----------------------------------- wtd Thu Sep 29, 2005 2:54 pm Test Your Skills: Python Thread ----------------------------------- Challenge #1: Join Lists and other iterable objects are very important in Python. It's often also important for us to be able to output a nicely formatted representation of these important objects. The join function represents one important means of doing this. >>> ', '.join(['1', '2', '3']) '1, 2, 3' Reimplement it Now, the challenge is to reimplement this function. The Reward 50 bits, and my admiration. Admiration only if the bits system is borked. The rules The function must accept two arguments: 'lst', the list to join; and 'sep', the separator to place between the items. Separators may be more than one character. The function may not use the keywords 'return' or 'if', or any semi-colons. Semi-colons are permitted as the separator string passed to the function as an argument. The function may not modify any arguments passed to it. The function may not exceed one line of code. Bonus 50 additional bits or simply added admiration if you can improve upon the standard library's "join" and make it work with lists containing elements that are not strings. ----------------------------------- wtd Sat Nov 26, 2005 6:20 pm ----------------------------------- Given the snippet of code from the interactive interpreter: >>> foo() bar >>> Write the code which makes this possible. Your code may not include any kind of input/output operation. ----------------------------------- wtd Mon Nov 28, 2005 11:22 am ----------------------------------- Given the snippet of code from the interactive interpreter: >>> foo() bar >>> Write the code which makes this possible. Your code may not include any kind of input/output operation. The solution, since no one has expressed interest, is: class foo(object): def __repr__(self): return "bar" ----------------------------------- [Gandalf] Mon Nov 28, 2005 4:40 pm ----------------------------------- I have not looked into Python too much, so forgive any mistakes, but... def foo(): return "bar" Could you not just do that? ----------------------------------- wtd Mon Nov 28, 2005 5:48 pm ----------------------------------- "]I have not looked into Python too much, so forgive any mistakes, but... def foo(): return "bar" Could you not just do that? In that case, what'd you'd see would be: >>> foo() "bar" >>> ----------------------------------- Hikaru79 Tue Nov 29, 2005 8:15 pm ----------------------------------- Okay, my turn to give one :) This is my first try at this, so be gentle. I'll come up with more soon :) Here it is. Add one line of code so that the following line executes properly (and gives the result that one would intuitively assume). Dict(foo=5, bar=12, foobar=9) I hope this isn't too easy, hard, pointless, etc :oops: ----------------------------------- wtd Tue Nov 29, 2005 8:43 pm ----------------------------------- for line in file("foo.txt"): print line Add one line of code to this such that it prints "Whoops! Empty file." if there's nothing in the file. ----------------------------------- bugzpodder Thu Sep 07, 2006 12:20 pm ----------------------------------- if os.path.getsize("foo.txt") = 0 : print "empty file" ----------------------------------- wtd Thu Sep 07, 2006 12:46 pm ----------------------------------- Not what I was looking for. :) What I am looking for is part of the loop. ----------------------------------- bugzpodder Fri Sep 08, 2006 3:29 pm ----------------------------------- hint ----------------------------------- wtd Fri Sep 08, 2006 10:43 pm ----------------------------------- See the Tutorial under the Documentation section on python.org. It has the answer. ----------------------------------- Roman Sat Aug 09, 2008 1:09 am Re: Test Your Skills: Python Thread ----------------------------------- Challenge #1: Join >>> ', '.join(['1', '2', '3']) '1, 2, 3' I'm very new at this, but couldn't you just do def joinFctn(sep, lst): print sep.join(lst) P.S. Only three years late x_x ----------------------------------- [Gandalf] Thu Oct 02, 2008 8:00 am Re: Test Your Skills: Python Thread ----------------------------------- Roman, you couldn't do that because you're just using the join function and printing the result. The point is the re-implement it completely. Here's my try: def join(lst, sep): return reduce(lambda x, y: x + sep + y, lst) What I don't understand is, if we're not supposed to return anything or modifying any arguments, then what is the function supposed to do? Of course, there's probably some 'trick' that I'm missing completely. ;) !!! ----------------------------------- Zeroth Thu Oct 02, 2008 9:05 am Re: Test Your Skills: Python Thread ----------------------------------- Your mixing up the challenges Gandalf. One of the challenges, you cannot return anything. The other you can. ----------------------------------- SS_198 Sun Feb 22, 2009 2:32 pm Re: Test Your Skills: Python Thread ----------------------------------- Here a way to make your python program write something without typing return : or print python : 3.0 def helloWorld(): print ("helloWorld") # this line does not print helloworld helloWorld() # This line print hello world # you can type helloWorld() as many times as you like, and will print > HelloWorld < ----------------------------------- zuzelvp Sat May 22, 2010 10:39 am Re: Test Your Skills: Python Thread ----------------------------------- re-implement it completely. Here's my try: def join(lst, sep): return reduce(lambda x, y: x + sep + y, lst) What I don't understand is, if we're not supposed to return anything or modifying any arguments, then what is the function supposed to do? Of course, there's probably some 'trick' that I'm missing completely. ;) !!![/quote] join = lambda lst, sep: reduce(lambda x, y: x + sep + y, lst, '').replace(sep, '', 1) ----------------------------------- zuzelvp Sat May 22, 2010 10:49 am ----------------------------------- Okay, my turn to give one :) This is my first try at this, so be gentle. I'll come up with more soon :) Here it is. Add one line of code so that the following line executes properly (and gives the result that one would intuitively assume). Dict(foo=5, bar=12, foobar=9) I hope this isn't too easy, hard, pointless, etc :oops: Anyone coming from languages like C# will need to learn this one :wink: ----------------------------------- DtY Sat May 22, 2010 2:15 pm ----------------------------------- Okay, my turn to give one :) This is my first try at this, so be gentle. I'll come up with more soon :) Here it is. Add one line of code so that the following line executes properly (and gives the result that one would intuitively assume). Dict(foo=5, bar=12, foobar=9) I hope this isn't too easy, hard, pointless, etc :oops:What do you mean "properly", I assume returns the dictionary that contains those? Dict = dict # Or def Dict(**params): return params Here's another, if anyone's interested; In one line, write a function that will transpose a two dimensional list, that is, if the input were to look like this as a grid: [code]A B C D E F G H I[/code] The output looks like this: [code]A D G B E H C F I[/code]. Some languages have a function that will do this, python doesn't, without using some syntax that may appear odd. I'm pretty sure I learned how to do this from here, so at least one person should know right away. ----------------------------------- cavetroll Sat May 22, 2010 10:37 pm ----------------------------------- Okay, my turn to give one :) This is my first try at this, so be gentle. I'll come up with more soon :) Here it is. Add one line of code so that the following line executes properly (and gives the result that one would intuitively assume). Dict(foo=5, bar=12, foobar=9) I hope this isn't too easy, hard, pointless, etc :oops:What do you mean "properly", I assume returns the dictionary that contains those? Dict = dict # Or def Dict(**params): return params Here's another, if anyone's interested; In one line, write a function that will transpose a two dimensional list, that is, if the input were to look like this as a grid: I think for the transposing of a list, you can just do zip(*lst) Where lst is your initial two dimensional list. Although it will actually return a tuple of tuples, I assume that's what you were looking for? ----------------------------------- tedying Fri Jan 20, 2012 11:43 pm ----------------------------------- Okay, my turn to give one :) This is my first try at this, so be gentle. I'll come up with more soon :) Here it is. Add one line of code so that the following line executes properly (and gives the result that one would intuitively assume). Dict(foo=5, bar=12, foobar=9) I hope this isn't too easy, hard, pointless, etc :oops: def Dict(**x): ??return x ----------------------------------- tedying Fri Jan 20, 2012 11:45 pm ----------------------------------- Okay, my turn to give one :) This is my first try at this, so be gentle. I'll come up with more soon :) Here it is. Add one line of code so that the following line executes properly (and gives the result that one would intuitively assume). Dict(foo=5, bar=12, foobar=9) I hope this isn't too easy, hard, pointless, etc :oops:What do you mean "properly", I assume returns the dictionary that contains those? Dict = dict # Or def Dict(**params): return params Here's another, if anyone's interested; In one line, write a function that will transpose a two dimensional list, that is, if the input were to look like this as a grid: My python definitely has this function: >>> a=((1,2,3),(4,5,6),(7,8,9)) >>> zip(*a) ----------------------------------- tedying Fri Jan 20, 2012 11:49 pm ----------------------------------- for line in file("foo.txt"): print line Add one line of code to this such that it prints "Whoops! Empty file." if there's nothing in the file. for line in open("/dev/null"):   print(line) else:   print("null")