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I created a very simple python program using GDAL to calculate the summary and reduction between two raster value like this :

    import os
    from osgeo import ogr, gdal
    from gdalconst import *
    import numpy as np

    # input First Raster using GDAL
    filename1 = raw_input("Input Raster 1 : ")
    raster1 = gdal.Open( filename1, GA_ReadOnly )
    Raster1_Value = np.array(raster1.GetRasterBand(1).ReadAsArray(), dtype ="float")

    # input Second Raster using GDAL
    filename2 = raw_input("Input Raster 2 : ")
    raster2 = gdal.Open( filename2, GA_ReadOnly )
    Raster2_Value = np.array(raster2.GetRasterBand(1).ReadAsArray(), dtype ="float")

    # Raster Parameter
    geotransform_ = raster1.GetGeoTransform()
    Col = raster1.RasterXSize
    print Col
    Row = raster1.RasterYSize
    Origin_X = geotransform_[0]
    Origin_Y = geotransform_[3]
    Cell_Size = geotransform_[1]

    # Choose Operator
    Operation = { "+" : "plus" , "-" : "minus" }
    Op = raw_input("Input Operator :")
    Condition  = Operation[Op]

    # Calculate
    if Condition == "plus" :
        Result = Raster1_Value + Raster2_Value
    elif Condition == "minus" :
        Result = Raster1_Value - Raster2_Value 
    print Result

    # Output Result in .asc
    filename_ras = raw_input("Output Raster PATH :")+'.asc'
    out = open(filename_ras, 'wb+')
    out.write('ncols         %i\n' % Col)
    out.write('nrows         %i\n' % Row)
    out.write('xllcorner     %f\n' % Origin_X)
    out.write('yllcorner     %f\n' % (Origin_Y - (Cell_Size * Row)) )
    out.write('cellsize      %i\n' % Cell_Size)
    out.write('NODATA_value  %i\n' % 0)
    np.savetxt(out, Result, fmt="%4i") 

The input will be refer to GDAL Raster data format and the output is ESRI ASCII data format. I've been make a QGIS plugin by using plugin builder and an user interface by using QT Designer, This is my UI i've been made so far :

enter image description here

so the UI python script will be like this :

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_praticeDialogBase(object):
    def setupUi(self, praticeDialogBase):
        praticeDialogBase.setObjectName(_fromUtf8("praticeDialogBase"))
        praticeDialogBase.resize(384, 300)
        self.button_box = QtGui.QDialogButtonBox(praticeDialogBase)
        self.button_box.setGeometry(QtCore.QRect(30, 240, 341, 32))
        self.button_box.setOrientation(QtCore.Qt.Horizontal)
        self.button_box.setStandardButtons(QtGui.QDialogButtonBox.Cancel|QtGui.QDialogButtonBox.Ok)
        self.button_box.setObjectName(_fromUtf8("button_box"))
        self.browse_raster1 = QtGui.QPushButton(praticeDialogBase)
        self.browse_raster1.setGeometry(QtCore.QRect(310, 40, 41, 23))
        self.browse_raster1.setObjectName(_fromUtf8("browse_raster1"))
        self.PATH_RASTER1 = QtGui.QLineEdit(praticeDialogBase)
        self.PATH_RASTER1.setGeometry(QtCore.QRect(110, 40, 191, 20))
        self.PATH_RASTER1.setObjectName(_fromUtf8("PATH_RASTER1"))
        self.PATH_RASTER2 = QtGui.QLineEdit(praticeDialogBase)
        self.PATH_RASTER2.setGeometry(QtCore.QRect(110, 70, 191, 20))
        self.PATH_RASTER2.setObjectName(_fromUtf8("PATH_RASTER2"))
        self.browse_raster2 = QtGui.QPushButton(praticeDialogBase)
        self.browse_raster2.setGeometry(QtCore.QRect(310, 70, 41, 23))
        self.browse_raster2.setObjectName(_fromUtf8("browse_raster2"))
        self.comboBox = QtGui.QComboBox(praticeDialogBase)
        self.comboBox.setGeometry(QtCore.QRect(110, 100, 131, 22))
        self.comboBox.setObjectName(_fromUtf8("comboBox"))
        self.comboBox.addItem(_fromUtf8(""))
        self.comboBox.addItem(_fromUtf8(""))
        self.PATH_RESULT = QtGui.QLineEdit(praticeDialogBase)
        self.PATH_RESULT.setGeometry(QtCore.QRect(110, 140, 191, 20))
        self.PATH_RESULT.setObjectName(_fromUtf8("PATH_RESULT"))
        self.browse_result = QtGui.QPushButton(praticeDialogBase)
        self.browse_result.setGeometry(QtCore.QRect(310, 140, 41, 23))
        self.browse_result.setObjectName(_fromUtf8("browse_result"))
        self.label = QtGui.QLabel(praticeDialogBase)
        self.label.setGeometry(QtCore.QRect(30, 40, 46, 13))
        self.label.setObjectName(_fromUtf8("label"))
        self.label_2 = QtGui.QLabel(praticeDialogBase)
        self.label_2.setGeometry(QtCore.QRect(30, 70, 46, 13))
        self.label_2.setObjectName(_fromUtf8("label_2"))
        self.label_3 = QtGui.QLabel(praticeDialogBase)
        self.label_3.setGeometry(QtCore.QRect(30, 100, 61, 20))
        self.label_3.setObjectName(_fromUtf8("label_3"))
        self.label_4 = QtGui.QLabel(praticeDialogBase)
        self.label_4.setGeometry(QtCore.QRect(30, 140, 46, 13))
        self.label_4.setObjectName(_fromUtf8("label_4"))

        self.retranslateUi(praticeDialogBase)
        QtCore.QObject.connect(self.button_box, QtCore.SIGNAL(_fromUtf8("accepted()")), praticeDialogBase.accept)
        QtCore.QObject.connect(self.button_box, QtCore.SIGNAL(_fromUtf8("rejected()")), praticeDialogBase.reject)
        QtCore.QMetaObject.connectSlotsByName(praticeDialogBase)

    def retranslateUi(self, praticeDialogBase):
        praticeDialogBase.setWindowTitle(_translate("praticeDialogBase", "pratice", None))
        self.browse_raster1.setText(_translate("praticeDialogBase", "...", None))
        self.browse_raster2.setText(_translate("praticeDialogBase", "...", None))
        self.comboBox.setItemText(0, _translate("praticeDialogBase", "Plus", None))
        self.comboBox.setItemText(1, _translate("praticeDialogBase", "Minus", None))
        self.browse_result.setText(_translate("praticeDialogBase", "...", None))
        self.label.setText(_translate("praticeDialogBase", "Raster 1", None))
        self.label_2.setText(_translate("praticeDialogBase", "Raster 2", None))
        self.label_3.setText(_translate("praticeDialogBase", "Operation", None))
        self.label_4.setText(_translate("praticeDialogBase", "Result", None))

And this is my default script from plugin builder :

from PyQt4.QtCore import QSettings, QTranslator, qVersion, QCoreApplication
from PyQt4.QtGui import QAction, QIcon
# Initialize Qt resources from file resources.py
import resources_rc
# Import the code for the dialog
from pratice_dialog import praticeDialog
import os.path


class pratice:
    """QGIS Plugin Implementation."""

    def __init__(self, iface):
        """Constructor.

        :param iface: An interface instance that will be passed to this class
            which provides the hook by which you can manipulate the QGIS
            application at run time.
        :type iface: QgsInterface
        """
        # Save reference to the QGIS interface
        self.iface = iface
        # initialize plugin directory
        self.plugin_dir = os.path.dirname(__file__)
        # initialize locale
        locale = QSettings().value('locale/userLocale')[0:2]
        locale_path = os.path.join(
            self.plugin_dir,
            'i18n',
            'pratice_{}.qm'.format(locale))

        if os.path.exists(locale_path):
            self.translator = QTranslator()
            self.translator.load(locale_path)

            if qVersion() > '4.3.3':
                QCoreApplication.installTranslator(self.translator)

        # Create the dialog (after translation) and keep reference
        self.dlg = praticeDialog()

        # Declare instance attributes
        self.actions = []
        self.menu = self.tr(u'&pratice')
        # TODO: We are going to let the user set this up in a future iteration
        self.toolbar = self.iface.addToolBar(u'pratice')
        self.toolbar.setObjectName(u'pratice')

    # noinspection PyMethodMayBeStatic
    def tr(self, message):
        """Get the translation for a string using Qt translation API.

        We implement this ourselves since we do not inherit QObject.

        :param message: String for translation.
        :type message: str, QString

        :returns: Translated version of message.
        :rtype: QString
        """
        # noinspection PyTypeChecker,PyArgumentList,PyCallByClass
        return QCoreApplication.translate('pratice', message)


    def add_action(
        self,
        icon_path,
        text,
        callback,
        enabled_flag=True,
        add_to_menu=True,
        add_to_toolbar=True,
        status_tip=None,
        whats_this=None,
        parent=None):
        """Add a toolbar icon to the toolbar.

        :param icon_path: Path to the icon for this action. Can be a resource
            path (e.g. ':/plugins/foo/bar.png') or a normal file system path.
        :type icon_path: str

        :param text: Text that should be shown in menu items for this action.
        :type text: str

        :param callback: Function to be called when the action is triggered.
        :type callback: function

        :param enabled_flag: A flag indicating if the action should be enabled
            by default. Defaults to True.
        :type enabled_flag: bool

        :param add_to_menu: Flag indicating whether the action should also
            be added to the menu. Defaults to True.
        :type add_to_menu: bool

        :param add_to_toolbar: Flag indicating whether the action should also
            be added to the toolbar. Defaults to True.
        :type add_to_toolbar: bool

        :param status_tip: Optional text to show in a popup when mouse pointer
            hovers over the action.
        :type status_tip: str

        :param parent: Parent widget for the new action. Defaults None.
        :type parent: QWidget

        :param whats_this: Optional text to show in the status bar when the
            mouse pointer hovers over the action.

        :returns: The action that was created. Note that the action is also
            added to self.actions list.
        :rtype: QAction
        """

        icon = QIcon(icon_path)
        action = QAction(icon, text, parent)
        action.triggered.connect(callback)
        action.setEnabled(enabled_flag)

        if status_tip is not None:
            action.setStatusTip(status_tip)

        if whats_this is not None:
            action.setWhatsThis(whats_this)

        if add_to_toolbar:
            self.toolbar.addAction(action)

        if add_to_menu:
            self.iface.addPluginToMenu(
                self.menu,
                action)

        self.actions.append(action)

        return action

    def initGui(self):
        """Create the menu entries and toolbar icons inside the QGIS GUI."""

        icon_path = ':/plugins/pratice/icon.png'
        self.add_action(
            icon_path,
            text=self.tr(u'pratice'),
            callback=self.run,
            parent=self.iface.mainWindow())


    def unload(self):
        """Removes the plugin menu item and icon from QGIS GUI."""
        for action in self.actions:
            self.iface.removePluginMenu(
                self.tr(u'&pratice'),
                action)
            self.iface.removeToolBarIcon(action)
        # remove the toolbar
        del self.toolbar


    def run(self):
        """Run method that performs all the real work"""
        # show the dialog
        self.dlg.show()
        # Run the dialog event loop
        result = self.dlg.exec_()
        # See if OK was pressed
        if result:
            # Do something useful here - delete the line containing pass and
            # substitute with your code.
            pass

My Question is, what should i write to integrate that User Interface script with my main program?

for example filename1 will be base on PATH_RASTER1 and browse_raster1 button to find the path location of my raster file. All that i've learned from many online literatures is that the main program must be write on run() function.

I know that my program is to simple and useless to be build as plugin but my purpose is to understand how PyQT works on QGIS plugin environment.

  • 1
    Just edit with QtCreator your UI file generated by Plugin Builder. It will change praticeDialog() class wich was used to create your dialog window self.dlg = praticeDialog(). – dmh126 Aug 15 '15 at 9:56

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