Given k and either a block of text, or a 2d array that the inner arrays may have unequal lengths (that resembles a block of text), rotate every character or element in the k-th column up or down to the next position that exists.

Example

Rotate the 20th column of the following text (1-based):

A line with more than k characters.

A longer line with more than k character.

A short line.

Rotate here: ------v--

This is long enough.



This is not enough.

Wrapping around to the first line.

Output:

A line with more thtn k characters.

A longer line with aore than k character.

A short line.

Rotate here: ------m--

This is long enoughv



This is not enough.

Wrapping around to .he first line.

Rotating the k-th column of the same input where k > 35 would yield the input text unchanged.

Rules

• You may use raw text, an array of lines, a 2d array of characters, or any reasonable format to represent the data. You may also use data types other than characters.


• The number of possible values of the data type of the elements must be at least 20 if your code length depends on it, otherwise at least 2. This could be a subset of the characters or other values supported in the native type.


• Spaces and any kind of null values are just normal values (if you allow them in the input).


• 
  k could be 0-based or 1-based. It is guaranteed to be inside the longest line in the input (implying the input has at least one non-empty line).


• You may choose whether it rotates up or down.


• Either just rotate one position, or rotate n positions where n is a positive integer given in the input.


• Shortest code wins.

Python 2, 111 110 109 99 98 96 bytes

a,n=input()

x=[l[n]for l in a if l[n:]]

for l in a:print l[:n]+(l[n:]and x.pop(x>x[:1])+l[n+1:])

Try it online!

Takes input as a list of lines and 0-index column, and prints result.

Column is rotated up 1.

_{-11 bytes, thanks to Jo King}

05AB1E, 21 bytes

ʒg‹}U¹εXyk©diX®<èIèIǝ

Can definitely be golfed some more..

0-indexed; input and output both as a list of strings.

It rotates down like the example, but < can be replaced with > to rotate up instead.

Try it online (footer joins the list by newlines, remove it to see the actual list output).

Explanation:

ʒ  }             # Filter the (implicit) input-list by:

 g               #  Where length of the current string

  ‹              #  is larger than the (implicit) input-integer

    U            # Pop and store this filtered list in variable `X`

¹ε               # Map over the first input-list again:

  Xyk            #  Get the index of the current string in variable `X`

     ©           #  Store it in the register (without popping)

      di         #  If the index is not -1, so the current string is present in variable `X`

        X®<è     #   Get the (index-1)'th string in variable `X`

            Iè   #   Get the character at the index of the input-integer

              Iǝ #   And insert it at the index of the input-integer in the current string