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Lab 8

Lab 8. Exercise 1:. Follow the text’s suggestion and Google “color names list” Collect from the list a set of 25 colors or so and in a new Python program put them in a list data structure.

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Lab 8

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  1. Lab 8 Intro to Robots

  2. Exercise 1: • Follow the text’s suggestion and Google “color names list” • Collect from the list a set of 25 colors or so and in a new Python program put them in a list data structure. • Write code that creates a graphics window and then loops through the elements of the colors list, changing the color of the graphics window background. colors = [‘DarkCyan’, ‘DarkGoldenRod’, …] Intro to Robots

  3. Exercise 2: • Follow up on Exercise 1 by doing the following • Add a point on the graphics window each time you change the background color. • Use some kind of systematic method of assigning the point coordinates like (i,i) and increment i each time you change the background color. • The outcome will be something like: Intro to Robots

  4. Exercise 3: • In class we saw the code that draws the following picture. • Extend this code to draw the following picture. • Hint 1: Figure out what the four corner point coordinates will be. • Hint 2: Use 4 loops Intro to Robots

  5. Exercise 4: • Add to the program in Exercise 3 by including the codeto the loops that control the drawings of the lines. • What behaviour do you get? wait(0.3)L.undraw() Intro to Robots

  6. Exercise 5: • Consider the Bouncing Circle program # Moving circle; Animate a circle... from myro import * from random import * def main(): # create and draw the graphics window winWidth = winHeight = 500 w = GraphWin("Bouncing Circle", winWidth, winHeight) w.setBackground("white") # Create a red circle radius = 25 c = Circle(Point(53, 250), radius) c.setFill("red") c.draw(w) # Animate it dx = dy = 3 main() while timeRemaining(15): # move the circle c.move(dx, dy) # make sure it is within bounds center = c.getCenter() cx, cy = center.getX(), center.getY() if (cx+radius >= winWidth) or (cx-radius <= 0): dx = -dx if (cy+radius >= winHeight) or (cy-radius <= 0): dy = -dy wait(0.01) Intro to Robots

  7. Part 1: • Modify the previous program so that each time the Circle is moved it leaves a Point at its previous center. Intro to Robots

  8. Exercise 5, Part 2: • After you draw the Circle, draw a rectangle in the middle of the Bouncing Circle window and color it yellow: • Use the coordinates(200,100) and (300,400) • Now rerun the program and notice that the ballmoves behind the rectangle. R = (Rectangle(Point1,Point2)) # Point1 is the top left-hand corner # Point2 is the bottom right-hand corner (200,100) (300,400) Intro to Robots

  9. Exercise 5 (cont): • Modify the program so that the ball will bounce off the rectangle just like it bounces off the edge of the graphics window. • Initially there are four situations to consider: Intro to Robots

  10. Case 1: • If the ball approaches the rectangle side whose coordinates are given below then the test for the program variables is: (200,100) (300,100) cx + radius >= 200 and cx – radius <= 300 andcy between 100 and 400 program code: ( (cx + radius >= 200) and (cx – radius <= 300) and ( cy >= 100) and (cy <= 400)) (200,400) (300,400) Intro to Robots

  11. Cases 2, 3 and 4: • Evaluate the same expressions for the following three cases: • Put this code into the original program and watch the circle move around the window. Intro to Robots

  12. (200,100) (200,400) Exercise 5 (cont): • If you implement this code you will see that everything works well except at the corners. • In this case we can see that the test conditions fails. What part of it fails? ( (cx + radius >= 200) and (cx – radius <= 300) and ( cy >= 100) and (cy <= 400)) fails: Intro to Robots

  13. Exercise 5 (cont): In order for the circle to bounceoff the yellow rectangle it must be inside the outer rectangle in one of the areas labeled A, B, C, D or 1 … 8. This is not enough however. In theareas labeled 4 and 5 the circle caninside the outer rectangle but still not be touching the inner rectangle. Inside B, C, D condition: ? Inside 1 condition: inside outer rectangle and not in A, B, C or D and cx <= 200 and cy <= 100 and 200 – cx <= 100 – cy Inside 2 .. 8 condition? Inside 1 and touching rectanglecondition: inside 1 and (200 – cx)2 + (cy – 100)2 < radius2 Variables: (cx,cy) - center of circle radius – radius of circle Inside outer rectangle condition: cx + radius >= 200 and cx – radius <= 300 and cy + radius >= 100 and cy – radius <= 400Inside A condition: inside rectangle and cx >= 200 and cx <= 300 and cy <= 100 Intro to Robots

  14. Exercise 5 (cont): • Modify your program to take these new conditions into account. The pseudocode is: if inside outer rectangle: if inside A: flip dy elif inside B: flip dx elif inside C: flip dy elif inside D: flip dx elif inside 1: if touching inner rectangle: flip dy elif inside 2: if touching inner rectangle: flip dx . . . ( 6 more cases) Added clear rectangle tosee where Circle center iswhen Circle touches rectangle Intro to Robots

  15. Exercise 5 (cont): entered area 2 are exited correctly • A bug: Circle starts here back and forth, back andforth until it exits area 2 passed through area 8 ok entered area 8 and got “stuck” Intro to Robots

  16. Exercise 5, Bug Analysis: • Each time we move the Circle we move it 3 pixels on the x-axis and 3 pixels on the y-axis. • When we cross the line into the outer rectangle we flip either the x- or y- increment and the next move typically takes us back outside the rectangle. • However this is not necessarily true in the corners . . . . . . . . . bouncing back weare still inside and so flip again; this keepsus inside until the end of the line. Intro to Robots

  17. Exercise 5, Bug Solution: • When you enter the outer rectangle and flip either the x-increment or the y-increment you must not flip again until you have at least left the outer rectangle. • Our problem here is that once too far inside the outer rectangle we stay there by flipping back and forth. • Code Solution: Add a boolean flag to your program that gets turned on whenever you flip and only turned off once you leave the rectangle.Then don’t ever allow a flip to happen if the flag is turned on. Intro to Robots

  18. Exercise 5, Bug Solution Pseudocode • Exercise: Implement this pseudocode # outside while-loop turn flag off if inside outer rectangle: if flag turned on: continue # skips to top of while-loop if inside A: flip dy turn flag on elif inside B, C, D: . . . elif inside 1: if touching inner rectangle: # inside circular arc flip dy turn flag on elif inside 2, … , 8: . . . ( 6 more cases) else: # outside outer rectangle turn flag off Intro to Robots

  19. Exercise 5 (one last time) • Make the robot beep each time you flip the x- or y-increment. • Make it beep differently if it is hitting the outside will than if it is hitting the rectangle. Intro to Robots

  20. Exercise 6 (Sound): • The human ear can not distinguish between sounds which are very close together. • Execute the beep() command over a range of frequency values to determine your audible range. • Execute the beep() command over a range of close-by frequency pairs to see how far apart the pairs need to be for you to distinguish the sounds beep(1,300), beep(1,400), beep(1,1000), beep(1,2000), … beep(1, 300), beep(1, 305), … beep(1, 1000), beep(1, 1010), beep(1, 440), beep(1, 441) … Intro to Robots

  21. Exercise 7 (siren): • A siren is two sounds repeated constantly. • Find a good pair for sounds for a siren. Intro to Robots

  22. Exercise 8: Musical Scale Data Structure • In the past we have used the dictionary data structure to hold data that comes in pairs. • Remember the englishToSpanish dictionary in Chap 1? • Create a dictionary called notes with notes from 9 different octaves (from A0 to C8). These are the notes Scribbler is able to make. • Method 1: Key in by hand. • Method 2:: freqs = [‘C’, ‘C#’, D, ‘D#’, ‘E’, ‘F’, ‘F#’, ‘G’, ‘G#’, ‘A’, ‘A#’, ‘B’] notes = {} notes[‘A0’] = 27.5; notes[‘A#0’] = 29.14; notes[‘B0’] = 30.87; notes[‘C8’] = 4186.0 for i in range(7): j = 1 for f in freqs: notes[f+str(i+1)] = (notes[‘B0’])*2**(i+j/12.0) j = j+1 Intro to Robots

  23. Musical Notes: • Google ‘musical note frequencies’ and compare what you find there with the numbers you have created with the code on the previous page. Intro to Robots

  24. Exercise 9: • Pick a simple song you remember and make your robot play your song. • Remember that the robot can only play chords with two notes. Intro to Robots

  25. Exercise 10: • Working with another team in the lab, play a duet – one robot plays the treble clef and the other the bass clef notes. http://en.wikipedia.org/wiki/Clef Intro to Robots

  26. Exercise 11: • Since our robot may at times need to express emotion you might find some short tunes that express • Determination • Sadness • Victory • Curiosity • Plodding along • Full steam ahead • Any other emotions that seem appropriate … Intro to Robots

  27. Exercise 12: • Write a function that will draw a maple leaf.Now cover a graphics window with maple leaves of different sizes (small, medium, large) and colors (red, yellow, orange). def mapleLeaf(anchor point, size, color, window): . . . Intro to Robots

  28. Exercise 13: • Draw the following robot using the function: • Now use this function to draw the following picture. def drawRobot(anchor point, window): . . . def drawPyramid(window): . . . Intro to Robots

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