Adjust the size (width/height) of a custom QTableWidget

Question

I need a QTableWidget based on a QTabelModel and QTableView with some buttons added above the table. See the following figure:

The width of the QTableWidget should be adjusted so that it is not smaller than a reasonable minimum and not extend beyond the buttons above it; in particular, the size of the columns 1, 2, and 4 should be adjusted to their contents, and the 3rd column, Aberrations, should be expanded to fill in the gap on the right side. I'd like to know how to do this in code.

The following is a minimal example of the code I use for the custom QTableWidget (PyQt5, Python3):

from PyQt5 import QtGui, QtCore, QtWidgets
import numpy as np

#-- Table Model
class MyTableModel(QtCore.QAbstractTableModel):

    def __init__(self, data, parent=None, *args):
        super(MyTableModel, self).__init__(parent)

        # table data
        self.table_data = data
        self.rows_nr, self.columns_nr = data.shape

        # vertical & horizontal header labels
        self.hheaders = ["Head-{}".format(i) for i in range(self.columns_nr)]
        self.vheaders = ["Row-{}".format(i) for i in range(self.rows_nr)]

    # nr of rows
    def rowCount(self, parent):
        return self.rows_nr

    # nr of columns
    def columnCount(self, parent):
        return self.columns_nr

    # row and column headers
    def headerData(self, section, orientation, role):
        if role == QtCore.Qt.DisplayRole:
            if orientation == QtCore.Qt.Horizontal:
                return self.hheaders[section]
            #END if

        #ELSE:
        return QtCore.QVariant()

    # display table contents
    def data(self, index, role=QtCore.Qt.DisplayRole):        
        r_ = index.row()
        c_ = index.column()

        if role == QtCore.Qt.DisplayRole:
            return "{}".format(data[r_, c_])
        #ELSE:
        return QtCore.QVariant()

    # set data
    def setData(self, index, value, role):

        r_ = index.row()
        c_ = index.column()

        # editable fields
        if role == QtCore.Qt.EditRole:
            # interprete values
            self.table_data[r_,c_] = str(value)

        return True

    # view/edit flags
    def flags(self, index):
        r_ = index.row()
        c_ = index.column()

        return QtCore.Qt.ItemIsEnabled


class MyTableWidget(QtWidgets.QWidget):
    def __init__(self, data, *args):
        super(MyTableWidget, self).__init__(*args)

        #-- table model
        tablemodel = MyTableModel(data=data, parent=self)

        #-- table view
        tableview = QtWidgets.QTableView()
        tableview.setModel(tablemodel)
        tableview.verticalHeader().hide() # hide vertical/row headers

        # size policy
        tableview.setSizeAdjustPolicy(QtWidgets.QAbstractScrollArea.AdjustToContents)
        tableview.setSizePolicy(QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Minimum)

        #-- layouts
        #--- buttons
        button_hlayout = QtWidgets.QHBoxLayout()
        button_hlayout.addWidget(QtWidgets.QPushButton("Button 1"))
        button_hlayout.addWidget(QtWidgets.QPushButton("Button 2"))
        button_hlayout.addWidget(QtWidgets.QPushButton("Button 3"))

        #--- table
        table_layout = QtWidgets.QVBoxLayout()
        table_layout.addLayout(button_hlayout)
        table_layout.addWidget(tableview)
        self.setLayout(table_layout)
#----------------------------------------

#-- produce sample data
data = np.empty(shape=(3,4), dtype=np.object)
for r in range(3):
    for c in range(4):
        data[r,c] = str(list(range((r+1) * (c+1))))

app = QtWidgets.QApplication([""])
w = MyTableWidget(data=data)
w.show()
app.exec_()

Befall

Answer 1

void QHeaderView::setSectionResizeMode(int logicalIndex, QHeaderView::ResizeMode mode)

Sets the constraints on how the section specified by logicalIndex in the header can be resized to those described by the given mode. The logical index should exist at the time this function is called.

from PyQt5 import QtGui, QtCore, QtWidgets
import numpy as np

#-- Table Model
class MyTableModel(QtCore.QAbstractTableModel):

    def __init__(self, data, parent=None, *args):
        super(MyTableModel, self).__init__(parent)

        # table data
        self.table_data = data
        self.rows_nr, self.columns_nr = data.shape

        # vertical & horizontal header labels
        self.hheaders = ["Head-{}".format(i) for i in range(self.columns_nr)]
        self.vheaders = ["Row-{}".format(i) for i in range(self.rows_nr)]

    # nr of rows
    def rowCount(self, parent):
        return self.rows_nr

    # nr of columns
    def columnCount(self, parent):
        return self.columns_nr

    # row and column headers
    def headerData(self, section, orientation, role):
        if role == QtCore.Qt.DisplayRole:
            if orientation == QtCore.Qt.Horizontal:
                return self.hheaders[section]
            #END if

        #ELSE:
        return QtCore.QVariant()

    # display table contents
    def data(self, index, role=QtCore.Qt.DisplayRole):        
        r_ = index.row()
        c_ = index.column()

        if role == QtCore.Qt.DisplayRole:
            return "{}".format(data[r_, c_])
        #ELSE:
        return QtCore.QVariant()

    # set data
    def setData(self, index, value, role):

        r_ = index.row()
        c_ = index.column()

        # editable fields
        if role == QtCore.Qt.EditRole:
            # interprete values
            self.table_data[r_,c_] = str(value)

        return True

    # view/edit flags
    def flags(self, index):
        r_ = index.row()
        c_ = index.column()

        return QtCore.Qt.ItemIsEnabled


class MyTableWidget(QtWidgets.QWidget):
    def __init__(self, data, *args):
        super(MyTableWidget, self).__init__(*args)

        #-- table model
        tablemodel = MyTableModel(data=data, parent=self)

        #-- table view
        tableview = QtWidgets.QTableView()
        tableview.setModel(tablemodel)
        tableview.verticalHeader().hide() # hide vertical/row headers
        
        #-- +++
        tableview.setAlternatingRowColors(True)
        tableview.horizontalHeader().setSectionResizeMode(QtWidgets.QHeaderView.Stretch)
        tableview.horizontalHeader().setSectionResizeMode(0, QtWidgets.QHeaderView.ResizeToContents)
        tableview.horizontalHeader().setSectionResizeMode(1, QtWidgets.QHeaderView.ResizeToContents)
        tableview.horizontalHeader().setSectionResizeMode(3, QtWidgets.QHeaderView.ResizeToContents)

        # size policy
        tableview.setSizeAdjustPolicy(QtWidgets.QAbstractScrollArea.AdjustToContents)
        #tableview.setSizePolicy(QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Minimum) # ---
        tableview.setSizePolicy(QtWidgets.QSizePolicy.Expanding, QtWidgets.QSizePolicy.Minimum)# +++

        #-- layouts
        #--- buttons
        button_hlayout = QtWidgets.QHBoxLayout()
        button_hlayout.addWidget(QtWidgets.QPushButton("Button 1"))
        button_hlayout.addWidget(QtWidgets.QPushButton("Button 2"))
        button_hlayout.addWidget(QtWidgets.QPushButton("Button 3"))

        #--- table
        table_layout = QtWidgets.QVBoxLayout()
        table_layout.addLayout(button_hlayout)
        table_layout.addWidget(tableview)
        self.setLayout(table_layout)
#----------------------------------------

#-- produce sample data
data = np.empty(shape=(3,4), dtype=np.object)
for r in range(3):
    for c in range(4):
        data[r,c] = str(list(range((r+1) * (c+1))))

app = QtWidgets.QApplication([""])
w = MyTableWidget(data=data)
w.show()
app.exec_()

In the code above, tableview.horizontalHeader().SetSectionResizeMode(QtWidgets.QHeaderView.Stretch) applies the Stretch mode to all columns, and the remaining 3 operators set the corresponding columns to the ResizeToContents mode.

The resizing behaviour of the widget window is determined by setSizePolicy method. In this case, the policy can be also tableview.setSizePolicy(QtWidgets.QSizePolicy.Expanding, QtWidgets.QSizePolicy.Minimum), which allows the user to enlarge or shrink the widget window.

Thomism

Thanks for the answer. So, here, horizontalHeader().setSectionResizeMode(QtWidgets.QHeaderView.Stretch) applies the Stretch mode to all columns, and the other 3 statements set the respective columns to ResizeToContents mode; right? – Befall

Another issue which I see is that the stretched column (nr. 2) can be enlarged by the user (by enlarging the window), but it cannot be shortened back to the original size! Is this the expected behaviour? Is it possible to allow the user resizing to work in both ways? – Befall

Sorry for the vagueness. Just try to enlarge the widget window by dragging the bottom-right corner. The section which is in Stretch mode will then expand. Yet, trying to drag the very corner back in order to return to the original size, is not possible; that is, the column width can expand but not shrink. How can this behaviour be modified, if possible? – Befall

I appended the additional information in the comments to the answer. – Befall