Conditional addition of matrix rows?

My data matrix consists of 54 coloumns and 186 rows. The values in the first column varies from 0 to 6. I need to add the rows of remaining columns conditionally.

For example, I set a window of 1 for addition of rows 6-5, 5-4, 4-3, 3-2 and so on.

for first window (6-5), there is only one row ...

for second window (5-4) ... there is two rows for addition ..

for third window (4-3) .. there are 5 rows

clear all
clc

X = readmatrix('NEW.csv');  % data is also attached here 

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/movsum.html#namevaluepairarguments

movsum() with 'Endpoints', 'shrink'