[Tutor] Reading Data From File

[Chris Castillo]

On 7/26/09, Dave Angel <davea at ieee.org> wrote:
> Chris Castillo wrote:
>> ya i was kind of in a hurry composing the email earlier. sorry for the
>> typos and misunderstanding. This is what I actually have.
>>
>> grades = []
>> names = []
>> gradeTotal = 0
>> numStudents = 0
>>
>> inputFile = open("input.txt", "r")
>>
>> for line in inputFile:
>>     if line.strip().isdigit():
>>         grade = float(line)
>>         if grade != 0.0:
>>             gradeTotal += grade
>>             grade = grades.append(grade)
>>         else:
>>             name = line.strip()
>>             name = names.append(name)
>>
>>
>> So even If I take the stuff out that you said, My structure still
>> wouldn't be right because I'm processing everything all at once with
>> no way to reference any of the grades with the student. How do I
>> structure this differently to do that? That's what I'm having trouble
>> with.
>>
>> On 7/25/09, Dave Angel <davea at dejaviewphoto.com> wrote:
>>
>>> ctcast at gmail.com wrote:
>>>
>>>> grades = []
>>>> names = []
>>>> gradeTotal = 0
>>>> numStudents = 0
>>>>
>>>> inputFile = open("input.txt", "r"
>>>>
>>>> for line in inputFile:
>>>> if line.strip().isdigit():
>>>> grade = float(line)
>>>> if grade != 0.0:
>>>> gradeTotal += grade
>>>> grade = grades.append(grade)
>>>> else:
>>>> name = line.strip()
>>>> name = names.append(name)
>>>>
>>>> This just loops over the entire file basically and just continually
>>>> adds the grades to the grades list and names to the names list. How do
>>>> I just process each student's set of grades before moving on to the
>>>> next one (since there is a zero terminating value telling the loop
>>>> that a new student and his or her grades are about to follow)
>>>>
>>>> By the way I'm not worrying about determining the letter grade average
>>>> right now, i'm importing a module I wrote after I figure this part out.
>>>>
>>>> On Jul 25, 2009 8:34am, bob gailer <bgailer at gmail.com> wrote:
>>>>
>>>>> I concur with wesley and dave re homework.
>>>>>
>>>> <snip>
>>>>
>>>>
>>> There are syntax errors of at least two kinds here.  The first is you're
>>> missing a trailing parenthesis.  And the second is you lost all your
>>> indentation when you retyped the code.  It'd really be better if you
>>> pasted the actual code instead.  Not much of a problem in this case, at
>>> least if I guess the same as you had, but in many cases the indentation
>>> *is* the problem.
>>>
>>> Next problem is that you're assuming that list.append() returns
>>> something useful. It doesn't return anything, which is to say it returns
>>> "None."  So it's not useful to do:
>>>      grade = grades.append(grade)
>>>
>>> just leave off the left half of that.  And likewise leave off the name=
>>> from the other call to append().
>>>
>>> The next problem is that you have two independent lists, but no way to
>>> correlate which elements of one correspond to which elements of the
>>> other. So you have a choice to make.  Do you need all the data for
>>> post-processing, or is it enough that you print it out, and discard it
>>> afterwards?
>>>
>>> I'll assume that you'd answer that it's enough to just be able to print
>>> it out.  In that case, you just need some well placed print statements.
>>> Each time you come to a line with a zero in it, you have enough
>>> information to print out one student's information.  And in this case,
>>> you don't need a list of students, just the name of the current one.
>>>
>>> Do you expect any numbers to be non-integers?  I'd assume so because you
>>> used the float() function instead of int().  But isdigit() is going to
>>> be a problem if there's a decimal in there.
>>>
>>> DaveA
>>>
>>>
>>>
> (In a mailing list like this one, putting a response at the top of your
> message is called top-posting, and makes it harder for the next person
> to see the sequence of messages.)
>
> As I said before:
>     *So you have a choice to make.  Do you need all the data for
> post-processing, or is it enough that you print it out, and discard it
> afterwards?*
>
> I tried to assume an answer, but it looks like you stopped reading
> before that point.  So I'll try again, with a little more detail.
>
> Each time you come to a line with a zero in it, you have enough
> information to print out one student's information.  You know the
> current student, you know all his scores.  So you could print it out at
> that point in the loop, rather than waiting till the entire program is past.
>
> If you're not sure what I'm talking about, first put in a test for the 0
> line.  Add in a single print that prints out name and grades at that
> point.  You do know that you can print a list, just the same as any
> other variable?
>
>
> Once you see you have enough data at that point, you'll have to make a
> minor change to eliminate this student's data from getting printed again
> for the next one.
>
> Then it's just a question of formatting the print nicely.  So you
> replace the single print with a function call, passing it the name and
> grades, and format the information in that function.
>
> And if you won't try what I said, then at least answer the question.
>
> DaveA
>
>
No I didn't stop reading your reply. I just figured since I said in my
original post of my problem that I needed to process the information
for one student before moving on to the next that you wouldn't
disregard that information.