In order for us to find the peaks and the valleys of this graph, we first will have to determine if the consecutive points in the sequence are increasing or decreasing. Once we have this information, we can find out if the graph is turning. That is, suppose we have the following three consecutive y-values:
20 30 15
When we see y=20 followed by y=30, we know that the y-coordinate has increased. With that information, when we see y=15, we can tell that the graph is turning. That is, the second point is a valley. You will learn more about that later.
For now, after having seen y=20 followed by y=30, we want to print a statement to indicate that the graph is increasing. When we see y=15, we want to print a statement to specify that the graph is decreasing.
We will base the "increasing" or "decreasing" on the original Cartesian coordinates, not the ones we used to draw the graph.
"""
Program: CS 115 Lab 5c
Author: Your name
Description: This program draws a graph and determines whether
consecutive points are increasing or decreasing.
"""
from graphics import *
def main():
window_height = 600
window = GraphWin('Graph', 800, window_height)
# Open the input file and read the number of points
pointsfile = open("points-test.txt", "r")
num_points = int(pointsfile.readline())
x = 20
first_y = int(pointsfile.readline()) # get the first y-coordinate
first_point = Point(x, window_height - first_y)
for i in range(1, num_points): # we already have the first point, so, start with 1.
# Read the next point and update x
second_y = int(pointsfile.readline())
x += 10
second_point = Point(x, window_height - second_y)
###### Print first_y and second_y
###### Complete this if-statement
if second_y is larger than first_y:
the graph is increasing
else:
the graph is decreasing
##### Copy this code from Part B
draw the line between first_point and second_point
draw a circle centered at first_point
# second_point becomes the first point of the next line
first_y = second_y
first_point = second_point
###### Copy this code from Part B
draw a circle centered at first_point
window.getMouse()
window.close()
main()
y of first point = 420, y of second point = 280 decreasing y of first point = 280, y of second point = 230 decreasing y of first point = 230, y of second point = 330 increasing y of first point = 330, y of second point = 230 decreasing y of first point = 230, y of second point = 140 decreasing y of first point = 140, y of second point = 190 increasing y of first point = 190, y of second point = 580 increasing y of first point = 580, y of second point = 210 decreasing y of first point = 210, y of second point = 580 increasing y of first point = 580, y of second point = 500 decreasing y of first point = 500, y of second point = 350 decreasing y of first point = 350, y of second point = 460 increasing y of first point = 460, y of second point = 550 increasing y of first point = 550, y of second point = 420 decreasing y of first point = 420, y of second point = 510 increasing y of first point = 510, y of second point = 360 decreasing y of first point = 360, y of second point = 330 decreasing