making a pie chart question

[Ri0o]

hi, i'm new in python programming
i'm trying to write a simple program that processes a text file containing grades for a class, extracts the desired grades, count the number of grades in each grade segment and genrate a pie chart for grades,(A1) .
http://pages.cpsc.ucal gary.ca/~zongpeng/CPSC231/assignments/A3/a3.pdf

txt file:http://pages.cpsc.ucal gary.ca/~zongpeng/CPSC231/assignments/A3/grades1.txt

i was able to extract the 6th column with this code

infile = open('grades1.txt','r')
all_lines = infile.readlines()
all_lines = all_lines[1:]
all_lines = all_lines[:-2]

i need help in assigning a grade to the results
and that's what i got so far but it doesn't seem to be working

A+ =[10]
A = [9,10)
A- =[8,9)
B+ =[7,8)
B =[6,7)
B- =[5,6)
C+ =[4,5)
C =[3,4)
D+ =[2,3)
F =[0,1)


grades=["ABCDA"]
i=0
total=0
while i<len(grades):
    if grades[i]  =='A':
        total=total+1
        i=i+1
print total

any help would be really appreciated

[bvdet]

You do not have the sixth column with your code. You have a list of all the lines in the file minus the first and last two lines. The sixth column would be saved with this code:

f = open("grades.txt")
sixthCol = [line.split()[5] for line in f.readlines()[1:-1]]
f.close()

You should store the data in a form that can be accessed for information. I would suggest a dictionary of dictionaries, but you can tabulate the information in a list of lists or tuples, whatever you are comfortable with. Here's some psuedocode:

Open file, create a file object
Read first line, save as column labels (strip and split the line)
Initialize a dictionary
Iterate on the file object (for line in fObj:)
....Assign dictionary key ID (line[0]) to a dictionary with column labels
........as keys and items (line[1:]) as values.
Close file object.

This can be accomplished with just a few lines of code. A column of grades can be summed like this:

>>> gradeA1 = sum([float(dd[key]['A1']) for key in dd])
>>> A1
1128.0
>>>

Here's a hint to create the dictionary for each line in the file:

>>> listA = ['A', 'B', 'C']
>>> listB = ['12', '13', '14']
>>> dict(zip(listA, listB))
{'A': '12', 'C': '14', 'B': '13'}
>>>

You need to find a way to convert a number grade into a letter grade. Here's where a dictionary would work well again. Assume a '9.5' is the same as a '9', and we can take the integer. Assign the intergers 0-10 to the corresponding letter grade. Then we can do this:

>>> grade = '7.5'
>>> gradeDict[int(float(grade))]
'B+'
>>>

Good luck. Post again if you have more questions.
HTH
BV