Test Your Skills: Python Thread

[wtd]

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.

code:

>>> ', '.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]

Given the snippet of code from the interactive interpreter:

code:

>>> foo() bar >>>

Write the code which makes this possible. Your code may not include any kind of input/output operation.

[wtd]

wtd wrote:

Given the snippet of code from the interactive interpreter:

code:

>>> 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:

Python:

class foo(object):    def __repr__(self):       return "bar"

[[Gandalf]]

I have not looked into Python too much, so forgive any mistakes, but...

Python:

def foo():       return "bar"

Could you not just do that?

[wtd]

[Gandalf] wrote:

I have not looked into Python too much, so forgive any mistakes, but...

Python:

def foo():       return "bar"

Could you not just do that?

In that case, what'd you'd see would be:

code:

>>> foo() "bar" >>>

[Hikaru79]

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).

Python:

Dict(foo=5, bar=12, foobar=9)

I hope this isn't too easy, hard, pointless, etc

[wtd]

Python:

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]

if os.path.getsize("foo.txt") = 0 : print "empty file"

[wtd]

Not what I was looking for.

What I am looking for is part of the loop.

[bugzpodder]

hint

[wtd]

See the Tutorial under the Documentation section on python.org. It has the answer.

[Roman]

wtd @ Thu Sep 29, 2005 2:54 pm wrote:

Challenge #1: Join

code:

>>> ', '.join(['1', '2', '3']) '1, 2, 3'

I'm very new at this, but couldn't you just do

code:

def joinFctn(sep, lst):     print sep.join(lst)

P.S. Only three years late x_x

[[Gandalf]]

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:

Python:

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]

Your mixing up the challenges Gandalf. One of the challenges, you cannot return anything. The other you can.

[SS_198]

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 <