A first glance at Python and Jupyter

1. Hello World



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print('Hello World')

2. Print the 'help' for a particular function (try also using the IPython shell)



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help(random)

Some useful to get help in Jupyter Notebook:

Hold Shift + Tab over a function inside a code cell.
Function name with a question mark after it.



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random.random?

3. IPython Magic Commands

The magics we are going to use the most: %%time, %%timeit, and %matplotlib. More info about magics here.



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%lsmagic

3. Importing Python modules

To use an external module in Python you can import it into your script by using the import statement.



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import math #imports the whole module. It requires to use the prefix "math." before calling each function
from math import * #imports all functions and variable within the current namespace (it does not require to use the prefix)
from math import cos, pi #imports only the specific functions and variables listed

Try using the different import options to describe the following expression:

    x = cos(2 *pi)



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x = math.cos(2 * math.pi)
x = cos(2 * pi)
print(x)

Functions

1. Define a function that returns the sum of two random numbers



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import random



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def sumTwoRandomNumbers():
    a = random.random()
    b = random.random()
    c = a+b
    print ('a: ', a, ' b: ', b)
    print(type(a))
    return c



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sumTwoRandomNumbers()

2. Define a function that returns the sum of two given numbers



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def sumTwoGivenNumbers(a, b):
    c = a+b
    return c



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sumTwoGivenNumbers(23, 7)

3. Define a function that returns the sum of multiple given numbers



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def sumMultipleNumbers(*args):
    c = sum(args)
    return c



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sumMultipleNumbers(1,2,3)

4. Define a function that returns sum or the average of a variable set of numbers



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def opMultipleNumbers(*args, **kwargs):
    if kwargs.get("operation") == "sum":
         c = sum(args)
    if kwargs.get("operation") == "avg":
         c = sum(args)/len(args)
    return c



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opMultipleNumbers(1,2,3,4,operation="avg")

Exercise

1. Define a function that returns a list of numbers that sum up to 1

Generate a list of random numbers
Sum up all the numbers in the list
Take each number in the initial list and divide it by the sum of all numbers
Print the new list
Sum up all the values in the new list. It should sum up to 1



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randomNumbers = [random.random() for i in range(1,10)]
s = sum(randomNumbers)
r = [ i/s for i in randomNumbers ]
print (r)
print(sum(r))









    



[0.02770880546317565, 0.15676907789403854, 0.002290709060239855, 0.014333832439627468, 0.31363690061092536, 0.17574429881851422, 0.04481370109223432, 0.14866960184950107, 0.11603307277174349]
1.0

Useful Resources

https://www.dataquest.io/blog/jupyter-notebook-tips-tricks-shortcuts/



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