CS 101 - Introduction to Computing, Spring 2007

Lab 13

Reminder

In the ACCC Labs that have JES, it can be found by:

1. Clicking on Start
2. Then click on All Programs
3. Then click on Class Applications
4. Then click on Engineering
5. Finally click on Jython Environment for Students

Nested For Loops

def cropImage():
  
  #Allow the user to pick up an image file
  file = pickAFile()
  pic = makePicture(file)

  # decide the size of new image
  newWidth = 100
  newHeight = 150
  new_pic = makeEmptyPicture(newWidth, newHeight)

  # now decide starting with which part of image
  # we should crop the image
  start_x = 50
  start_y = 100

  # so we will crop the image starting from pixel
  # at row 100 column 50 and size of the image would be
  # 100 columns and 150 rows.
  for x in range(1, newWidth+1):
    for y in range(1, newHeight+1):

      # get pixel from original image
      orig_pixel = getPixel(pic, x+start_x, y+start_y);
      new_pixel = getPixel(new_pic, x, y);

      # get the color from original pixel
      c = getColor(orig_pixel)
      setColor(new_pixel, c)

  # Now return the new image
  return(new_pic)

In the above code the first loop uses the variable x as its index variable. This loop is often called the "outer loop". The second loop uses the variable y as its index variable. This loop is ofter called the "inner loop". The inner loop will be completely executed during each iteration of the outer loop. So in the above code the value of x will be 1 while the value of y changes from 1 to 150. Then while the value of x is 2, the value of y again changes from 1 to 150. This continues until the value of x finally becomes 100.

Lab Assignment 13

For this assignment, you are to write a JES function that will take two parameters and print out the family of multiplication sentences based on those parameters.

The multiplication sentences are to be of the form:

    multiplier * multiplicant = product

and the multiplicant is to range from 0 to the second parameter.

For example, if the parameters given to the function are 2 and 3, the function should write out the following:

   0 X 0 = 0
   0 X 1 = 0
   0 X 2 = 0
   0 X 3 = 0

   1 X 0 = 0
   1 X 1 = 1
   1 X 2 = 2
   1 X 3 = 3

   2 X 0 = 0
   2 X 1 = 2
   2 X 2 = 4
   2 X 3 = 6

Note, don't worry if you fill up the JES command window with all of these statements. That is to be expected for just about any parameter value. However, the space between the sentence families is something that you are to create.

The primary approach to be used for this assignment is to use 2 for loops where one loop is nested inside the other. The above example of output assumes the outer loop interates on the multiplier (the first operand in the sentences) while the inner loop iterates on the muliplicant (the second operand in the sentences).

Create a file using JES that will:

1. Contain a comment indicating
   • your Name,
   • Net-ID,
   • Course Name,
   • Assignment Name and
   • a short description of the assignment

2. Contain a JES function called lab13 () that will
   • Take two integer values as its parameters.
   • Write out the multiplication sentence families as described above.

Submittal of the Lab Assignment

• You are submit your program electronically by placing it in the digital drop box in blackboard.
• Programs that are correct and submitted by noon on the Wednesday the lab assignment is discussed will receive an extra 10% on the score of the lab.
• When saving your program, use a meaningful name like lab13.py.
• When submitting your lab assignment, place all of the needed files it in a zippped folder (even if you are only submitting one file) with the name of yournetid_labNum and submit that zipped folder to the digital drop box. For instance, if your net id is abc32 then the folder name should be abc32_lab13.

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