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cs_lec_11

#r/lecture

  • Lecture notes: link

Lecture: 10/5

print("Hello world i am cool")

A note on Large Numbers

  • Maximum number of interations that python can run in 1 minute: 10910^9

Staff Solutions

Generators and Generator Functions A generator function is a function that yields values instead of returning them

A normal function returns once; a generator function can yield multiple times

A generator is an iterator created automatically by calling a generator function

When a generator function is called, it returns a generator that iterates over its yields.

Example:

def evens(start,end):
    even = start+start%2
    while even < end:
        yield even
        even+=2
t = evens(4,100000)
t

So for example, in the above example, next(t) will allow the programme to iterate over the yields.

Any code can be put into the function evens. So essentially the yield can allow you to create customised iterators

Only one frame is created for the function call evens. The function execution stops when yield is called, but the function frame is never removed or deleted.

When you call next, then the thing will calculate the next yield

Generator Functions can Yield from Iterables A yield from statement yields all values from an iterator or iterable. ![[chrome_qki2nacJye.png]] All yield functions return generator functions, which essentially are able to generate stuff and can be treated like an iterable.

Example of using yield function at the same time with recursion. ![[WhatsApp Image 2022-10-05 at 1.47.08 PM.jpeg]]

Is definitely possible to construct a recursive function that returns an iterator. Also can iterate through recursive iterator.

Yielding Partitions A partition of a positive integer nn, using parts up to size mm, is a way in which nn can be expressed as the sum of positive integer parts up to mm in increasing order. ![[chrome_R87EoGDgbR.png]] This is Partitioning and then printing it as a string ![[chrome_4nHYJzbpds.png]] This is then doing the same thing with partitions except using the yield functionality. ![[chrome_VFWrePKATh.png]]