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Sub Set Search Visualizer using PyQt5
  • Difficulty Level : Medium
  • Last Updated : 06 May, 2020

In this article we will see how we can make a PyQt5 application which will visualize the subset search algorithm.

Sub Set Search : Sometimes we encounter the problem of checking if one list is just an extension of the list i.e just a superset of one list. This kind of problems are quite popular in competitive programming.

Examples –

Input: list = [1, 2, 3, 4, 5, 6, 7], sub-list = [2, 4, 7]

Output : List Found



Input: list = [1, 2, 3, 4, 5, 6, 7], sub-list = [5, 1, 7]
Output : List Found

GUI implementation steps :

1. Create a list of label according to the given list of numbers
2. Set their text, border, color and geometry with respective gap from each other
3. Each label height should be proportional to the value of each number
4. Create a start and pause push button to start the searching and pause the searching
5. Create a result label to show the searching status

Back end implementation steps :
1. Create label list corresponding to the given numbers
2. Create variable for the list index and sub-list index and flag for searching
3. Add action to the push button their action should change the flag status i.e start action should make flag true and pause action should make flag false and a counter to count number of matches
4. Create timer object which calls a method after every specific time
5. Inside the timer method check for the flag is flag is true begin the perfect sub-list search algorithm
6. Check for the first element of sub-list with first element of the list if found increment sub-list index, increment counter and reset the index of list else increment list index
7. If the index becomes equal to the list length stop the search and show result as not found.
8. If counter becomes equal to the length of the sub-list show result as found.

Below is the implementation




# importing libraries
from PyQt5.QtWidgets import *
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import *
from PyQt5.QtCore import *
  
import sys
  
  
class Window(QMainWindow):
    # list of numbers
    number = [1, 2, 3, 4, 5, 6, 7, 8, 9
                 10, 11, 12, 13, 14, 15]
  
    # desired list
    desired = [10, 11, 8, 4]
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("Sub Set Search")
  
        # setting geometry
        self.setGeometry(100, 100, 600, 400)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
    # method for widgets
    def UiComponents(self):
  
        # start flag
        self.start = False
  
        # list to hold labels
        self.label_list = []
  
        # match sub list
        self.match = []
  
        # index of both list
        self.list_index = 0
        self.sub_index = 0
  
        # local counter
        c = 0
  
        # iterating list of numbers
        for i in self.number:
            # creating label for each number
            label = QLabel(str(i), self)
  
            # adding background color and border
            label.setStyleSheet("border : 1px solid black;
                                 background : white;")
  
            # aligning the text
            label.setAlignment(Qt.AlignTop)
  
            # setting geometry using local counter
            # first parameter is distance from left 
            # and second is distance from top
            # third is width and forth is height
            label.setGeometry(50 + c * 30, 50, 20, i * 10 + 10)
  
            # adding label to the label list
            self.label_list.append(label)
  
            # incrementing local counter
            c = c + 1
  
        # creating push button to start the search
        self.search_button = QPushButton("Start Search", self)
  
        # setting geometry of the button
        self.search_button.setGeometry(100, 270, 100, 30)
  
        # adding action to the search button
        self.search_button.clicked.connect(self.search_action)
  
        # creating push button to pause the search
        pause_button = QPushButton("Pause", self)
  
        # setting geometry of the button
        pause_button.setGeometry(100, 320, 100, 30)
  
        # adding action to the search button
        pause_button.clicked.connect(self.pause_action)
  
        # creating label to show the result
        self.result = QLabel("To search : " + str(self.desired), self)
  
        # setting geometry
        self.result.setGeometry(320, 280, 250, 40)
  
        # setting style sheet
        self.result.setStyleSheet("border : 3px solid black;")
  
        # adding font
        self.result.setFont(QFont('Times', 10))
  
        # setting alignment
        self.result.setAlignment(Qt.AlignCenter)
  
        # creating a timer object
        timer = QTimer(self)
  
        # adding action to timer
        timer.timeout.connect(self.showTime)
  
        # update the timer every 300 millisecond
        timer.start(300)
  
    # method called by timer
    def showTime(self):
  
        # checking if flag is true
        if self.start:
  
            # if index exceeds limit
            if self.list_index >= len(self.number):
  
                # stop the search and show result not found
                self.start = False
                self.result.setText("Not Found")
                return
  
            # check for the element
            if self.desired[self.sub_index] == self.number[self.list_index]:
  
                # append it the match counter
                self.match.append(self.list_index)
  
                # make label color yellow and rest of whitee color
                for i in range(len(self.label_list)):
                    self.label_list[i].setStyleSheet(
                          "border : 1px solid yellow;"
                          "background-color : white;"
                                                     )
                      
                    # dor matched label make them yellow color
                    if i in self.match:
                        self.label_list[i].setStyleSheet(
                                 "border : 2px solid yellow;"
                                 "background-color : yellow;" )
  
                # increment sub index
                self.sub_index += 1
  
                # reset the list index
                self.list_index = 0
  
            # if not found
            else:
  
                # make checked index label grey
                self.label_list[self.sub_index + self.list_index].setStyleSheet(
                                     "border :" "1px solid black;"
                                     "background-color : grey;" )
  
                # increment list index
                self.list_index += 1
  
            # if matches become equal to desired list
            if len(self.match) == len(self.desired):
                # stop search
                self.start =False
  
                # show result
                self.result.setText("Found at : " + str(self.match))
  
                # make matched index green
                for i in self.match:
                    self.label_list[i].setStyleSheet(
                            "border : 2px solid green;"
                            "background-color : lightgreen;")
  
  
  
    # method called by search button
    def search_action(self):
  
        # making flag true
        self.start = True
  
        # showing text in result label
        self.result.setText("Started searching...")
  
    # method called by pause button
    def pause_action(self):
  
        # making flag false
        self.start = False
  
        # showing text in result label
        self.result.setText("Paused")
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

Output :

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