1/4 Mile Calculator using PyQt5 in Python

Last Updated : 01 Aug, 2020

Prerequisite : Introduction to pyqt-5

In this article, we will see how we can create a quarter(1/4) mile calculator using PyQt5. Quarter mile calculator is used to determine the terminal speed (trap speed) and quarter-mile elapsed time (ET) of a vehicle based on its weight and power.

Below image shows how the 1/4 mile calculator looks like :

The quarter-mile calculator employs three distinct empirical equations to determine the quarter-mile elapsed time (ET). These are as follows:

1. Roger Huntington's Equation:

Time = 6.290 × (Weight / Power)^(1/3)

2. Geoffrey Fox's Equations:

Time = 6.269 × (Weight / Power)^(1/3)

3. Patrick Hale's Equations:

Time = 5.825 × (Weight / Power)^(1/3)

Note: Here weight is in Pound (lb) and power is in horsepower (hp) units.

GUI Implementation Steps :
1. Create a heading label that display the calculator name
2. Create label and combo box pair for selecting equation, label to show what user has to select and combo box to select
3. Similarly create a pair of label and line edit to get the weight and power of car
4. Create a push button to calculate the time
5. Create a label to show the calculated time

Back-End Implementation :
1. Make the combo box non editable
2. Make the line edit to accept only the number as input
3. Add action to the push button
4. Inside the push button action get the text of the line edits
5. Check if the line edit text is empty or zero then return so that function will not execute further
6. Convert the text value into integer
7. Get the selected option from the combo box and set constant value according to it
8. Calculate the time and show this value through the label

Below is the implementation :

Python3

# importing required libraries
from PyQt5.QtWidgets import *
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import *
from PyQt5.QtCore import *

import sys


class Window(QMainWindow):

    def __init__(self):
        super().__init__()

        # setting title
        self.setWindowTitle("Python ")

        # width of window
        self.w_width = 400

        # height of window
        self.w_height = 450

        # setting geometry
        self.setGeometry(100, 100, 
                         self.w_width, 
                         self.w_height)

        # calling method
        self.UiComponents()

        # showing all the widgets
        self.show()

    # method for components
    def UiComponents(self):

        # creating head label
        head = QLabel("1/4 Mile Calculator", 
                      self)

        # setting geometry to the head
        head.setGeometry(0, 10, 400, 60)

        # setting font
        font = QFont('Times', 15)
        font.setBold(True)
        font.setItalic(True)
        font.setUnderline(True)

        # setting font to the head
        head.setFont(font)

        # setting alignment of the head
        head.setAlignment(Qt.AlignCenter)

        # setting color effect to the head
        color = QGraphicsColorizeEffect(self)
        color.setColor(Qt.darkCyan)
        head.setGraphicsEffect(color)

        # creating a label
        e_label = QLabel("Equation", self)

        # setting properties  label
        e_label.setAlignment(Qt.AlignCenter)
        e_label.setGeometry(20, 100, 170, 40)
        e_label.setStyleSheet("QLabel"
                              "{"
                              "border : 2px solid black;"
                              "background : rgba(70, 70, 70, 35);"
                              "}")
        e_label.setFont(QFont('Times', 9))

        # creating a combo box to selected equation
        self.equation = QComboBox(self)

        # adding items to the combo box
        items = ["Huntington", "Fox", "Hale"]
        self.equation.addItems(items)

        # setting properties to the combo box
        self.equation.setFont(QFont('Times', 9))
        self.equation.setGeometry(200, 100, 180, 40)
        self.equation.setEditable(False)


        # creating a label
        w_label = QLabel("Car Weight (lb)", self)

        # setting properties to the label
        w_label.setAlignment(Qt.AlignCenter)
        w_label.setGeometry(20, 150, 170, 40)
        w_label.setStyleSheet("QLabel"
                              "{"
                              "border : 2px solid black;"
                              "background : rgba(70, 70, 70, 35);"
                              "}")
        w_label.setFont(QFont('Times', 9))

        # creating a QLineEdit object
        self.weight = QLineEdit(self)

        # accepting only number as input
        onlyInt = QIntValidator()
        self.weight.setValidator(onlyInt)

        # setting properties to the line edit
        self.weight.setGeometry(200, 150, 180, 40)
        self.weight.setAlignment(Qt.AlignCenter)
        self.weight.setFont(QFont('Times', 9))

        # creating a label
        p_label = QLabel("Engine Power (hp) ", self)

        # setting properties to the years label
        p_label.setAlignment(Qt.AlignCenter)
        p_label.setGeometry(20, 200, 170, 40)
        p_label.setStyleSheet("QLabel"
                              "{"
                              "border : 2px solid black;"
                              "background : rgba(70, 70, 70, 35);"
                              "}")
        p_label.setFont(QFont('Times', 9))

        # creating a QLineEdit object
        self.power = QLineEdit(self)

        # accepting only number as input
        onlyInt = QIntValidator()
        self.power.setValidator(onlyInt)

        # setting properties to the line edit
        self.power.setGeometry(200, 200, 180, 40)
        self.power.setAlignment(Qt.AlignCenter)
        self.power.setFont(QFont('Times', 9))


        # creating a push button
        calculate = QPushButton("Calculate Time", self)

        # setting geometry to the push button
        calculate.setGeometry(125, 270, 150, 40)

        # adding action to the calculate button
        calculate.clicked.connect(self.calculate_action)

        # creating a label to show percentile
        self.result = QLabel(self)

        # setting properties to result label
        self.result.setAlignment(Qt.AlignCenter)
        self.result.setGeometry(30, 340, 340, 80)
        self.result.setWordWrap(True)
        self.result.setStyleSheet("QLabel"
                                  "{"
                                  "border : 3px solid black;"
                                  "background : white;"
                                  "}")
        self.result.setFont(QFont('Arial', 11))

    # method for calculating the 
    # quarter-mile elapsed time (ET)
    def calculate_action(self):


        # getting weight of car
        weight = self.weight.text()

        # getting power of engine
        power = self.power.text()

        # if no input is given close the function
        if len(weight) == 0 or len(power) == 0:
            return

        # converting weight into integer
        weight = int(weight)

        # converting power into integer
        power = int(power)

        # if user enter total value as 0
        # return the function
        if power == 0 or weight == 0:
            return

        # getting the selected equation index
        equation = self.equation.currentIndex()

        # setting constant value according to the equation
        # Roger Huntington's constant
        if equation == 0:
            constant = 6.290

        # Geoffrey Fox's constant
        elif equation == 1:
            constant = 6.269

        # Patrick Hale's constant
        else:
            constant = 5.825

        # calculating the time
        result = constant * ((weight/power)**(1/3))

        # formatting the time
        result = "{:.2f}".format(result)

        # setting text to the result label
        self.result.setText("1/4 Mile Elapsed Time : "
                            + str(result) + " seconds")


# create pyqt5 app
App = QApplication(sys.argv)

# create the instance of our Window
window = Window()

# start the app
sys.exit(App.exec())