Item assignment to tuples-CodePudding

I am trying to change the value of a particular element of a tuple of tuples. Here is the code:

y=((2,2),(3,3))
y[1][1]=999
print('y: ',y)

TypeError: 'tuple' object does not support item assignment

I understand that Tuples are immutable objects. “Immutable” means you cannot change the values inside a tuple. You can only remove them. I was wondering if there is a workaround? I cannot create a list of lists for y because I am using y as a key in a dictionary later.

CodePudding user response：

If you don't expect the modified value of y to point to the same dictionary entry, you could convert to a list of lists, modify that and then convert back to tuples. For example:

d = { ((2,2),(3,3)) : 'old', ((2, 2), (3, 999)) : 'new' }
y = ((2,2),(3,3))
print(d[y])
z = list(list(a) for a in y)
z[1][1] = 999
y = tuple(tuple(a) for a in z)
print(d[y])

Output:

old
new

CodePudding user response：

The workaround would be to convert it to the list, make changes, and then convert to the tuple again, if you need to use the tuple later as a key to a dictionary. There is no way to directly change the values.

y=((2,2),(3,3))
y = list(y)
for i in range(len(y)):
    y[i] = list(y[i])

y[1][1] = 999

for i in range(len(y)):
    y[i] = tuple(y[i])
y = tuple(y)

print('y: ',y)

CodePudding user response：

You can't change the values of tuples because they are constant. But, you can convert it back to a list to be changed.

Code:

x=((2,2),(3,3))
y = list(x)
print(y)
for i in range(len(y)):
    y[i] = list(x[i])
y[1][1]=999
print(y)