Dict list question

[Layvian]

I was attempting to change a value within a dictionary list via a list variable. However it does not change. Is this a feature of a Dictionary list or am I doing something incorrect? Thank you in advance for any assistance.

user_id = ['username', 'password', 'first_name', 'last_name', 'email', 'active']
 
account = {'username':user_id[0], 'password':user_id[1], 'first_name':user_id[2],
         'last_name':user_id[3], 'email':user_id[4], 'active':user_id[5]}
 
run = 1
 
while run == 1:
 
    user_id[1] = raw_input('Please enter a new password: ')
 
    if user_id[1] is account['password']:
        print "Password Successfully Changed!"
        run = 0
 
    else:
        print "Password Change FAILED, please try again"
 

Output:
Password Change FAILED, please try again

[bvdet]

When the assignment to account is made, user_id[1] is evaluated as a string and is not a reference to user_id. Why do you need the list user_id anyway?

[Layvian]

I really do not have to use it. Really just curious more then anything. I noticed when I added a print syntax it showed me the correct value. I figured if anything it had to be how the value was stored. Thank you for your assistance.

[dwblas]

Strings are immutable so you would have to use a container that is mutable, like a list, to have the dictionary point to the same memory location (otherwise the dictionary stays with the original entry). Also "is" is different from "==", but would work in my code (not in yours) because they both point to the same object.

user_id = ['username', ['password'], 'first_name', 'last_name', 'email', 'active']
 
account = {'username':user_id[0], 'password':user_id[1], 'first_name':user_id[2],
          'last_name':user_id[3], 'email':user_id[4], 'active':user_id[5]}
 
run = 1
while run == 1:
 
     user_id[1][0] = raw_input('Please enter a new password: ')
     if user_id[1] == account['password']:
         print "Password Successfully Changed!"
         run = 0
 
     else:
         print "Password Change FAILED, please try again" 

a="abc"
b="abc"
print a, b, a is b
c="ab"
print a, c, a is c
c += "c"
print a, c, a is c, a == c 

[Layvian]

So in order to get the desired results I needed to create a 2D array/list which is considered a mutable container?

[dwblas]

The mutable container has to be whatever you want to link, so both reflect the change. So if you want to change a certain element of a list, then that element has to be a sub-list and not a string, which is different from a 2D array as the rest of the elements are still strings.

user_id = ['username', 'password', 'first_name', 'last_name', 'email', 'active']
 
account = {'username':user_id[0], 'password':user_id[1], 'first_name':user_id[2],
          'last_name':user_id[3], 'email':user_id[4], 'active':user_id[5]}
 
print id(account['password']), id(user_id[1])  ## they are the same
user_id[1]="new"
print id(account['password']), id(user_id[1])  ## different
 
user_id = ['username', ['password'], 'first_name', 'last_name', 'email', 'active']
 
account = {'username':user_id[0], 'password':user_id[1], 'first_name':user_id[2],
          'last_name':user_id[3], 'email':user_id[4], 'active':user_id[5]}
 
print "-"*30
print id(account['password']), id(user_id[1])  ## they are the same
user_id[1][0]="new"
print id(account['password']), id(user_id[1])  ## still the same