PyQt5 – 二进制搜索可视化工具

在这篇文章中，我们将看到如何制作一个PyQt5应用程序，将二进制搜索算法可视化。

二进制搜索： 通过重复地将搜索区间分成两半来搜索一个排序的数组。从一个覆盖整个数组的区间开始。如果搜索键的值小于区间中间的项，则将区间缩小到下半部分。否则将其缩小到上半部分。反复检查，直到找到该值或区间为空。

GUI的实施步骤：

1. 根据给定的数字列表创建一个标签列表

2. 设置它们的文字、边框、颜色和几何形状，彼此之间有一定的差距。

3. 每个标签的高度应与每个数字的值成比例
4. 创建一个开始和暂停的按钮来开始搜索和暂停搜索
5. 创建一个结果标签以显示搜索状态

**算法实施步骤： **

1. 创建对应于给定数字的标签列表

2. 为第一个、最后一个和中间的索引创建变量，并为搜索建立标志。

3. 为按钮添加动作，它们的动作应改变标志状态，即开始动作应使标志为真，暂停动作应使标志为假

4. 创建定时器对象，在每个特定时间后调用一个方法

5. 在定时器方法中检查标志，如果标志为真，则开始二进制搜索算法
6. 计算中间值，如果中间值相等，则停止搜索并使标签变成绿色。
7. 显示找到的结果，否则根据中间值改变第一次和最后一次搜索的值。使标签变成灰色并继续搜索。
8. 如果第一个索引大于最后一个索引，则停止搜索并将结果显示为未找到。

以下是执行情况

# 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]
 
    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 app
App = QApplication(sys.argv)
 
# create the instance of our Window
window = Window()
 
# start the app
sys.exit(App.exec())