# exp3.py3   example file  more complete structure, list, arrays, matrix
import math
from numpy import array  # for vector and matrix

def main():
  print("exp3.py3 running")
  a_list=[7, 7.25, "abc"]  # any types
  print("a_list=",a_list)
  print("a_list[2]=",a_list[2])  # selecting item 2, start with 0
  a_list.append("def")     # append to end of list
  print("append=",a_list)
  del a_list[1]            # delete a selected item
  print("delete=",a_list)
  print("len(a_list)=",len(a_list)) # get the length of a list
  print(" ")

  a_tuple=2, 3, 5, 7   # can not modify  all same type
  b_tuple=(2, 3, 5, 7) # same data as above   all same type
  print("a_tuple=",a_tuple)
  print("b_tuple=",b_tuple)
  print("b_tuple[2]=",b_tuple[2]) # select item 2 for printing
  # b_tuple[2] = 9     # no modify selected item
  print(" ")

  dict={1:'a', 2:'b', 3:'c'} # dictionary key : value
  print("dict=",dict)
  dict[5]='e'
  print("dict[5]=e",dict)
  print("dict[3]=",dict[3]) # look up by key
  print(" ")

  z=range(5)            # zero based, length 5, no 5
  print("range(5)=",z)
  z=range(1,5)          # 1 based, length 4, no 5
  print("range(1,5)=",z)
  z=range(1,7,2)        # step size 2, no 7
  print("range(1,7,2)=",z)
  print(" ")

  Y = array([0.0 for i in range(4)]) # initialize to zero
  print("array([0.0 for i in range(4)])=")
  print(Y)
  A = array([[1.0 for j in range(4)] for i in range(3)]) # initialize to 1
  print("array([1.0 for j in range(4)] for i in range(3)])=")
  print(A)
  A[2,3] = 2.0
  print("A[2,3] = 2.0")
  print(A)
  print(" ")
  
if __name__ == '__main__':
  main()