you should use second overloaded version of select, 1 accepts qitemselection instead of single index.

the qitemselection able select ranges of rows providing 2 argument constructor:

qitemselection(start_index, stop_index) 

moreover can merge items become single selection:

selection.merge(other_selection, flags) 

this suggest to:

1. sort indices of rows want select
2. use itertools.groupby group consecutive rows
3. use createindex qmodelindex of start-end indices of these groups
4. create qitemselection objects each group of rows
5. merge qitemselections single qitemselection
6. perform selection on model.

note want sort rows by index, not values.