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PYTHON AS A CALCULATOR

FOR A FULL LIST OF MATHEMATICAL OPERATIONS IN PYTHON SEE: https://www.tutorialspoint.com/python/python_basic_operators.htm This will be useful later, so only skip it if you know it already

QUESTION 1

3, 56, 6, 3, 44, 5, 6, 7775, 32353, 34534, 345
- For the numbers above find:
  - the largest
  - the smallest
  - the sum of all the numbers
 
- Use the statistics module to compute:
  - the mean
  - the median
  - the variance
  - and standard deviation

- Use the math module to calculate the following:
  - the value of pi rounded down to the nearest whole number
  - the value of pi rounded up to nearest whole number
  - the square root of pi
  - the log of pi

import math 
pi = math.pi
- Calculate: 
  - pi squared divided by pi cubed
  - generate some random numbers
  - what is sine(pi/2), sine(pi/4), sine(pi/8)
  - if the result is in radians, convert it to degrees
  - cast your result from a float into a string

VARIABLE ASSIGNMENT

QUESTION 2

Complete the following

- assign the number 3 to a variable called width, and the number 110 to a variable called height
- calculate the area and assign it to a new variable called area
- turns out you got the width and height mixed up, see if you can swap them without re-declaring the width and height variables
- assign the width and height variables in a single statement

CONTROL FLOW - USING STATEMENTS

QUESTION 3

Complete the following:

- write a simple for loop that counts up to 10 and prints the value
- use an if statement to print 4 if the value is 4
- add an else clause to print 'the number is not 4' when it is not 4
- use an if statement to print if the value is anything other than 4
- rewrite this using a while loop (HINT: try out using the += operation)

STRING MANIPULATION

IMPORTANT: if you are uncertain what is meant by built-in method, have a look here (https://docs.python.org/3/library/stdtypes.html) # at the different functionality that is built-in to each data type

QUESTION 4

secret_message = 'S1R3E2!!3@4T2R3AT23@@!S2Y3pbO1T3!@@!!4b1E@M134O13C1L3@@Ew41@23!!'

For the secret_message variable:

- remove all digits and special characters from the secret message
- replace all every letter b with an empty space 
- if you wrote your answer as a loop, try with a list comprehension
- reverse the capitalisation
- reverse the order of the letters
- use built in string methods to do the following

Do what the strings tell you do do:

s1 = '              please remove the space around me           '
s2 = '               please remove the space on my right           '
s3 = 'please add the same number of spaces on my left as on my right             '
- combine strings s1 and s2
    - do it with and without using built-in string methods

- for a and b (below), compute the following:
    - a + b
    - a * b

a = '3.1' 
b = '22.323'    
- if your result is just one long string, try to cast a and b into integers and try again

- replace the {}s below with the value of pi using string methods, for 0, 2 and 5 decimal places respectively

print('the value of pi is: {}, {}, {}')
- print the following string: '23\42\34\23\\\//'
- think about what is going on, google it and see why it doesn't work as expected

WORKING WITH TEXT FILES

QUESTION 5

Complete the following:

- load the example dataset '/resources/strings_example_1.txt'
- change the vowels back to normal characters
- locate the hidden substring (HINT: the it starts and ends with __)
- remove this substring and save the modified text in a new variable. Show that this is no longer the same as the original
- find the counts of each letter in the text such that:
    - 'aaAabb dddDD hhcc' >>> [('d',5), ('a',4), ('b',2), ('c',2), ('h', 2)]
- make a separate list for alphabetical, numeric and special characters
    - HINT: you may want to use sets to solve this

QUESTION 6

Complete the following:

- load the dataset '/resources/strings_example_2.txt'
- clean the text and create a flat list containing every word    
- produce a dictionary containing each word as a key and that word's count as the value
- find the average length of the unique words in the text
- find the weighted average word lengths

QUESTION 7

Complete the following:

- modify this code to ensure that email addresses follow the following rules:
    - all lower case
    - takes the first letter of the first name and combines with with the whole last name
    - it removes any extra spaces/unwanted characters
    - it creates multiple email addresses for all the groups in groups_that_need_emails

first_name = input('please enter your first name:')
surname = input('please enter your surname:')
email = first_name + '.' + surname + '@pystarters.co.uk'

print(email)

groups_that_need_emails =  ('pystarters', 'pyclub', 'UCL', 'SWC', 'gatsby')

APPLIED QUESTION - DEALING WITH LOTS OF FILES

QUESTION 8

You have a folder of serial two photon microscope images ('/resources/tissue_vision_files/') containing many (empty) .tif images. The image filenames are of the format mmddyyyy-hhmm-image_index-channel_number.tif

- generate a list of all the file names
- sort the lists in a human readable way 
    - HINT: the file names are not zero-padded, which messes up the sorting
- separate images 100-200 into three separate lists, one for each channel
    - insert 'modified' into all file names: e.g. '02162018-1620-0_01_modified.tif'
    - do not include any files that end with .txt
- save these files to separate folders
- what do you think is wrong with these file names? what would you do to make them nicer?