Replacing valuees in a matrix

Hi

I need to replace values in a vector bg_correction with values from vector Sh_a_po if a condition:

Sh_a_BG <= 0.1*Sh_a_po

is satisfied (for each cell separately)

I have 3 vectors:

%%---

bg_correction =

    0.1120
    0.0495
    0.0261
    0.0158
    0.0393
    0.0096

Sh_a_BG =

    0.0008
    0.0004
    0.0007
    0.1698
    0.1756
    0.0114

Sh_a_po=

    0.0495
    0.0261
    0.0160
    0.0395
    0.0096
    0.0035

   %if Sh_a_BG <= 0.1*Sh_a_po --> replace bg_correction with Sh_a_po

 bg_correction(Sh_a_BG_po<=0.1*Sh_a_po) = Sh_a_po1;

%%

The last line doesn't work

Message at Command Window:

In an assignment A(I) = B, the number of elements in B and I must be the same.

Thanks,

Dominika

Answer 1

[Joseph Cheng]

I would suggest use the find() function. With find you can get the index of values where it is Sh_a_BG_po<=0.1*Sh_a_po.

index = find(Sh_a_BG_po<=0.1*Sh_a_po);
bg_correction(index)=Sh_a_po1(index);

[Joseph Cheng]

additionally your original last line would work but you need to include the (Sh_a_BG_po<=0.1*Sh_a_po) on both sides of the equation.

bg_correction(Sh_a_BG_po<=0.1*Sh_a_po) = Sh_a_po1(Sh_a_BG_po<=0.1*Sh_a_po);

Answer 2

[Dominika]

Thank you!