explain slice assignment to newb

[Andrew]

please explain this behavior to a newb:

>>a = [1,2,3,4]
>>b = ["a","b","c" ,"d"]
>>a

[1, 2, 3, 4]

>>b

['a', 'b', 'c', 'd']

>>a[0:2]

[1, 2]

>>a

[1, 2, 3, 4]

>>b[2:4]

['c', 'd']

>>a[0:2] = b[0:2]
>>b[2:4] = a[2:4]
>>a

['a', 'b', 3, 4]

>>b

['a', 'b', 3, 4]

>>>

[Terry Reedy]

Re: explain slice assignment to newb

Andrew wrote:

please explain this behavior to a newb:

Read the section on sequence slicing in the Library Reference. Use the
interactive interpreter or IDLE to perform experiments, like you did,
until you understand to your satisfaction.

[Stephen Horne]

Re: explain slice assignment to newb

On Sat, 20 Sep 2008 14:20:20 -0700 (PDT), Andrew <aetodd@gmail.c om>
wrote:

>please explain this behavior to a newb:
>

>>>a = [1,2,3,4]
>>>b = ["a","b","c" ,"d"]

>>>a[0:2] = b[0:2]

The slice [0:2] represent positions 0 <= x < 2
Replaces the [1, 2] from [1, 2, 3, 4] with ['a', 'b']
Result: a = ['a', 'b', 3, 4]

>>>b[2:4] = a[2:4]

The slice [2:4] represent positions 2 <= x < 4
Replaces the ['c', 'd'] from ['a', 'b', 'c', 'd'] with [3, 4]
Result: b = ['a', 'b', 3, 4]

>>>a

>['a', 'b', 3, 4]

>>>b

>['a', 'b', 3, 4]

Correct