Strings from files to tuples in list

Question

I have a text file that looks like this:

3 & 221/73 \\\  
4 & 963/73 \\\  
5 & 732/65 \\\  
6 & 1106/59 \\\  
7 & 647/29 \\\  
8 & 1747/49 \\\  
9 & 1923/49 \\\  
10 & 1601/41 \\\  
6 & 512 \\\

I want to load the pairs of numbers into a list or a dictionary.

This is the code I have so far:

L = []
data1 = data.replace (" \\\\", " ")
data2 = data1.replace(" & "," ")
i=0
a=''
b=''
while data2[i] != None:
    if(a==''):
        while( data2[i] != '' ):
            a=a+data2[i]
            i = i + 1
        while(data2[i] !=''):
            b=b+data2[i]
            i = i + 1
    L.append((int(a),int(b)))
    a=''
    b=''
    i=i+1

But this is the error I get:

"while( data2[i] != '' ):  string out of range"  

Answer 1

You almost had it, like @Vor mentioned, your conditional statements were the issue. Text files don't end with None in Python so you can't do data2[i] != '' and data2[i] != None: .

with open("data.txt") as f:
    L=[]
    for line in f:
        line=line.replace(" \\\\\\", "").strip() #Replace \\\ and strip newlines
        a,b=line.split(' & ')                    #Split the 2 numbers
        L.append((int(a),b))                     #Append as a tuple

This approach would output a list of tuples, which you asked for:

>>> L
[(3, '221/73'), (4, '963/73'), (5, '732/65'), (6, '1106/59'), (7, '647/29'), (8, '1747/49'), (9, '1923/49'), (10, '1601/41'), (6, '512')]

Note: In your 3rd last line, when you append to L , you use int() on the b variable. Since the string is in the form of '221/73' , its not a valid integer. You could split the string and int() each individual number, but then it would divide the numbers, which is probably not what you want.

Answer 2

Here is a solution that is a bit less C-like and looks more like python. Without being sure what exactly the output is supposed to look like, a first guess lead me to this solution:

result = []

with open("test.txt") as f:
    lines = f.readlines()
    for l in lines:
            l = l.replace('\\', '')
            elements = l.split("&")
            elements = [x.strip() for x in elements]
            result.append((int(elements[0]), elements[1]))

print result

This is the output:

[(3, '221/73'), (4, '963/73'), (5, '732/65'), (6, '1106/59'), (7, '647/29'), (8, '1747/49'), (9, '1923/49'), (10, '1601/41'), (6, '512')]

Note that this is missing error handling, so if the file does not conform to your format, this will probably throw an exception.

Answer 3

I think you want to replace data2[i] != '' and data2[i] != None: with something like this i < len(data2) .

Also your code will fail on that line L.append((int(a),int(b))) because 221/73 is not a valid literal.