Rotate (like "clockwise") a singe entry of a tuple in a list of tuples as a Focus - rotation

Question

I have to rotate (like "clockwise") a singe entry of a tuple in a list of tuples. I use this single tuple as a focus.
And when the flag was placed on the end of the list of tuples, it next should be again on the begin.
x = []
x.append(('search','https://www.search.com','1')) # '1' is the focus
x.append(('financials','https://www.stock-exchange.com','0'))
x.append(('fastfood','https://www.burgers.com','0'))
x.append(('tv','https://www.tv.com','0'))
print x
[('search','https://www.search.com','1'),('financials','https://www.stock-exchange.com','0'),('fastfood','https://www.burgers.com','0'),('tv','https://www.tv.com','0')]
What I need to have, is this (abstract displayed)...
- - *
- -
- -
- -
Then I must switch the focus to the "next line"...
- -
- - *
- -
- -
...and later...
- -
- -
- - *
- -
...then...
- -
- -
- -
- - *
...and then this again...
- - *
- -
- -
- -
...and so on.
Sometimes I need to find the focus in my code and extract the data from the first and second entry where the focus (third entry) is currently placed.
With this "one-liner", I can find the focus, and can store all entries to a, b and c:
a,b,c = list(data[[index for (index, a_tuple) in enumerate(x) if a_tuple[2]=='1'][0]])
I like those "one-liners". But changing the focus to the "next line" seems to be not so easy.
newX = [] # Create a new List for x
if '1' in x[len(x)-1][2]: # Determine whether the focus is currently placed on the end, and if Yes, place it to the begin
for b in range(0,len(x),1): # Parse
if b == 0: # Set the focus on the begin
newX.append((x[b][0],x[b][1],'1')) # Set new focus to new list
else: # No focus for all other entries
newX.append((x[b][0],x[b][1],"0")) # Set "no-focus" to all other entries in new list
else: # The focus was not on the end. Where is it?
a = 0 # A little helper
for b in range(0,len(x),1): # Parse again
if '1' in x[b][2]: # Focus found
a = b # Set the current tuple-number to a
break # Already found... don't go on with for/next
for b in range(0,len(x),1): # Parse again
if b == a+1: # Set the new focus on next entry as it was before
newX.append((x[b][0],x[b][1],'1')) # Set new focus to new list
else: # No Focus for all other entries
newX.append((x[b][0],x[b][1],"0")) # Set "no-focus" to all other entries in new list
x = newX # Set x with the new list
del newX,a,b # Save some memory
I managed to do this, but I don't like my code. This task looks so simple that I think there also has to be a "one-liner" for it, something that is embedded internally in Python and that is exactly intended for this. I have v2.7. Anyone an idea?

Answer 1

If I understand you correctly, you want simple modulo (%) operator.
Remove the third item from the tuple, make new variable named selected that will hold the value of selected item:
lst = [
("search", "https://www.search.com"),
("financials", "https://www.stock-exchange.com"),
("fastfood", "https://www.burgers.com"),
("tv", "https://www.tv.com"),
]
selected = 0
def next_selected(lst, cur_selected):
return (cur_selected + 1) % len(lst)
selected = next_selected(lst, selected) # will wrap around
Then getting the selected item is simply:
a, b = lst[selected]

Answer 2

I think I've got it
lst = {
0: ("0","search", "https://www.search.com"),
1: ("0", "financials", "https://www.stock-exchange.com"),
2: ("*", "fastfood", "https://www.burgers.com"),
3: ("0", "tv", "https://www.tv.com"),
}
def next_selected(lst, cur_selected):
return (cur_selected + 1) % len(lst)
for index, key in enumerate(lst): # parse
if lst[index][0] == "*": # found focus
break
lst[index] = "0",lst[index][1],lst[index][2] # delete old focus
selected = index # use index from above parsing
selected = next_selected(lst, selected) # will wrap around
lst[selected] = '*',lst[selected][1],lst[selected][2] # store focus to selected
a,b = lst[selected][1],lst[selected][2] # get values of selected