Answer
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Work Step by Step
# 12.18 (Tkinter: the BarChart class) Develop a class named BarChart that extends
# Canvas for displaying a bar chart:
# BarChart(parent, data, width = 400, height = 300)
# Where data is a list, each element in the list is a nested list that consists of a
# value, a title for the value, and a color for the bar in the bar chart. For example,
# for data = [[40, "CS", "red"], [30, "IS", "blue"], [50, "IT",
# "yellow"]], the bar chart is as shown in the left part of Figure 12.28. For data
# = [[140, "Freshman", "red"], [130, "Sophomore", "blue"],
# [150, "Junior", "yellow"], [80, "Senior", "green"]], the bar
# chart is as shown in the right part of Figure 12.28. Write a test program that displays
# two bar charts, as shown in Figure 12.28.
from tkinter import * # Import tkinter
width = 300
height = 200
class BarChart(Canvas):
def __init__(self, parent, data, width=400, height=300):
super().__init__(parent, width=width, height=height)
self.setData(data)
def setData(self, data):
self.__data = data
self.drawBarChart()
def drawBarChart(self):
bottomGap = 15
self.create_line(10, height - bottomGap, width - 10, height - bottomGap)
barWidth = (width - 20) / len(self.__data)
values = []
for x, y, z in self.__data:
values.append(x)
maxCount = int(max(values))
for i in range(len(self.__data)):
self.create_rectangle(i * barWidth + 10, height - (height - 10) * self.__data[i][0] / maxCount,
(i + 1) * barWidth + 10, height - bottomGap, fill=self.__data[i][2])
self.create_text(i * barWidth + 10 + barWidth / 2, height - bottomGap / 2,
text=self.__data[i][1])
class MainGUI:
def __init__(self):
window = Tk() # Create a window
window.title("BarChart Reusable Class") # Set title
canvas1 = BarChart(window, [[40, "CS", "red"], [30, "IS", "blue"], [50, "IT", "yellow"]], width=width,
height=height)
canvas1.grid(row=1, column=1)
canvas2 = BarChart(window,
[[140, "Freshman", "red"], [130, "Sophomore", "blue"], [150, "Junior", "yellow"],
[80, "Senior", "green"]],
width=width, height=height)
canvas2.grid(row=1, column=2)
window.mainloop() # Create an event loop
MainGUI()
