[Python] How can I wrap a string or an array around and slice the wrapped string or array in...

How can I slice a string or an array from a point to another point with an end between them?

Essentially, we want to do something like this,

n = whatever we want
print(string[n-5:n+6])


The above code may look normal. But it doesn't work near the edges (near the beginning of the string/array or the end of the string/array). Because Python's slicing doesn't allow slicing through the end of the array and continuing from the beginning. What if n is smaller than 5 or length of string longer than n+6?

Here's a better example, consider that we have

array = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k']


We want to print an element with its nearest two neighbors in string for all elements in an array

print("Two neighbors:")
for i, x in enumerate(array):
print(array[i-1] + array + array[(i+1)%len(array)])


Output:

Two neighbors:
kab
abc
bcd
cde
def
efg
fgh
ghi
hij
ijk
jka


So far so good, let's do it with four neighbors.

print("Four neighbors:")
for i, x in enumerate(array):
print(array[i-2] + array[i-1] + array + array[(i+1)%len(array)] + array[(i+2)%len(array)])


Output:

Four neighbors:
jkabc
kabcd
abcde
bcdef
cdefg
defgh
efghi
fghij
ghijk
hijka
ijkab


You can see where this is going, as the desired number of neighbors grow, the number of times we must type them out one by one increases.

Is there a way instead of s[n-3]+s[n-2]+s[n-1]+s[n]+s[n+1]+s[n+2]+s[n+3], we can do something like s[n-3:n+4]?

Note that s[n-3:n]+s[nn+4)%len(s)] doesn't work at the edges.

NOTE:

For the particular example above, it is possible to do a 3*array or add a number of elements to the front and to the back to essentially "pad" it.

However, this type of answer cost a bit of memory AND cannot work when we want to wrap it many folds around.

Consider the following,

# len(string) = 10
# n = 0 or any number we want
print(string[n-499:n+999])


If the start and end indices can be flexible instead of mirroring each other(eg. string[n-2:n+9] instead of string[n-3:n+4]), it is even better.

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