How to apply a function only to the second column of a matrix
The only way I know of is this. Is there an easier way to apply the sin function to only the second column of a matrix?
julia> m = [1. 2. 3.; 4. 5. 6.; 7. 8. 9. ]
3×3 Array{Float64,2}:
1.0 2.0 3.0
4.0 5.0 6.0
7.0 8.0 9.0
julia> for k = 1:size(m)[1]
m[k,2] = sin(m[k,2])
end
julia> m
3×3 Array{Float64,2}:
1.0 0.909297 3.0
4.0 -0.958924 6.0
7.0 0.989358 9.0
How about @views m[:,2] .= sin.(m[:, 2]). This will also work without the @views but then will be making a copy with m[:, 2].
julia> m = [1. 2. 3.; 4. 5. 6.; 7. 8. 9. ]
3×3 Array{Float64,2}:
1.0 2.0 3.0
4.0 5.0 6.0
7.0 8.0 9.0
julia> @views m[:,2] .= sin.(m[:, 2])
3-element view(::Array{Float64,2}, :, 2) with eltype Float64:
0.9092974268256817
-0.9589242746631385
0.9893582466233818
julia> m
3×3 Array{Float64,2}:
1.0 0.909297 3.0
4.0 -0.958924 6.0
7.0 0.989358 9.0