Sort file by their last modified date with QfileSystemModel

[redstoneleo]

I want to use QtableView and QfileSystemModel to show all the files in a folder , I want the file list is sorted by their last modified date ,now I have already reimplement QsortFilterProxyModel ,
my code is here
@
import sys
from PyQt4.QtGui import *
from PyQt4.QtCore import *

class SortProxyModel(QSortFilterProxyModel):
def lessThan(self, left_index, right_index):
left_var = left_index.data(Qt.DisplayRole)
right_var = right_index.data(Qt.DisplayRole)
return (left_var <= right_var)

if name == 'main':

app =QApplication(sys.argv)      
ui =QMainWindow()   

model= QFileSystemModel ()      
model.setRootPath(QDir.currentPath())   
             
proxy = SortProxyModel()
proxy.setSourceModel(model) 
proxy.sort(3)
    
table = QTableView()
table.setModel(model);   
table.setRootIndex(model.index(QDir.currentPath()));   

ui.setCentralWidget(table)
ui.resize(800, 600)
ui.show()      
app.exec_()

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but I don’t know what index should I give to setRootIndex() , can you help ?