In this article we will see how we can make a PyQt5 application which will visualize the Binary search algorithm. Binary Search: Search a sorted array by repeatedly dividing the search interval in half. Begin with an interval covering the whole array. If the value of the search key is less than the item in the middle of the interval, narrow the interval to the lower half. Otherwise narrow it to the upper half. Repeatedly check until the value is found or the interval is empty. 
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 Algorithm implementation steps : 1. Create label list corresponding to the given numbers 2. Create variable for the first last and mid 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 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 binary search algorithm 6. Calculate mid value and check if mid value is equal then stop the search and make label green. 7. Show result as found else change the value of first and last search according to the mid value. Make the label grey color and continue the search. 8. If the index of first become greater than index of last stop the search and show result as not found.
Below is the implementation –
Python3
# importing librariesfrom PyQt5.QtWidgets import *from PyQt5 import QtCore, QtGuifrom PyQt5.QtGui import *from PyQt5.QtCore import *import sysclass Window(QMainWindow): # list of numbers number = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15] def __init__(self): super().__init__() # setting title self.setWindowTitle("Binary 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 = 9 # binary search variable self.first = 0 self.last = len(self.number) - 1 self.mid = 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 300 millisecond timer.start(300) # method called by timer def showTime(self): # checking if flag is true if self.start: # implementing binary search # finding mid index self.mid = (self.first + self.last)//2 # if first index become greater than last index if self.first > self.last: # make start flag false self.start = False # show output as not found self.result.setText("Not Found") # if mid value is equal to the desired value if self.number[self.mid] == self.desired: # make flag false self.start = False # show output in result label self.result.setText("Found at index : " + str(self.mid)) # set color of label to green self.label_list[self.mid].setStyleSheet( "border : 2px solid green; " "background-color : lightgreen") # if not equal to mid value else: # make color grey self.label_list[self.mid].setStyleSheet( "border : 1px solid black; " "background-color : grey") # mid value is higher if self.number[self.mid] > self.desired: # change last index self.last = self.mid - 1 # if mid value is smaller if self.number[self.mid] < self.desired: # change first index self.first = self.mid + 1 # 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 appApp = QApplication(sys.argv)# create the instance of our Windowwindow = Window()# start the appsys.exit(App.exec()) |
Output :
