我想获取以下数组的绝对值:
x = [1.1 -22.3 3.01, -1]
即:我想要一个类型的输出:x2 = [1.1 22.3 3.01 1]
但是当我输入:
abs(x)
我收到一个错误:
ERROR: MethodError: no method matching abs(::Array{Float64,2})
Closest candidates are:
abs(::Pkg.Resolve.MaxSum.FieldValues.FieldValue) at /Users/vagrant/worker/juliapro-release-osx1011-0_6/build/tmp_julia/Julia-1.0.app/Contents/Resources/julia/share/julia/stdlib/v1.0/Pkg/src/resolve/FieldValues.jl:67
abs(::Pkg.Resolve.VersionWeights.VersionWeight) at /Users/vagrant/worker/juliapro-release-osx1011-0_6/build/tmp_julia/Julia-1.0.app/Contents/Resources/julia/share/julia/stdlib/v1.0/Pkg/src/resolve/VersionWeights.jl:40
abs(::Missing) at missing.jl:79
...
Stacktrace:
[1] top-level scope at none:0
Julia 不会自动将标量函数(如 abs
)应用于数组的元素。相反,您应该告诉 Julia 这是您想要的,并在数组上广播标量函数abs
,请参阅 https://docs.julialang.org/en/v1/manual/arrays/#Broadcasting-1。这可以作为
julia> x = [1.1, -22.3, 3.01, -1];
julia> broadcast(abs, x)
4-element Array{Float64,1}:
1.1
22.3
3.01
1.0
或者你可以使用"点符号",它更意识形态:
julia> abs.(x)
4-element Array{Float64,1}:
1.1
22.3
3.01
1.0