MOD_5_NOTES-Strings_Functions.txt

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Functions and Strings
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Strings are iterable primitives and can behave like lists, via their inbuilt methods, however strings are immutable,
so you can't edit them. Can be replaced in memory, but not mutated.
**help(str)** provides all methods

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Format strings
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- A clean formatting method for dynamic values, to avoid concatenation. 
**Can pass in numerical index of arguments!**

name = 'Taddes'
age = 30

'My name is {} and I am {} years old'.format(name, age)

**Can pass in numerical index of arguments!**
'My name is {0} and I am {1} years old. I mean it, I am really {1}'.format(name, age)

**Can reference arguments by name
' I am {name} and am {years} years old'.format(name=name, years=age)

**Format the output of strings**
--Many methods exist to modify the output format of a string--
funds = 150.97524

'Funds: {:f}'.format(funds)
# 'Funds: 150.972300'

'Funds: {:1f}'.format(funds)
#'Funds: 151.0'

'Funds: {:10f}'.format(funds)
#'Funds:          151.0'

*Shorthand PY3*
f'Funds: {funds}'

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Map Function
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*NOTE: List comprehension faster, and preferred
Allows you to pass in a function to mutate values within a lists

my_list = [1,2,3,4]
def mult(el):
    return el * 2

list(map(mult, my_list))
# [2,4,6,8]

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Lambda Functions
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* A more efficient means of creating a simple function that has only one argument and returns a value.
A one-off, anonomyous function

lambda (to invoke function)
argument list, comma seperated args
:
expression body

list(map(lambda el: el * 2, simple_list))

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Reducing Lists
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*Reduce/convert all values of a list to a single value (Ex. Add, multiply, etc.)
-Has current value of the list
-has Last result, which is needed to reduce (value previous)