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Arevos · May 26th, 2006, 10:18 AM

You can add strings together in the same way you add numbers together:

>>> 1 + 1
2
>>> "a" + "b"
"ab"

The += operator is just a shortcut. The two lines of code below mean exactly the same thing:

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x = x + y
x += y

With regards to the other problem, I'll give you a brief rundown on lists and functions.

You're already a little familiar with list comprehensions. Here's some code which doubles all the numbers in a list:

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numbers = [1, 2, 3, 4, 5]

doubled = [x * 2 for x in numbers]

List comprehensions are essentially a shortcut. This is how to write it out the long way round:

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doubled = []
for x in numbers:
    doubled.append(x * 2)

The above code might take a little explaining. First an empty list is created called "doubled". Then, each number is multiplied by two and added to the "doubled" list. The end result is exactly the same as the list comprehension.

There is also a third way, using the map function:

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def double(x):
    return x * 2
doubled = map(double, numbers)

The map function applies a function to each item in a list.

List comprehensions work well for simple operations that can fit in one line. But more complicated list comprehensions are difficult to create and to work with, so one of the other methods is better used.

What you need to do is output a list that contains both company URLs and whether a company is public or not. I suggest reading up some more on tuples and lists.

May 26th, 2006, 10:18 AM	#199
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	You can add strings together in the same way you add numbers together: (Toggle Plain Text) >>> 1 + 1 2 >>> "a" + "b" "ab" >>> 1 + 1 2 >>> "a" + "b" "ab" The += operator is just a shortcut. The two lines of code below mean exactly the same thing: (Toggle Plain Text) x = x + y x += y x = x + y x += y With regards to the other problem, I'll give you a brief rundown on lists and functions. You're already a little familiar with list comprehensions. Here's some code which doubles all the numbers in a list: (Toggle Plain Text) numbers = [1, 2, 3, 4, 5] doubled = [x * 2 for x in numbers] numbers = [1, 2, 3, 4, 5] doubled = [x * 2 for x in numbers] List comprehensions are essentially a shortcut. This is how to write it out the long way round: (Toggle Plain Text) doubled = [] for x in numbers: doubled.append(x * 2) doubled = [] for x in numbers: doubled.append(x * 2) The above code might take a little explaining. First an empty list is created called "doubled". Then, each number is multiplied by two and added to the "doubled" list. The end result is exactly the same as the list comprehension. There is also a third way, using the map function: (Toggle Plain Text) def double(x): return x * 2 doubled = map(double, numbers) def double(x): return x * 2 doubled = map(double, numbers) The map function applies a function to each item in a list. List comprehensions work well for simple operations that can fit in one line. But more complicated list comprehensions are difficult to create and to work with, so one of the other methods is better used. What you need to do is output a list that contains both company URLs and whether a company is public or not. I suggest reading up some more on tuples and lists.