Needs to be done in Jupyter notebook

 Several of these can be done in one line...

 

1.  Write a list comprehension that produces the following list:

x = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]

 

2. Show a slice notation ( x[:::] ) that selects the following elements, and in this order, from the above array.

y = [15, 14, 13, 12, 11, 10]

 

3. Write a function is_member( p, lst ) that returns True if p is a member of lst, and False otherwise.

 

4. In cryptography, a Caesar cipher is a very simple encryption techniques in which each letter in the plain text is replaced by a letter some fixed number of positions down the alphabet. For example, with a shift of 3, A would be replaced by D, B would become E, and so on. The method is named after Julius Caesar, who used it to communicate with his generals. ROT-13 ("rotate by 13 places") is a widely used example of a Caesar cipher where the shift is 13. In Python, the key for ROT-13 may be represented by means of the following dictionary:

key = {'a':'n', 'b':'o', 'c':'p', 'd':'q', 'e':'r', 'f':'s', 'g':'t', 'h':'u', 
       'i':'v', 'j':'w', 'k':'x', 'l':'y', 'm':'z', 'n':'a', 'o':'b', 'p':'c', 
       'q':'d', 'r':'e', 's':'f', 't':'g', 'u':'h', 'v':'i', 'w':'j', 'x':'k',
       'y':'l', 'z':'m', 'A':'N', 'B':'O', 'C':'P', 'D':'Q', 'E':'R', 'F':'S', 
       'G':'T', 'H':'U', 'I':'V', 'J':'W', 'K':'X', 'L':'Y', 'M':'Z', 'N':'A', 
       'O':'B', 'P':'C', 'Q':'D', 'R':'E', 'S':'F', 'T':'G', 'U':'H', 'V':'I', 
       'W':'J', 'X':'K', 'Y':'L', 'Z':'M'}

Your task in this exercise is to implement an encoder/decoder of ROT-13. Once you're done, you will be able to read the following secret message:

Pnrfne pvcure? V zhpu cersre Pnrfne fnynq!

Note that since English has 26 characters, your ROT-13 program will be able to both encode and decode texts written in English.

Show that this is true.

 

5. Meet the string s:

s = 'j#kxtovtwa#cpgj#ia#razda#qcf#bhw#ztcgotlzs#ee#vjmkexiube#tszm#g#'

Write a function that splits the string on #s, then returns a list of integers which are the lengths of the random strings between #s.

i.e.

getlens(s) = [1, 8, 4, 2, 5, 3, 3, 9, 2, 10, 4, 1, 0]