I found that python doesn't have C style for loop:
for (var;condition:increment)
For a simple for loop, I can use
for i in xrange(number):
to produce
for (i;i<number;i++)
however, if i have
for (i = 2; an_array[i - 2] < number; i++)
how can I produce it in python?
thanks
You could
iterate over that array and use one of the neat functions in itertools, such as takewhile():
for item in takewhile(lambda i: i < number, array[2:]):
# do stuff
This takes values from the given iterable (here: an array) until (resp. while) its contents meet a certain condition.
Here, item is the content of the respective array entry. If you really need the indexes, you can combine it with enumerate():
for index, item in enumerate(takewhile(lambda i: i < number, array[2:])):
# do stuff
But this index is off by 2, because it counts the items passed through; as you start with array[2:] you'll have to add 2 in order to access the right part of the array.
Use a while loop:
i = 2
while (array[i-2] < number):
# do stuff
i += 1
enumerate gained a starting index value (start=0) in Python 2.6, which makes the second version a bit nicer: for index, item in enumerate(takewhile(lambda i: i < number, array[2:]), start=2):. Note that slicing the array makes a copy; if the array tends to be very large and efficiency is important you could use itertools.islice as well. But I'd probably just start with method 2, the while loop, for readability. :-)You can use the following:
for i in xrange(2, number):
# Whatever
When xrange takes 2 parameters, it creates a range from the first value to the last value. Note that the first value is included while the last value is not.
EDIT: If you're working with an array, Tim Pietzcker's method is the way to go. I just gave this method to provide a convenient counterpart.
an_array[i - 2] < number breaking condition?