Julia 中有 Counter 对象吗？

Question

在 Python 中，可以使用高性能对象对列表中的项目进行计数 collections.Counter:

>>> from collections import Counter
>>> l = [1,1,2,4,1,5,12,1,51,2,5]
>>> Counter(l)
Counter({1: 4, 2: 2, 5: 2, 4: 1, 12: 1, 51: 1})

我在 http://docs.julialang.org/en/latest/search.html?q=counter 中搜索过，但似乎找不到计数器对象。

我也看过http://docs.julialang.org/en/latest/stdlib/collections.html，但我也没找到。

我试过 Julia 中的直方图函数，它返回了一波弃用消息：

> l = [1,1,2,4,1,5,12,1,51,2,5]
> hist(l)

[输出]:

WARNING: sturges(n) is deprecated, use StatsBase.sturges(n) instead.
 in depwarn(::String, ::Symbol) at ./deprecated.jl:64
 in sturges(::Int64) at ./deprecated.jl:623
 in hist(::Array{Int64,1}) at ./deprecated.jl:646
 in include_string(::String, ::String) at ./loading.jl:441
 in execute_request(::ZMQ.Socket, ::IJulia.Msg) at /Users/liling.tan/.julia/v0.5/IJulia/src/execute_request.jl:175
 in eventloop(::ZMQ.Socket) at /Users/liling.tan/.julia/v0.5/IJulia/src/eventloop.jl:8
 in (::IJulia.##13#19)() at ./task.jl:360
while loading In[65], in expression starting on line 1
WARNING: histrange(...) is deprecated, use StatsBase.histrange(...) instead
 in depwarn(::String, ::Symbol) at ./deprecated.jl:64
 in histrange(::Array{Int64,1}, ::Int64) at ./deprecated.jl:582
 in hist(::Array{Int64,1}, ::Int64) at ./deprecated.jl:645
 in hist(::Array{Int64,1}) at ./deprecated.jl:646
 in include_string(::String, ::String) at ./loading.jl:441
 in execute_request(::ZMQ.Socket, ::IJulia.Msg) at /Users/liling.tan/.julia/v0.5/IJulia/src/execute_request.jl:175
 in eventloop(::ZMQ.Socket) at /Users/liling.tan/.julia/v0.5/IJulia/src/eventloop.jl:8
 in (::IJulia.##13#19)() at ./task.jl:360
while loading In[65], in expression starting on line 1
WARNING: hist(...) and hist!(...) are deprecated. Use fit(Histogram,...) in StatsBase.jl instead.
 in depwarn(::String, ::Symbol) at ./deprecated.jl:64
 in #hist!#994(::Bool, ::Function, ::Array{Int64,1}, ::Array{Int64,1}, ::FloatRange{Float64}) at ./deprecated.jl:629
 in hist(::Array{Int64,1}, ::FloatRange{Float64}) at ./deprecated.jl:644
 in hist(::Array{Int64,1}, ::Int64) at ./deprecated.jl:645
 in hist(::Array{Int64,1}) at ./deprecated.jl:646
 in include_string(::String, ::String) at ./loading.jl:441
 in execute_request(::ZMQ.Socket, ::IJulia.Msg) at /Users/liling.tan/.julia/v0.5/IJulia/src/execute_request.jl:175
 in eventloop(::ZMQ.Socket) at /Users/liling.tan/.julia/v0.5/IJulia/src/eventloop.jl:8
 in (::IJulia.##13#19)() at ./task.jl:360
while loading In[65], in expression starting on line 1

**Is there a Counter object in Julia?**

Answer 1

如果您使用的是 Julia 0.5+，则直方图函数 has been deprecated 并且您应该改用 StatsBase.jl 模块。警告中也有描述：

WARNING: hist(...) and hist!(...) are deprecated. Use fit(Histogram,...) in StatsBase.jl instead.

但如果您使用的是 StatsBase.jl，可能 countmap 更接近您的需要：

julia> import StatsBase: countmap                                                                                                                                             

julia> countmap([1,1,2,4,1,5,12,1,51,2,5])                                                                                                                                    
Dict{Int64,Int64} with 6 entries:
  4  => 1
  2  => 2
  5  => 2
  51 => 1
  12 => 1
  1  => 4

Answer 2

DataStructures.jl package also has Accumulators / Counters同一个使用和组合计数器的通用方法集。

添加包后

using Pkg
Pkg.add("DataStructures")

你可以通过构造一个计数器来对一个序列的元素进行计数

# generate some data to count
using Random

seq = [ Random.randstring('a':'c', 2) for _ in 1:100 ]


# count the elements in seq
using DataStructures

counts = counter(seq)

Julia 中有 Counter 对象吗？

Is there a Counter object in Julia?

containers

counter

histogram

julia