Rename dictionary keys/values in python

Question

What I'm trying to do is this. I have a dictionary laid out as such:

legJointConnectors = {'L_hip_jnt': ['L_knee_jnt'], 'L_knee_jnt': ['L_ankle_jnt'], 'L_ankle_jnt': ['L_ball_jnt'], 'L_ball_jnt': ['L_toe_jnt']}

What I want to be able to do is iterate through this, but change the L_ to R_. Here's how I tried to do it, but it failed, because it's expecting a string and I'm passing it a list.

for key, value in legJointConnectors.iteritems():
    if side == 'L':
        cmds.connectJoint(value, key, pm=True)
    else:
        key = re.sub('L_', 'R_', key)
        value = re.sub('L_', 'R_', value)
        cmds.connectJoint(value, key, pm=True)

Obviously I'm not doing this correctly, so how can I do this? Should I create an empty dictionary and populate it with the necessary data on the fly? Or is there a better way to do it? Thanks for the help!

[edit] The if side == 'L' is testing to see what side we're currently working on. This script is being used within Maya, so I'm creating joints based on the side and then connecting them.

Based off of KennyTM's suggestion I tried this:

for key, value in legJointConnectors.iteritems():
        if side == 'L':
            cmds.connectJoint(value, key, pm=True)
        else:
            for v in value:
                value = 'R_' + v[2:]
                for k in key:    
                    key = 'R_' + k[2:]
                print key
            print value

but while it returns the correct key, the value returns as R_

Answer 1

Do the substitution on every element of the list then.

for key, value in legJointConnectors.iteritems():
    if side != 'L':
        key = 'R_' + key[2:]
        value = ['R_' + v[2:] for v in value]
    cmds.connectJoint(value, key, pm=True)

(BTW, it is better to use v.replace('L_', 'R_'), or just 'R_' + v[2:] to perform the replacement then using regex for this.)

Answer 2

You could create a new dictionary:

remap = lambda x: re.sub('L_','R_', x )
dict( remap( key ), [remap( value[0] )] for key, value in mydict.iteritems() )

Answer 3

I would have suggested { key.replace('L_', 'R_'): [value.replace('L_', 'R_') for value in values ] for (key, values) in legJointConnectors.iteritems() } (if you use a python version that lacks dict comprehensions, you can use dict( (key..., [value...]) for ...) instead), but the if side == 'L' part confuses me... what does it do?