reading file and writing in matrix

I have got a data file with number density at corresponding radius inside. Part of the code is shown below: (the first column is the number density, the second column is the radial distance from the origin.)

    0.000000	38.817338
    0.000802	38.990518
    0.000000	39.163698
    0.000788	39.336878
    0.000782	39.510058
    0.000000	39.683238
    0.000000	39.856419
    0.000761	40.029599
    0.000000	40.202779

There are many other zeros and non-zeros data. And I want to make it to be the initial condition of some function u which satisfies the diffusion equation in cartesian coordinate. For the part of diffusion equation, I have set a set of for loop to initialize u.

    u=zeros(m,m,m,r);
    for l=1:r
        for k=1:m
            for j=1:m
                for i=1:m
                    if (i==1) && (j==1) && (k==1)
                        u(i,j,k,l)=(u1+u4+u5)/3;
                    ...
                    elseif (k==m)
                        u(i,j,k,l)=u2;
                    else
                        u(i,j,k,l)=u7
                    end
                end
            end
        end
    end

where l ranging from 1 to r indicates the time coordinate, u7 is the original constant value initial condition applied to the whole system.

My problem is how could I fit the set of number density data in the initial condition.