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Interpolation Search visualizer using PyQt5
  • Last Updated : 06 May, 2020

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

The Interpolation Search is an improvement over Binary Search for instances, where the values in a sorted array are uniformly distributed. Binary Search always goes to the middle element to check. On the other hand, interpolation search may go to different locations according to the value of the key being searched. For example, if the value of the key is closer to the last element, the interpolation search is likely to start search toward the end side.

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 a 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 lower higher and position 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 interpolation search algorithm
6. Check if value lies within the range if not show output as not found else continue
7. If the index of lower index is greater then higher index stop the search and show result as not found
8. Calculate the position index through the interpolation search formula
9. Check if the desired value is at position index if matches show result as found
10. If desired value is not equal then update the lower and higher index according to the desired value.

Below is the implementation

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# 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 = [10, 12, 13, 16, 18, 19, 20, 21
                  22, 23, 24, 33, 35, 42, 47]
  
    # desired value
    desired = 24
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("Interpolation 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 = []
  
        # position for keeping index
        self.position = 0
  
        # lower index
        self.lo = 0
  
        # higher index
        self.hi = len(self.number) - 1
  
        # 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 * 2 + 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:
  
            # Interpolation Search
            # checking if desired number is with in the range
            if (self.desired < self.number[self.lo] or 
                  self.desired > self.number[self.hi]):
  
                # make flag false
                self.start = False
                # show result as not found
                self.result.setText("Not Found")
  
            # if lower index become greater then higer index
            if self.lo > self.hi:
  
                # make flag false
                self.start = False
                # show result as not found
                self.result.setText("Not Found")
  
            else:
                # lower index is equal to higher index
                if self.lo == self.hi:
  
                    # checking if it matches desired value
                    if self.number[self.lo] == self.desired:
  
                        # show result
                        self.result.setText("Found at index : " + str(self.lo))
                        # make result label color green
                        self.label_list[self.lo].setStyleSheet(
                                     "border : 2px solid green;"
                                     "background-color : lightgreen;")
  
                    else:
                        # make result color grey
                        self.label_list[self.lo].setStyleSheet(
                                     "border : 1px solid black;"
                                     "background-color : grey;")
  
                # Probing the position with keeping
                # uniform distribution in mind.
                self.position = self.lo + int(((float(self.hi - self.lo) /
                        ( self.number[self.hi] - self.number[self.lo])) * 
                          (self.desired - self.number[self.lo])))
  
                # checking if the position matches with desired value position
                if self.number[self.position] == self.desired:
  
                    # make flag false
                    self.start = False
  
                    # show result and make label color green
                    self.result.setText("Found at position : " + str(self.position))
                    self.label_list[self.position].setStyleSheet(
                                        "border : 2px solid green;"
                                        "background-color : lightgreen;")
  
                else:
  
                    # make label color grey
                    self.label_list[self.position].setStyleSheet(
                                      "border : 1px solid black;"
                                      "background-color : grey;")
  
                # If desired is larger, desired is in upper part
                if self.number[self.position] < self.desired:
                    # updating lowe index
                    self.lo = self.position + 1
  
                # If desired is smaller, desired is in lower part
                else:
                    # updating higher index
                    self.hi = self.position - 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 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

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