Linear Search Visualizer using PyQt5

In this article we will see how we can make a PyQt5 application which will visualize the linear search algorithm. Linear search or sequential search is a method for finding an element within a list. It sequentially checks each element of the list until a match is found or the whole list has been searched.

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 the 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 a variable to count the 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 4. Create a 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 linear search algorithm 6. If label value if not equal make its color grey then check for next, if value got found make label color green and stop the search and show the output in the result label. 7. If the index counter becomes equal to the list length stop the search and show result as not found.

Below is the implementation 

Python3

# 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 = [2, 3, 6, 9, 8, 12, 16, 7, 10, 5, 4, 11, 2, 13]
    def __init__(self):
        super().__init__()

        # setting title
        self.setWindowTitle("Linear 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 = []

        # desired value
        self.desired = 11

        # counter for keeping index
        self.counter = 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 fourth 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(350, 280, 200, 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 200 millisecond
        timer.start(200)

    # method called by timer
    def showTime(self):

        # checking if flag is true
        if self.start:
            # linear search

            # checking if the element is equal to desired element
            if self.label_list[self.counter].text() == str(self.desired):

                # make its color green
                self.label_list[self.counter].setStyleSheet(
                                  "border : 1px solid black;
                                   background : lightgreen;")

                # show result in result label
                self.result.setText("Found at index : "
                                     + str(self.counter))

                # make the start flag false
                self.start = False

                # resetting the counter
                self.counter = 0

            # if element is not equal
            else:

                # make the label color grey
                self.label_list[self.counter].setStyleSheet(
                                  "border : 1px solid black;
                                   background : grey;")

            # increment the counter
            self.counter += 1

            # if counter value become equal to list length
            if self.counter == len(self.label_list):

                # make start flag false
                self.start = False

                # show result i.e not found
                self.result.setText("Not Found")

    # 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 :