Simple graphics in python assignment

[isinc]

I have an assignment that I'm working on and am having trouble. Not too familiar with graphics. Any help/guidance would be much appreciated to see if what I have so far is okay and what I should do for the loop part. I will post assignment details and what i have so far.

You are given a dictionary named Stats, which is part of the template provided for this assignment. The template can be found at
http://dbis.ucdavis.edu/courses/ECS10-WQ08/Python/hw6-template.py
The dictionary manages information about the number of students of a particular major enrolled in a class. The dictionary looks as follows:
Stats = { "ECSE":8, "LCSI":6, "ECOM":13, "ABIT":4, "ACSM":3, "AEXH":2, \
"AEXP":9, "BULS":6, "APME":8, "BBMB":3, "EBCL":2, \
"EEEL":9, "LDES":4, "LMAT":3, "LPHY":3, "LPSC":4, "LUHU":4, \
"LUPS":5, "LUSS":2 }
Each pair consists of a string (major code) and a number, which tells you how many students of that major are enrolled in the class. For example, there are 8 students with the major ECSE and 4 students with the major LPSC.
Write a Python program that displays the information contained in the dictionary in the form of a chart analog to the one produced by the program graph01.py presented in class on 3/4/08. Your program should construct a chart like a bar graph, with major name above each bar on the graph.

Approach: Download the following two files in your ECS 10 folder: graphics22.py and hw6-template.py. Both files can be obtained from the assignment Web page. The template provides you with some kind of structure for the program. Take a look at the template! Next, you have to determine an appropriate size and coordinates for your window. For this, you can use the information about how many entries the dictionary has. Once this is in place, you have to
retrieve pairs from the dictionary, pair-by-pair. Note that you can’t do this directly on the dictionary, but you have to convert it to a list of pairs. Then, for each pair, you get the major code and count, print the major code (as string) and the count is used to determine the height of the line.

# Put your name and student ID here
# Don't forget to rename this file!
#
 
from graphics22 import *
 
#The dictionary has 19 entries.
Stats = { "ECSE":8, "LCSI":6, "ECOM":13, "ABIT":4, "ACSM":3, "AEXH":2, \
          "AEXP":9, "BULS":6, "APME":8, "BBMB":3, "EBCL":2, \
      "EEEL":9, "LDES":4, "LMAT":3, "LPHY":3, "LPSC":4, "LUHU":4, \
      "LUPS":5, "LUSS":2 }
 
 
# You have to define the window, its size, and an 
# appropriate coordinate system. The number of entries in the 
# dictionary and the maximum count of students gives you an 
# idea of the min and max x/y coordinates
def main(n):
    win = GraphWin("This is a 600 x 400 graph window",600,400)
    win.setBackground('white')
 
    # Let's define lower left and upper right for the coord.system
    x_min = -1.0      # make sure (0,0) is on the screen
    y_min = -1.0      # make sure (0,0) is on the screen
    x_max = n + 1.0   # give a little extra horizontal space
    y_max = n * 1.1   # give 10% extra vertical space
    win.setCoords(x_min, y_min, x_max, y_max)
 
    L = range(n)
    shuffle(L)
 
 
# Now, convert the dictionary to a list of pairs. That's easy...
swapDictionary = {}
 
for key, val in Stats.items():
    swapDictionary[val] = key
 
 
 
# Next, you have a loop that goes through that list, picks a pair
# (major and count) and constructs a vertical line of this pair
# at the correct position in the window. Note that the string (name
# of the major) goes on top of the vertical line. All this is very
# similar to the graph01.py program presented in class.
 
 
 
# wait for final mouse click!
win.getMouse()
win.close()
print "Done"
 

[jlm699]

A few things:
you must import random and then use random.shuffle(L) instead of just shuffle.
Except... what is the purpose of doing that? It's not used anywhere else in the code...

also, the bottom of your code should be more like this :

    # wait for a  mouse click and the close the window
if __name__ == '__main__':
    # You can call main() here
    # You need an instance of "win" to refer to here for things like:
    win.getMouse()
    # rest of your code...
 

To get this to run I had to get a reference to "win" by having that main function return an instance of the win and assigning a variable to the main() call...

For the loop I'd suggest something simple like:

for elem in Stats:
    print elem, Stats[elem]
 

I hope this helps, please don't hesitate to ask further.

[isinc]

Thanks for the quick response! Still a little confused how to actually get the program to draw the lines for each major and code. Something like:

    # Next, you have a loop that goes through that list, picks a pair
    # (major and count) and constructs a vertical line of this pair
    # at the correct position in the window. Note that the string (name
    # of the major) goes on top of the vertical line. All this is very
    # similar to the graph01.py program presented in class.
    for elem in Stats:
        print elem, Stats[elem]
        t = Key(Point(x,y+1), str(y))
        t.draw(win)
        line = Line(Point(x,0), Point(x,y))
        line.setFill("blue")
        line.draw(win) 

[jlm699]

Hmm... you're gettin' there. I don't know where that Key() came from though?

I did it using a Rectangle() with a Text() instance at the top... although I don't know if that's how your professor wants you to do it or not.

r = Rect(Point(i, 0), Point(i+1, '''number of students'''))
r.setFill(['red','blue','green'][i%3])
r.draw(win)
t = Text(Point(i + 0.5, '''number of students''' + 1))
t.setSize(8)
t.draw(win)
 

Where i is the index of the for loop interation (HINT: look into the Python function enumerate() )

[isinc]

Here is what I got. I feel i am pretty close. I just cant get the data from the dictionary to print on the graph. Instead, I get a graph with bars starting at 0 going to 19 with the numbers above each bar. I need the bars to vary according to the number of people in each major with the major code above each bar.

from random import shuffle
from graphics22 import *
 
Stats = { "ECSE":8, "LCSI":6, "ECOM":13, "ABIT":4, "ACSM":3, "AEXH":2, \
          "AEXP":9, "BULS":6, "APME":8, "BBMB":3, "EBCL":2, \
      "EEEL":9, "LDES":4, "LMAT":3, "LPHY":3, "LPSC":4, "LUHU":4, \
      "LUPS":5, "LUSS":2 }
 
def main(n):
    win = GraphWin("This is a 600 x 400 graph window",600,400)
    win.setBackground('white')
 
    # Let's define lower left and upper right for the coord.system
    x_min = -1.0      # make sure (0,0) is on the screen
    y_min = -1.0      # make sure (0,0) is on the screen
    x_max = n + 1.0   # give a little extra horizontal space
    y_max = n * 1.1   # give 10% extra vertical space
 
    L = range(n)
 
 
    # after setCoords all coordinates will be transformed!
    win.setCoords(x_min, y_min, x_max, y_max)
 
    swapDictionary = {}
    for key, val in Stats.items():
        swapDictionary[val] = key
 
    stats_dic = {"ECSE":8, "LCSI":6, "ECOM":13, "ABIT":4, "ACSM":3,
                    "AEXH":2, "AEXP":9, "BULS":6, "APME":8, "BBMB":3,
                    "EBCL":2, "EEEL":9, "LDES":4, "LMAT":3, "LPHY":3,
                    "LPSC":4, "LUHU":4, "LUPS":5, "LUSS":2 }
    for key, val in stats_dic.items():
        print key, val
 
    for i in range(n):
        x = i 
        y = L[i]
        t = Text(Point(x,y+1), str(y))
        t.draw(win)
        line = Line(Point(x,0), Point(x,y))
        line.setFill("blue")
        line.draw(win)
 
 
 
    # wait for final mouse click!
    win.getMouse()
    win.close()
    print "Done"
 
main(20)
 

[jlm699]

I get a graph with bars starting at 0 going to 19 with the numbers above each bar.

    L = range(n)
 
    for i in range(n):
        x = i 
        y = L[i]
        t = Text(Point(x,y+1), str(y))
        t.draw(win)
        line = Line(Point(x,0), Point(x,y))
        line.setFill("blue")
        line.draw(win)
 

You are very close, however you're doing something very wrong here. range(n) where n = 20 yields this: [0, 1, 2, 3, 4, 5, 6, ... 19].
Then in your for loop you're using these numbers instead of the contents of your Stats dictionary. I suggest getting rid of all references to range(n), and in your for loop just try the following:

for idx, elem in enumerate(stats_dict):
        print idx, elem, stats_dict[elem]
 

After you see the output of that loop you should understand what to fix in the for loop that you currently have.

[isinc]

All done, except I need the major codes above each bar on the graph, not the number of students in each major. Guidance?

from random import shuffle
from graphics22 import *
 
Stats = { "ECSE":8, "LCSI":6, "ECOM":13, "ABIT":4, "ACSM":3, "AEXH":2, \
          "AEXP":9, "BULS":6, "APME":8, "BBMB":3, "EBCL":2, \
      "EEEL":9, "LDES":4, "LMAT":3, "LPHY":3, "LPSC":4, "LUHU":4, \
      "LUPS":5, "LUSS":2 }
 
def main(n):
    win = GraphWin("This is a 600 x 400 graph window",600,400)
    win.setBackground('white')
 
    # Let's define lower left and upper right for the coord.system
    x_min = -1.0      # make sure (0,0) is on the screen
    y_min = -1.0      # make sure (0,0) is on the screen
    x_max = n + 1.0   # give a little extra horizontal space
    y_max = n * 1.1   # give 10% extra vertical space
 
 
 
    # after setCoords all coordinates will be transformed!
    win.setCoords(x_min, y_min, x_max, y_max)
 
    swapDictionary = {}
    for key, val in Stats.items():
        swapDictionary[val] = key
 
    stats_dic = {"ECSE":8, "LCSI":6, "ECOM":13, "ABIT":4, "ACSM":3,
                    "AEXH":2, "AEXP":9, "BULS":6, "APME":8, "BBMB":3,
                    "EBCL":2, "EEEL":9, "LDES":4, "LMAT":3, "LPHY":3,
                    "LPSC":4, "LUHU":4, "LUPS":5, "LUSS":2 }
 
    L = stats_dic
    for idx, elem in enumerate(stats_dic):
        x = idx
        y = L[elem]
        t = Text(Point(x,y+1), str(y))
        t.draw(win)
        line = Line(Point(x,0), Point(x,y))
        line.setFill("blue")
        line.draw(win)       
 
 
 
    # wait for final mouse click!
    win.getMouse()
    win.close()
    print "Done"
 
main(19)

[jlm699]

    stats_dic = {"ECSE":8, "LCSI":6, "ECOM":13, "ABIT":4, "ACSM":3,
                    "AEXH":2, "AEXP":9, "BULS":6, "APME":8, "BBMB":3,
                    "EBCL":2, "EEEL":9, "LDES":4, "LMAT":3, "LPHY":3,
                    "LPSC":4, "LUHU":4, "LUPS":5, "LUSS":2 }
 
    L = stats_dic
    for idx, elem in enumerate(stats_dic):
        x = idx
        y = L[elem]
        t = Text(Point(x,y+1), str(y))
        t.draw(win)
 

This is simple. Look at what you are assigning to the variable y, and then think about how you reference an element in a dictionary. You have y being the associated value of the dictionary element, which is what is being printed (the class size); however you want the key instead of the element (the class abbreviation). So simply swap str(y) (the value) for the key (what is used to access the value from the dictionary).