Is there an "extensible 2D table" data structure?

Question

Algorithms

I want such data structure: the expanded/contracted two-dimensional table.

That is: we have, for example, a 5×5 table, and we add a row to it from above, and it becomes 6×5. And then we add two columns to the right, and it became 6 × 7. And then we remove two lines from the bottom, and it became 4 × 7.

Expanding and contracting is possible only from the edges - that is, you cannot remove a row or column from the middle, and you cannot add anything to the middle.

Tell me in which direction to move?

Answer 1

Until stopped on such a mechanism.
There are two one-dimensional arrays - the table of contents of the rows and the table of contents of the columns, two one-dimensional arrays - the involvement of rows / columns, and a two-dimensional array - the buffer.
a[i,j] := buffer[rowIndex[i−i0], colIndex[j−j0]]
If rowIndex[i−i0] has an unused marker, find the unused row and add it to the table of contents.
To less re-allocate memory, re-allocation occurs in impulses and with a margin. For example, we want 20 lines, and we allocate 30 at once.
Such an array can only expand, but this is enough for me.

Answer 2

you can not be limited to 2D
Alternatively, look at the implementation of ndarray in Numpy.
Partially described here (in English)
The data is stored in a buffer - an array type in C. And there is metadata describing the "view" of this buffer.
When the form changes, a new metadata object is created, without changing the data itself.
But the topic of insertion is not disclosed here, how it changes the size of the buffer - create a new one or expand the old one. At the end, or stuffed into lines.

Answer 3

The boxed solution is a hash table. Where the key is the coordinates of the cell and the value is what you put in the cell.

Answer 4

No, there is no such thing in standard libraries, at least I don't know about such ones.
You can implement yourself:
1) Using a linked list;
2) On an array, with pre-allocated memory, with the addition of elements to the center. Further expand in the direction that is required.

Answer 5

Matlab does this automatically for a matrix (you can even rearrange rows or columns in any order). It is based on Java.