#collections.py

#  LIST   []
# ordered (indexes are integers 0-len(list)-1), i.e. subscriptable
# duplicates
# mutable

list_var = []   #empty list.    or:  list()
print("list_var:",list_var)

list_var = [34,'hello',2.718281828, 12345678]   
print("list_var:",list_var)
for item in list_var:
    print(item, end=" ")
print()

for i in range(len(list_var)):
    print(list_var[i], end=" ")
print()

list_var.append('appended item')
print("list_var:",list_var)

print(list_var[::-1])   #returns reversed list
list_var.reverse()      #reverses the list
print(list_var)
#print(sorted(list_var)) #returns sorted list
#list_var.sort()         #sorts the list, items must be same type. random.shuffle(list)
#print(list_var)


#   TUPLE  ()    a list that can't be changed. only count(val) and index(val)
# ordered, i.e. subscriptable 
# duplicates 
# immutable list, immutable items. Can not add, delete, modify items.
#Uses: slightly more efficient than list; so if values not to change, ensure so with tuple
#      function return multiple values as a tuple:   return a,b,c
#      swap:   a,b = b,a
tup = (34,56,23,78,56)
print(tup)
for i in range(len(tup)):    #or:    for t in tup:
    print(tup[i], end=" ")
print()
print(tup.count(56))

print(sorted(tup))    #returns a list


#   SET   {}
# unordered
# NO duplicates 
# immutable elements (but can be deleted and new ones added)
set1 = {"asdf","qwerty","ssss","ert"}
print(sorted(set1))   #returns a list
# cannot be a set of lists.
# test for membership with in.  Faster than list membership check
print('arf' in set1)    


# DICTIONARY  {}   key:value pairs
# unordered (index is key)
# NO duplicate (keys)
# mutable
dict_var = {}   #empty.  or: dict()
print("dict_var:",dict_var)
#     key can be string or numeric
dict_var = {"key1":'val1', "key2":1234, 345:"val3"}    #no concept of order
print("dict_var:",dict_var)
for k in dict_var:    #loop over the keys
    #print(k,dict_var[k], end="   ")    
    print(k,dict_var.get(k), end="   ")    
print()

for k,v in dict_var.items():   #items() returns a list of 2-tuples 
    print(k,v, end="   ")
print()

dict_var["key1"] = 12341234   #replaces existing value
print("dict_var:",dict_var)

dict_var["key3"] = 9999   #new item
print("dict_var:",dict_var)

#typical use: frequency
import random
people = ["alice","bob","carol","ted","zippy"] 
freq_dict = dict([(name,0) for name in people])
print(freq_dict)
for i in range(20):
    freq_dict[random.choice(people)] += 1
print(freq_dict)


keys = ("name","age","city")  # like a record/struct
values1 = ("bob",23,"boston")
values2 = ("alice",24,"naha")
values3 = ("carol",51,"kadena")
d1 = dict([(keys[i],values1[i]) for i in range(len(keys))])
d2 = dict([(keys[i],values2[i]) for i in range(len(keys))])
d3 = dict([(keys[i],values3[i]) for i in range(len(keys))])

dict_list = [d1,d2,d3]

values = [("bob",23,"boston"),("alice",24,"naha"),("carol",51,"kadena")]
dict_list2 = [dict([(keys[i],values[d][i]) for i in range(len(keys))]) for d in range(len(values))]