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我有一个数据集，每天为每个 mac 地址填充 0 到 48 个测量值（每半小时一次）（有时由于各种原因我们可能无法获得每个测量值）。通常，我按天分组并取测量值的平均值，但是随着 MAC 地址数量的增加，我们打算用更少的测量值来构成平均值。这是我执行的查询示例：

select fmc.mac_address, 
           inf.node, 
           inf.uf, 
           inf.cidade,
           date_trunc('day', fmc.data) as data,
           avg(inf.qoe) as qoe, 
           avg(inf.qoe_download) as qoe_download,
           avg(inf.qoe_upload) as qoe_upload, 
           avg(inf.qoe_packetloss) as qoe_packetloss,
           avg(inf.qoe_latency) as qoe_latency, 
           avg(inf.qoe_jitter) as qoe_jitter
    
    from fixa_medicoes_claro fmc inner join public.inference_mac inf on fmc.mac_address = inf.mac
    
    where data >= '2020-12-14'
    and mac_address in {}
    
    group by fmc.mac_address, 
             inf.node, 
             inf.uf, 
             inf.cidade,
             date_trunc('day', fmc.data)

现在我们想为每个分组数据查询较少数量的样本，但有一个限制，无论 mac_address 每天的测量次数是多少，我想查询其中的最大“n”个样本，同时也限制它们是时间间隔相等。Ps.：时间戳只记录一天，所以我们不知道特定样本的小时/分钟。

CMake 在 Windows 上找不到 Boost

我有一个非常简单的 CMake 文件，它在 linux 上运行良好，但在 Windows 上，它说它找不到 boost（即使它似乎找到它，因为它说“找到合适的版本”）。这是初始构建文件：

cmake_minimum_required(VERSION 3.16.3)
project(filecompare)

set(CMAKE_CXX_STANDARD 20)

find_package(Boost 1.73.0 COMPONENTS program_options)

if(Boost_FOUND)
    include_directories(${Boost_INCLUDE_DIRS})
    add_executable(filecompare filecompare.cpp)
    target_link_libraries(filecompare ${Boost_LIBRARIES})
endif()

CMake 输出：

-- Could NOT find Boost (missing: Boost_INCLUDE_DIR program_options) (Required is at least version "1.73.0")
-- Configuring done
-- Generating done
-- Build files have been written to: C:/repos/filecompare/cmake-build-debug

所以它似乎无法自己找到库，所以我在 find_package 上面添加了这些行：

SET(CMAKE_INCLUDE_PATH ${CMAKE_INCLUDE_PATH} "C:/local/boost_1_73_0")
SET(CMAKE_LIBRARY_PATH ${CMAKE_LIBRARY_PATH} "C:/local/boost_1_73_0/lib64-msvc-14.2")

现在它似乎以某种方式找到了库，但没有，这是输出：

-- Could NOT find Boost (missing: program_options) (found suitable version "1.73.0", minimum required is "1.73.0")
-- Configuring done
-- Generating done
-- Build files have been written to: C:/repos/filecompare/cmake-build-debug

我尝试设置如下内容：

set(Boost_USE_STATIC_LIBS ON)
set(Boost_USE_MULTITHREADED ON)
set(Boost_USE_STATIC_RUNTIME OFF)
SET(BOOST_ROOT "C:/local/boost_1_73_0/boost")

但这也无济于事。那么我在这里做错了什么？我在带有 VisualStudio 2019 的 CLion 上使用 clang-cl

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1 回答 1

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您可以使用row_number()获取随机样本：

select . . .
from (select fmc.*, inf.*, -- the columns you need
             row_number() over (partition by mac_address order by random()) as seqnum
      from fixa_medicoes_claro fmc inner join
           public.inference_mac inf
           on fmc.mac_address = inf.mac    
      where data >= '2020-12-14' and
            mac_address in {}
     ) fi
where seqnum <= 10
group by . . .

如果您希望行均匀分布，那么一个简单的方法是ntile()使用row_number()：

select . . .
from (select fi.*,
             row_number() over (partition by mac_address, tile order by fmc_data) as seqnum
      from (select fmc.*, inf.*, -- the columns you need
                   ntile(10) over (partition by mac_address order by fmc_data) as tile
            from fixa_medicoes_claro fmc inner join
                 public.inference_mac inf
                 on fmc.mac_address = inf.mac    
            where data >= '2020-12-14' and
                  mac_address in {}
           ) fi
     ) fi
where seqnum <= 1
group by . . .
于 2020-12-18T13:15:26.160 回答