IBM Watson CPLEX 在求解 LP 文件时显示无变量、无解

Question

我正在将以前运行在 IBM 的 DoCloud 上的应用程序迁移到他们基于 Watson 的新 API。由于我们的应用程序没有 CSV 格式的数据，也没有模型层和数据层之间的分离，因此上传 LP 文件以及读取 LP 文件并求解它的模型文件似乎更简单。我可以上传，它声称可以正确解决，但 returns 空解决状态。我还输出了各种模型信息（例如变量数），所有内容都归零了。我已经确认 LP 不是空白的 - 它有一个微不足道的 MILP。

这是我的模型代码（大部分直接取自https://dataplatform.cloud.ibm.com/exchange/public/entry/view/50fa9246181026cd7ae2a5bc7e4ac7bd的例子）：

import os
import sys
from os.path import splitext

import pandas
from docplex.mp.model_reader import ModelReader
from docplex.util.environment import get_environment
from six import iteritems


def loadModelFiles():
    """Load the input CSVs and extract the model and param data from it
    """
    env = get_environment()
    inputModel = params = None
    modelReader = ModelReader()

    for inputName in [f for f in os.listdir('.') if splitext(f)[1] != '.py']:
        inputBaseName, ext = splitext(inputName)

        print(f'Info: loading {inputName}')

        try:
            if inputBaseName == 'model':
                inputModel = modelReader.read_model(inputName, model_name=inputBaseName)
            elif inputBaseName == 'params':
                params = modelReader.read_prm(inputName)
        except Exception as e:
            with env.get_input_stream(inputName) as inStream:
                inData = inStream.read()
            raise Exception(f'Error: {e} found while processing {inputName} with contents {inData}')

    if inputModel is None or params is None:
        print('Warning: error loading model or params, see earlier messages for details')

    return inputModel, params


def writeOutputs(outputs):
    """Write all dataframes in ``outputs`` as .csv.

    Args:
        outputs: The map of outputs 'outputname' -> 'output df'
    """
    for (name, df) in iteritems(outputs):
        csv_file = '%s.csv' % name
        print(csv_file)
        with get_environment().get_output_stream(csv_file) as fp:
            if sys.version_info[0] < 3:
                fp.write(df.to_csv(index=False, encoding='utf8'))
            else:
                fp.write(df.to_csv(index=False).encode(encoding='utf8'))
    if len(outputs) == 0:
        print("Warning: no outputs written")


# load and solve model
model, modelParams = loadModelFiles()
ok = model.solve(cplex_parameters=modelParams)

solution_df = pandas.DataFrame(columns=['name', 'value'])

for index, dvar in enumerate(model.solution.iter_variables()):
    solution_df.loc[index, 'name'] = dvar.to_string()
    solution_df.loc[index, 'value'] = dvar.solution_value

outputs = {}
outputs['solution'] = solution_df

# Generate output files
writeOutputs(outputs)

try:
    with get_environment().get_output_stream('test.txt') as fp:
        fp.write(f'{model.get_statistics()}'.encode('utf-8'))

except Exception as e:
    with get_environment().get_output_stream('excInfo') as fp:
        fp.write(f'Got exception {e}')

和运行它的代码的存根（再次从示例中大量提取）：

prmFile = NamedTemporaryFile()
prmFile.write(self.ctx.cplex_parameters.export_prm_to_string().encode())
modelFile = NamedTemporaryFile()
modelFile.write(self.solver.export_as_lp_string(hide_user_names=True).encode())
modelMetadata = {
    self.client.repository.ModelMetaNames.NAME: self.name,
    self.client.repository.ModelMetaNames.TYPE: 'do-docplex_12.9',
    self.client.repository.ModelMetaNames.RUNTIME_UID: 'do_12.9'
}
baseDir = os.path.dirname(os.path.realpath(__file__))

def reset(tarinfo):
    tarinfo.uid = tarinfo.gid = 0
    tarinfo.uname = tarinfo.gname = 'root'
    return tarinfo

with NamedTemporaryFile() as tmp:
    tar = tarfile.open(tmp.name, 'w:gz')
    tar.add(f'{baseDir}/ibm_model.py', arcname='main.py', filter=reset)
    tar.add(prmFile.name, arcname='params.prm', filter=reset)
    tar.add(modelFile.name, arcname='model.lp', filter=reset)
    tar.close()

    modelDetails = self.client.repository.store_model(
        model=tmp.name,
        meta_props=modelMetadata
    )

    modelUid = self.client.repository.get_model_uid(modelDetails)

metaProps = {
    self.client.deployments.ConfigurationMetaNames.NAME: self.name,
    self.client.deployments.ConfigurationMetaNames.BATCH: {},
    self.client.deployments.ConfigurationMetaNames.COMPUTE: {'name': 'S', 'nodes': 1}
}
deployDetails = self.client.deployments.create(modelUid, meta_props=metaProps)
deployUid = self.client.deployments.get_uid(deployDetails)

solvePayload = {
    # we upload input data as part of model since only CSV data is supported in this interface
    self.client.deployments.DecisionOptimizationMetaNames.INPUT_DATA: [],
    self.client.deployments.DecisionOptimizationMetaNames.OUTPUT_DATA: [
        {
            "id": ".*"
        }
    ]
}

jobDetails = self.client.deployments.create_job(deployUid, solvePayload)
jobUid = self.client.deployments.get_job_uid(jobDetails)

while jobDetails['entity']['decision_optimization']['status']['state'] not in ['completed', 'failed',
                                                                                'canceled']:
    logger.debug(jobDetails['entity']['decision_optimization']['status']['state'] + '...')
    time.sleep(5)
    jobDetails = self.client.deployments.get_job_details(jobUid)

logger.debug(jobDetails['entity']['decision_optimization']['status']['state'])

# cleanup
self.client.repository.delete(modelUid)
prmFile.close()
modelFile.close()

关于可能导致此问题的原因或什么是好的测试途径有什么想法吗？似乎没有办法查看模型的输出进行调试，我是不是在 Watson studio 中遗漏了什么？

Answer 1

我尝试了与您的代码非常相似的方法，当作业完成时，解决方案包含在有效负载中。

查看此共享笔记本：https://dataplatform.cloud.ibm.com/analytics/notebooks/v2/cfbe34a0-52a8-436c-99bf-8df6979c11da/view?access_token=220636400ecdf537fb5ea1b47d41cb10f1b252199d1814d8f96a0280ec4a4e1e

我是最后一个单元格，作业完成后，我打印状态：

print(jobDetails['entity']['decision_optimization'])

并获得

{'output_data_references': [], 'input_data': [], 'solve_state': {'details': {'PROGRESS_GAP': '0.0', 'MODEL_DETAIL_NONZEROS': '3', 'MODEL_DETAIL_TYPE': 'MILP', 'MODEL_DETAIL_CONTINUOUS_VARS': '0', 'MODEL_DETAIL_CONSTRAINTS': '2', 'PROGRESS_CURRENT_OBJECTIVE': '100.0', 'MODEL_DETAIL_INTEGER_VARS': '2', 'MODEL_DETAIL_KPIS': '[]', 'MODEL_DETAIL_BOOLEAN_VARS': '0', 'PROGRESS_BEST_OBJECTIVE': '100.0'}, 'solve_status': 'optimal_solution'}, 'output_data': [{'id': 'test.txt', 'fields': ['___TEXT___'], 'values': [['IC0gbnVtYmVyIG9mIHZhcmlhYmxlczogMgogICAtIGJpbmFyeT0wLCBpbnRlZ2VyPTIsIGNvbnRpbnVvdXM9MAogLSBudW1iZXIgb2YgY29uc3RyYWludHM6IDIKICAgLSBsaW5lYXI9Mg==']]}, {'id': 'solution.json', 'fields': ['___TEXT___'], 'values': [['eyJDUExFWFNvbHV0aW9uIjogeyJ2ZXJzaW9uIjogIjEuMCIsICJoZWFkZXIiOiB7InByb2JsZW1OYW1lIjogIm1vZGVsIiwgIm9iamVjdGl2ZVZhbHVlIjogIjEwMC4wIiwgInNvbHZlZF9ieSI6ICJjcGxleF9sb2NhbCJ9LCAidmFyaWFibGVzIjogW3siaW5kZXgiOiAiMCIsICJuYW1lIjogIngiLCAidmFsdWUiOiAiNS4wIn0sIHsiaW5kZXgiOiAiMSIsICJuYW1lIjogInkiLCAidmFsdWUiOiAiOTUuMCJ9XSwgImxpbmVhckNvbnN0cmFpbnRzIjogW3sibmFtZSI6ICJjMSIsICJpbmRleCI6IDB9LCB7Im5hbWUiOiAiYzIiLCAiaW5kZXgiOiAxfV19fQ==']]}, {'id': 'solution.csv', 'fields': ['name', 'value'], 'values': [['x', 5], ['y', 95]]}], 'status': {'state': 'completed', 'running_at': '2020-03-09T06:45:29.759Z', 'completed_at': '2020-03-09T06:45:30.470Z'}}

其中包含 output:

'output_data': [{
        'id': 'test.txt',
        'fields': ['___TEXT___'],
        'values': [['IC0gbnVtYmVyIG9mIHZhcmlhYmxlczogMgogICAtIGJpbmFyeT0wLCBpbnRlZ2VyPTIsIGNvbnRpbnVvdXM9MAogLSBudW1iZXIgb2YgY29uc3RyYWludHM6IDIKICAgLSBsaW5lYXI9Mg==']]
    }, {
        'id': 'solution.json',
        'fields': ['___TEXT___'],
        'values': [['eyJDUExFWFNvbHV0aW9uIjogeyJ2ZXJzaW9uIjogIjEuMCIsICJoZWFkZXIiOiB7InByb2JsZW1OYW1lIjogIm1vZGVsIiwgIm9iamVjdGl2ZVZhbHVlIjogIjEwMC4wIiwgInNvbHZlZF9ieSI6ICJjcGxleF9sb2NhbCJ9LCAidmFyaWFibGVzIjogW3siaW5kZXgiOiAiMCIsICJuYW1lIjogIngiLCAidmFsdWUiOiAiNS4wIn0sIHsiaW5kZXgiOiAiMSIsICJuYW1lIjogInkiLCAidmFsdWUiOiAiOTUuMCJ9XSwgImxpbmVhckNvbnN0cmFpbnRzIjogW3sibmFtZSI6ICJjMSIsICJpbmRleCI6IDB9LCB7Im5hbWUiOiAiYzIiLCAiaW5kZXgiOiAxfV19fQ==']]
    }, {
        'id': 'solution.csv',
        'fields': ['name', 'value'],
        'values': [['x', 5], ['y', 95]]
    }
],

希望这对您有所帮助。阿兰

Answer 2

感谢 Alain 验证了整体方法，但主要问题是我的代码中存在一个错误：

调用 modelFile.write(...) 后，有必要调用 modelFile.seek(0) 来重置文件指针 - 否则它会将一个空文件写入 tar 存档

IBM Watson CPLEX 在求解 LP 文件时显示无变量、无解

IBM Watson CPLEX Shows no Variables, no Solution when solving LP file

python

cplex

ibm-cloud

watson-studio

docplex