朱莉娅边缘的条件总和

Question

我有一个复杂的问题,我必须从先前构建的图形中评估边缘的总和.朱莉娅似乎没有处理带边的条件和.

这是一个类似于我想要解决的问题的简单问题:

module EssaiModule

using LightGraphs, MetaGraphs

g = DiGraph(6)
mg = MetaDiGraph(g, 1.0)
add_vertex!(mg)
add_edge!(mg,1,2)
add_edge!(mg,1,3)
add_edge!(mg,1,4)
add_edge!(mg,2,4)
add_edge!(mg,2,5)
add_edge!(mg,3,5)
add_edge!(mg,5,6)
add_edge!(mg,4,6)

set_props!(mg,3,Dict(:port=>1,:vessel=>2))
set_props!(mg,1,Dict(:port=>1,:vessel=>0))
set_props!(mg,2,Dict(:port=>1,:vessel=>0))
set_props!(mg,4,Dict(:port=>1,:vessel=>2))
set_props!(mg,5,Dict(:port=>0,:vessel=>2))
set_props!(mg,6,Dict(:port=>0,:vessel=>0))

SI = sum(1 for e in edges(mg);get_prop(g,dst(e),:vessel)==2 && get_prop(g,dst(e),:port)==1)

println(SI)

end

当我测试它时,我得到了错误

#LoadError: MethodError: no method matching dst(::Irrational{:e})

我真的需要弄清楚如何与条件求和,因为在我的实际问题中,我将这个和放在一个约束中,就像这样,边ed和和x变量之和:

@constraint(model, cM[e in edges(g)], x[e] + sum(x[ed] for ed in edges(g) ; fn1(ed) == 2 && fn2(ed) == 1) <= 1 + y)

我有错误信息说

#LoadError: UndefVarError: ed not defined

所以我的问题如下:

1. 为什么第一个代码不起作用,因为类型e是Int？

2. 我是以不好的方式写约束的吗？

对不起我无法上传真正的问题,内容和数据都不会上线,加上它太大了.

Answer 1

对于问题的第一部分,您需要更改函数调用

SI = sum(1 for e in edges(mg);get_prop(g,dst(e),:vessel)==2 && get_prop(g,dst(e),:port)==1)
#                            ^ you end the statement with a semicolon
# after the semicolon, keyword arguments of a function, in this case `sum`,
# begins. then, the compiler checks the function `dst` and cannot find a proper
# method that is implemented for e, that is, the irrational number e.

如下:

SI = length([e for e in edges(mg) if get_prop(mg, dst(e), :vessel) == 2 &&
                                     get_prop(mg, dst(e), :port  ) == 1   ])

println(SI) # prints 3

另请注意代码中的拼写错误.get_prop 需要检查mg,而不是g.您还应该查看文档的" 理解"部分.

对于问题的第二部分,您应该为我们提供宏定义,以便更好地帮助您.很可能,您没有在宏内插入表达式/变量.请参阅我对其他问题的回答,并告诉我这是否有帮助.

编辑1.实际上,你的第二部分也有同样的问题.在里面sum,你用分号结束位置参数并启动关键字参数.

编辑2.根据下面DNF的评论,您甚至应该使用count更具表现力(源代码)和高效版本:

SI = count(e->(get_prop(mg, dst(e), :vessel) == 2 &&
               get_prop(mg, dst(e), :port  ) == 1   ), edges(mg))
# or,
SI = count(get_prop(mg, dst(e), :vessel) == 2 &&
           get_prop(mg, dst(e), :port  ) == 1    for e in edges(mg))

编辑3.表现比较如下:

Pkg.add("BenchmarkTools")
using BenchmarkTools

@benchmark count(e->(get_prop(mg, dst(e), :vessel) == 2 &&
                     get_prop(mg, dst(e), :port  ) == 1   ), edges(mg))

BenchmarkTools.Trial:
  memory estimate:  7.73 KiB
  allocs estimate:  53
  --------------
  minimum time:     2.201 ?s (0.00% GC)
  median time:      2.494 ?s (0.00% GC)
  mean time:        3.191 ?s (15.69% GC)
  maximum time:     198.515 ?s (95.69% GC)
  --------------
  samples:          10000
  evals/sample:     9

@benchmark count(get_prop(mg, dst(e), :vessel) == 2 &&
                 get_prop(mg, dst(e), :port  ) == 1    for e in edges(mg))

BenchmarkTools.Trial:
  memory estimate:  7.75 KiB
  allocs estimate:  54
  --------------
  minimum time:     2.352 ?s (0.00% GC)
  median time:      2.661 ?s (0.00% GC)
  mean time:        3.712 ?s (15.10% GC)
  maximum time:     236.440 ?s (95.06% GC)
  --------------
  samples:          10000
  evals/sample:     9

@benchmark length([e for e in edges(mg) if get_prop(mg, dst(e), :vessel) == 2 &&
                                           get_prop(mg, dst(e), :port  ) == 1])

BenchmarkTools.Trial:
  memory estimate:  8.13 KiB
  allocs estimate:  60
  --------------
  minimum time:     2.642 ?s (0.00% GC)
  median time:      2.789 ?s (0.00% GC)
  mean time:        3.553 ?s (14.54% GC)
  maximum time:     231.424 ?s (94.73% GC)
  --------------
  samples:          10000
  evals/sample:     9

count版本的效率似乎比10%高length,这可能会对您实际的更大问题产生影响.

编辑4.由于DNF,再次进行基准测试的正确方法如下:

@benchmark count(e->(get_prop($mg, dst(e), :vessel) == 2 &&
                     get_prop($mg, dst(e), :port  ) == 1   ), edges($mg))

BenchmarkTools.Trial:
  memory estimate:  7.72 KiB
  allocs estimate:  52
  --------------
  minimum time:     2.320 ?s (0.00% GC)
  median time:      2.478 ?s (0.00% GC)
  mean time:        2.952 ?s (10.33% GC)
  maximum time:     117.306 ?s (93.38% GC)
  --------------
  samples:          10000
  evals/sample:     9

@benchmark count(get_prop($mg, dst(e), :vessel) == 2 &&
                 get_prop($mg, dst(e), :port  ) == 1    for e in edges($mg))

BenchmarkTools.Trial:
  memory estimate:  7.73 KiB
  allocs estimate:  53
  --------------
  minimum time:     2.340 ?s (0.00% GC)
  median time:      2.524 ?s (0.00% GC)
  mean time:        3.030 ?s (11.17% GC)
  maximum time:     197.018 ?s (94.35% GC)
  --------------
  samples:          10000
  evals/sample:     9