Introduction to Python

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he uses IPython shell
print(variable)
type(variable)
int()float()str()list()convert to int, etc
y=x+y appends two lists
list_name[3:5]inclusive start exclusive end; 0 indexing; going from end of string last element is -1 indexing
list_name[1][2] for a list of lists you can reference an item inside a sublist
lists y=x different than y=list(x); in the first changing y changes x as well because they point to the same place; in the second changing y does not change x as y is a copy of x and they do not point to the same place
extend a list y=x+["a","b"]; changing an element of y does not change list x
del(x[1]) delete elements of a list
del(areas[-4:-2]) -2 is excluded as it is the end; notice that backwards slice goes still from left to right
Functions
max(), len(), print(), type()
help(function_name) for example help(round) or ?round
methods are functions that belong to objects; objects are floats, strings, lists, etc
in Python everything is an object and has methods associated with it
string methods, list methods for example object.method() list_name.index("mom")=5
Methods are called with the dot notation object.method
packages -> combination of python scripts need to be installed from the terminal,pip3 install numpy then import numpy as np then import package as p or from package import x as y
numpy and math for example; numpy has array which is more useful than list because you can perform calcs, such as multiply the arrays, it will multiply; one array with heights one array with weights, to calculate BMIs you can just do one calculation;
arrays can only contain elements of one type
lists and arrays behave differently
2D arrays
2d_array.shape gives the size of the array say 2x5
2d_array[0][2] or 2d_array[0,2] same thing it returns an element first row and third element in that row
numpy has array and statistics as well
create data using numpy random