Python Tutorial: Arrays & plotting

Key Takeaways

you've learned about basic Python data structures but coming from MATLAB you must be wondering where the matrices and plotting functions are in Python MATLAB like matrices are called arrays arrays are implemented using the numpy package which is short for numerical Python arrays are the foundation for all data science in Python like matlab's matrices num pies arrays can have one two three or more dimensions and every element in the array must be of the same type all integers are all floats for example there are some practical differences however particularly in how you access data stored in numpy arrays first is the syntax for indexing into the array in MATLAB you are used to using parentheses however in Python we use square brackets for indexing in this example I have a numpy array in the variable ARR and you can see that I'm using square brackets with an integer for the index I want to get out of the array the second big difference is that indexing itself in Python the index 2 will return the third element in the array this is because python uses zero indexing that is the first element is accessed with 0 the second with 1 the third with 2 and so on one way to think about it is that if matlab is an american elevator where the ground floor starts with 1 python is a european elevator where one denotes the level above the ground floor this is likely very unintuitive coming from MATLAB but with practice it's easy to get used to it the final element in an array can be accessed with its index from zero or negative one which works like matlab's end for visualizing your data there are multiple packages to choose from in Python the most popular and the one we are going to use is called matplotlib lucky for you matplotlib was designed to work similarly to plotting in MATLAB so it shares many of the functions for plotting and customizing pots that you are familiar with first the package needs to be imported most plotting functions live in map plot lives PI plot module which is typically imported to the variable P LT like so once imported the PI plot module contains many functions that work similarly to their MATLAB counterparts figure creates a new figure to plot in plot creates line plots X label and y label add labels to the X and y axes respectively importantly we need to explicitly call show to display any plots that we create now that you know how to use numpy arrays to store data and map plot libe to make plots you're ready to