I have a 2d histogram . I want to set bincontent along one axis in 2D histogram and i will continue work with this modified 2D histogram.

Lets consider i have have a 2D histogram in Delta-eta(x axis) and Delta-phi(yaxis) space. Now i take projection along y axis and scale it with the width binwidth of x axis. Now bincontent of projected histogram at 0 is 24.0126( i have attached root file with this threads). I want to set every bin with this value 24.0126 such that i get flat distribution. I did it . After this modification , i can not get modfied 2D histogram. I want 2D plot after modification along y axis bincontent. Could you please give any comment or suggestion

I modify histProjectionYClone after taking projection along Y axis from hist2D. Now I want to set this modified histProjection in 2D such that if i take projection from this 2D histo along y axis , i get flat distribution.