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Creative Commons Attribution Non-Commercial Share Alike License. http://creativecommons.org/licenses/by-nc-sa/3.0/ Original Developer: Beth Simon, 2009 bsimon@cs.ucsd.edu. CSE8A Lecture 20. Read next class: read pg 293-300 Freshman seminar:

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  1. Creative Commons AttributionNon-Commercial Share Alike License • http://creativecommons.org/licenses/by-nc-sa/3.0/ • Original Developer: Beth Simon, 2009bsimon@cs.ucsd.edu

  2. CSE8A Lecture 20 • Read next class: read pg 293-300 • Freshman seminar: • Peer Instruction: Exploring a Revolution in College Science Teaching • Find out more about the theory behind clicker use • Analyze data from this and previous classes! • CSE 8A Art Show! Sat Nov 14 10:30-12 noon • Submit either your collage or chromakey (one per pair) • Art show open to all UCSD students • JSOE High School Outreach Day -- >110 high schoolers (and their parents) • We want MORE, GREAT people in CSE at UCSD!

  3. Midterm: Avg 83%90-80-70-60min 55% on individual final • Answers posted on line tomorrow • Midterms available for pickup Thurs/Fri in lab hours and in class

  4. By the end of today’s class you should be able to… • LG41: Read, trace, and write code to change the volume of a Sound object (using for each, while and for loops) • LG42: Compare and contrast the difference between changing the Color of Pixels in a Picture to changing the volume of SoundSamples in a Sound.

  5. How would we fill in this SampleSound[]

  6. The Sample Rate that the Sound class ASSUMES is 22KHz:How long is a SampleSound[] in a Sound object of 1 second? • 22 elements • 11,000 elements • 22,000 elements • 44,000 elements • We can’t tell from the data provided

  7. Write code which makes the following changes • Here’s a Sound String fileName = FileChooser.pickAFile(); Sound noise = new Sound(fileName); SoundSample[] noiseArray = noise.getSamples(); <<< PICK SOME CODE >>> int i = 0; while (i < noiseArray.length) { SoundSample sample = noiseArray[i]; int foo = sample.getValue(); sample.setValue(foo/2); } for (SoundSample sample: noiseArray) { int foo = sample.getValue(); sample.setValue(foo/2); } for (int i = noiseArray.length/2; i < noiseArray.length) { SoundSample sample = noiseArray[i]; int foo = sample.getValue(); sample.setValue(foo/2); }

  8. What does that code do? • But before we do that…

  9. So modified from the midterm: 0: Pixel[] pixelArray = this.getPixels(); 1: int mystery; 2: for(int i = pixelArray.length/4; i < 3*pixelArray.length/4; i++) 3: { 4: mystery = (pixelArray[i].getBlue() + pixelArray[i].getGreen() + pixelArray[i].getRed() ) / 3; 5: Color thing = new Color(mystery, mystery, mystery); 6: pixelArray[i].setColor(thing); 7: } 8: • This code modifies the middle half (from the top and bottom) of the picture • This code modifies the middle half (from the left and right) of the picture • This code loops over the pixels in the Pixel array starting at length/4 and up to 2*length/4 and gets the red, blue and green values adds them up and divides by 3 and sets that pixel to the calculated value

  10. Questions of the form:What does this code do should have what kind of answer? • A short sentence your grandmother can understand • A short sentence that describes the loop structure used • A short sentence that describes both the loop structure used and the method calls executed inside the loop • A paragraph at least 50 words long that the causes the graders’ eyes to glaze over

  11. REVIEW: Looking at this code… • Here’s a Sound String fileName = FileChooser.pickAFile(); Sound noise = new Sound(fileName); SoundSample[] noiseArray = noise.getSamples(); <<< PICK SOME CODE >>> int i = 0; while (i < noiseArray.length) { SoundSample sample = noiseArray[i]; int foo = sample.getValue(); sample.setValue(foo/2); } for (SoundSample sample: noiseArray) { int foo = sample.getValue(); sample.setValue(foo/2); } for (int i = noiseArray.length/2; i < noiseArray.length) { SoundSample sample = noiseArray[i]; int foo = sample.getValue(); sample.setValue(foo/2); }

  12. What does that code do • Makes a lower pitched sound during first half of play • Makes a quieter sound during first half of play • Makes a lower pitched sound during second half of play • Makes a quieter sound during second half of play • For each SoundSample element if the array it gets the Value and stores that in an int and then sets the Value with something that is half that

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