How to Build a dictionary from a text file in Python

Question

I have a text file with entries that look like this :

JohnDoe

Assignment 9  
Reading: NO  
header: NO  
HW: NO  
Solutions: 0 
show: NO  
Journals: NO  
free: NO  
Finished: NO  
Quiz: 0  
Done     
Assignment 3  
E-book: NO  
HW: NO  
Readings: NO  
Show: 0  
Journal: NO 
Study: NO  
Test: NO  
Finished: NO  
Quiz: 0  
Done

This is a small sample. The file has several students in it. Each student has two assignments under their name and they only pass if the line that starts with "Finished" in each assignment reads "Finished: YES". All of the data under each assignment is disorganized, but somewhere under each assignment a line will say "Finished: YES (or NO)" I need a way to read the file and say whether or not any of the students have passed. So far, I have

def get_entries( file ):
with open( "dicrete.txt.rtf", 'rt') as file:
    for line in file:
        if "Finished" in line:
            finished, answer = line.split(':')
            yield finished, answer

# dict takes a sequence of  `(key, value)` pairs and turns in into a dict
print dict(get_entries( file ))

I can only get this code to return a single entry (the first "Finished" it reads as key and "YES or NO" as value, which is what I want, but I want it to return Every line in the file that that starts with "Finished". So the sample data I provided I want to return a dict with 2 entries {Finished:"NO" , Finished:"NO"}

You can only have 1 value per key, but that value can be another dictionary or tuple. Maybe shoot for {"Finished": ("NO", "NO")}. Possibly better {"Assignment 9": {"Finished": "NO", ... }, "Assignment 3": {"Finished": "NO", ...}} — cmd, Feb 07 '13 at 22:43
How are the student records delimited from each other? Is it `JohnDoe\n[blank line]\nAssignment \d\n` ? — the wolf, Feb 07 '13 at 22:59
Yes, except there in no blank line in the real file. I couldnt get it to work in my question without leaving a blank in between — Joe, Feb 07 '13 at 23:04
@cmd could you give me a clue on how to get something like {"Finished": ("NO", "NO")} ... im not sure where to insert code for that — Joe, Feb 07 '13 at 23:05
There is only one file. This is one entry in the file. The only task is to say if any of the students have passed. So I figure Ill make a dict like I described then write some simple Boolean expression to tell me whether or not anyone passed — Joe, Feb 07 '13 at 23:14
Suppose you have `'JohnDoe':{...,'Finished':'NO',...,'Finished':'YES',...}` and `'JackBlack':{...,'Finished':'YES',...,'Finished':'NO',...}` How will you separate John from Jack in this one file? What separates the students from each other in the one file? — the wolf, Feb 07 '13 at 23:34

score 2 · Accepted Answer · answered Feb 07 '13 at 22:32

2

Dictionaries can only store one mapping per key. So, you can never have a dictionary that has two different entries for the same key.

Consider using a list of two-tuples instead, like [("Finished", "NO"), ("Finished", "NO")].

answered Feb 07 '13 at 22:32

nneonneo

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Ah this makes sense. I have to run out for an hour but I'll try this out and report back. Thanks nneonneo – Joe Feb 07 '13 at 22:34

Adam Smith · Answer 2 · 2015-04-09T06:30:58.310

Sounds like you need a better data model! Let's look at that, shall we?

Let's define an Assignment class that we can call with all the lines of text between Assignment: # and Finished: YES/NO.

class Assignment(object):
    def __init__(self, id, *args, **kwargs):
        self.id = id
        for key,val in kwargs.items():
            setattr(self, key.lower(), val)
        finished = getattr(self, 'finished', None)
        if finished is None:
            raise AttributeError("All assignments must have a 'finished' value")
        else:
            self.finished = True if finished.lower() == "yes" else False

    @classmethod
    def from_string(cls, s):
        """Builds an Assignment object from a string

        a = Assignment.from_string('''Assignment: 1\nAttributes: Go Here\nFinished: yes''')
        >>> a.id
        1
        >>> a.finished
        True"""
        d = dict()
        id = None
        for line in s.splitlines():
            key,*val = map(str.strip, line.split(":"))
            val = ' '.join(val) or None
            if key.lower().startswith('assignment'):
                id = int(key.split()[-1])
                continue
            d[key.lower()] = val
        if id is not None:
            return cls(id, **d)
        else:
            raise ValueError("No 'Assignment' field in string {}".format(s))

Once you have your model, you'll need to parse your input. Luckily this is actually pretty simple.

def splitlineson(s, sentinel):
    """splits an iterable of strings into a newline separated string beginning with each sentinel.

    >>> s = ["Garbage", "lines", "SENT$", "first", "group", "SENT$", "second", "group"]
    >>> splitlineson(s, "SENT$")
    iter("SENT$\nfirst\ngroup",
         "SENT$\nsecond\ngroup")"""

    lines = []
    for line in s:
        if line.lower().strip().startswith(sentinel.lower()):
            if any((sentinel.lower() in line.lower() for line in lines)):
                yield "\n".join(lines)
            lines = [line.strip()]
        else:
            if line:
                lines.append(line.strip())
    yield "\n".join(lines)

with open('path/to/textfile.txt') as inf:
    assignments = splitlineson(inf, "assignment ")

assignment_list = [Assignment.from_string(a) for a in assignments]

How to Build a dictionary from a text file in Python

2 Answers2