删除 julia 数组中的元素 [英] Delete element in an array for julia

问题描述

我在文档和论坛中徘徊了一段时间，但我还没有找到一个内置的方法/函数来完成删除数组中元素的简单任务.有这样的内置功能吗?

I've been wandering for a while in the docs and in forums and I haven't found a built in method/function to do the simple task of deleting an element in an array. Is there such built-in function?

我要求相当于 python 的 list.remove(x).

I am asking for the equivalent of python's list.remove(x).

这是一个天真地从框中挑选函数的示例:

Here's an example of naively picking a function from the box:

julia> a=Any["D","A","s","t"]
julia> pop!(a, "s")
ERROR: MethodError: `pop!` has no method matching       
pop!(::Array{Any,1},     ::ASCIIString)
Closest candidates are:
  pop!(::Array{T,1})
  pop!(::ObjectIdDict, ::ANY, ::ANY)
  pop!(::ObjectIdDict, ::ANY)
  ...

这里提到使用deleteat!，但也不起作用:

Here mentions to use deleteat!, but also doesn't work:

julia> deleteat!(a, "s")
ERROR: MethodError: `-` has no method matching -(::Int64, ::Char)
Closest candidates are:
  -(::Int64)
  -(::Int64, ::Int64)
  -(::Real, ::Complex{T<:Real})
  ...

 in deleteat! at array.jl:621

推荐答案

你也可以用 filter!:

a = Any["D", "A", "s", "t"]
filter!(e->e≠"s",a)
println(a)

给予:

Any["D","A","t"]

这允许一次删除多个值，如:

This allows to delete several values at once, as in:

filter!(e->e∉["s","A"],a)

注意 1:在 Julia 0.5 中，匿名函数要快得多，并且在 0.4 中感受到的小惩罚不再是问题 :-).

Note 1: In Julia 0.5, anonymous functions are much faster and the little penalty felt in 0.4 is not an issue anymore :-) .

注意 2:上面的代码使用 unicode 运算符.使用普通运算符:≠ 是 != 并且 e∉[a,b] 是 !(e in [a,b])

Note 2: Code above uses unicode operators. With normal operators: ≠ is != and e∉[a,b] is !(e in [a,b])

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