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Best python learning resource on the internet, by FAR

http://xoxohth.com/thread.php?thread_id=3675303&mc=26&am...
Just relaxing before noraebang tonight (socatoa)
  07/14/17
That was very helpful ty. I take it "map" is ju...
shortquotemo
  07/14/17
Yes, it is a built-in. 0xA0a22836Dce4Eb20C73Ff15520F8abE7...
Just relaxing before noraebang tonight (socatoa)
  07/14/17
1. names = ["Alice", "Bob", "Carol...
--___--
  07/15/17
In the future you should indent. 1. Good work. An even...
Just relaxing before noraebang tonight (socatoa)
  07/15/17
1. ty 2. lol i didnt know that built in feature existed 3....
--___--
  07/15/17
That will be 0.05 ETH 0xA0a22836Dce4Eb20C73Ff15520F8abE7F...
Just relaxing before noraebang tonight (socatoa)
  07/15/17
lol fma
--___--
  07/15/17


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Date: July 14th, 2017 11:52 PM
Author: Just relaxing before noraebang tonight (socatoa)

http://xoxohth.com/thread.php?thread_id=3675303&mc=26&forum_id=2#33777686

socatoa's lessons

(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33777921)



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Date: July 14th, 2017 11:55 PM
Author: shortquotemo

That was very helpful ty.

I take it "map" is just a built in python function/method?

Haven't had a chance to finish reading but will do so soon

(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33777941)



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Date: July 14th, 2017 11:56 PM
Author: Just relaxing before noraebang tonight (socatoa)

Yes, it is a built-in.

0xA0a22836Dce4Eb20C73Ff15520F8abE7FBe8bA47

Understanding map is a key conceptual building block to understanding comprehensions, which are the killer feature of Python.

(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33777949)



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Date: July 15th, 2017 12:51 AM
Author: --___--

1.

names = ["Alice", "Bob", "Carol"]

def length_string(x):

return len(x)

result = map(length_string,names)

print(list(result))

2.

numbers = [ [1, 2, 3], [4, 5, 6], [7, 8, 9] ]

def sum_nums(x):

return x[0]+x[1]+x[2]

result = map(sum_nums,numbers)

print(list(result))

3.num = [2, 3, 4, 5, 6, 7, 8, 9, 10]

def check_prime(x):

y = 2

if x <= 3:

return "true"

while x / y >= 2:

if x % y == 0:

return "false"

y = y + 1

return "true"

result = map(check_prime,num)

print(list(result))



(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33778329)



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Date: July 15th, 2017 1:05 AM
Author: Just relaxing before noraebang tonight (socatoa)

In the future you should indent.

1. Good work.

An even better solution would be map(len, names).

No need to write a wrapper function around len, when there is already a built-in len function that does the job itself!

2. A better solution than yours:

numbers = [ [1, 2, 3], [4, 5, 6], [7, 8, 9] ]

def sum_nums(lst):

... return sum(lst)

Your solution would only add arrays of length 3.

Or better yet, just write: map(sum, numbers)

No need to define a sum function when you can just leverage the built-in one!

3.

-- You should use the boolean types True and False, since that is what is required by the result.

-- According to your prime function, 1 and all negative numbers are prime. That might seem like an insignificant mistake, but it would likely come back to haunt you if, for example, you wrote some recursive function that relied on checking results for smaller primes.

--Your solution is extremely inefficient in doing a division in the "while loop" check. Division is hundreds of times more expensive than addition or multiplication for computers. A far more efficient check would be "while x >= 2*y"

--Your solution is a little inefficient in that you can stop once y exceeds sqrt(x) in value.

def check_prime(x):

....y = 2

....if x <= 3:

........return True

....while x / y >= 2:

........if x % y == 0:

............return False

........y = y + 1

....return True

(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33778419)



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Date: July 15th, 2017 1:09 AM
Author: --___--

1. ty

2. lol i didnt know that built in feature existed

3.a. i was going to google how to output boolean but was lazy lol

b. prime #s was one of the few euler type problems that i am good with just banging it out but u are 100% correct

tyty for the feedback. great lesson man.

(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33778441)



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Date: July 15th, 2017 1:08 AM
Author: Just relaxing before noraebang tonight (socatoa)

That will be 0.05 ETH

0xA0a22836Dce4Eb20C73Ff15520F8abE7FBe8bA47

(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33778434)



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Date: July 15th, 2017 1:09 AM
Author: --___--

lol fma

(http://www.autoadmit.com/thread.php?thread_id=3675368&forum_id=2#33778443)