#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed Jun 14 14:49:29 2023

@author: richardson
"""

# manipulation with arrays

c=[3,"hilfr",3.7] # c is a list
print(c)

for b in c: # note flexibility of for statement
    print("The type of "+str(b)+" is "+str(type(b)))

print(c[1]) # c[0] is the first element of the list, 
# c(1) is the second element, etc.

# making a list
cl = [] # an empty list
for j in range(2,40):
    cl += [j**2] # ** means ^ in python
    # The ^ is a bitwise operation
    # A += B means A = A+B
    # [1,2,3]+[11,2]=[1,2,3,11,2]
    # so + for lists is concatenation
print(cl)

# shortcut to the above: list comprehension

cl2 = [j**2 for j in range(2,40)]
print(cl2)

cl3 = [j**2 for j in range(2,40) if j%7!=0]
# list of squares starting with 2^2 and ending with 39^2 but
# not including multiples of 7
print(cl3)

# we can make matrices as lists of lists
A = [[2,3],[-1,7]]
print(A)
print(A[1][0]) # this is the second row, 1st column of the matrix

A+=[[11,17]]
print(A)
print(A[2][0])