Calculating the percent true and using it in a job

datafeed_config.json

{
      "indices" : [
        "kibana_sample_data_flights"
      ],
      "query" : {
        "bool" : {
          "must" : [
            {
              "match_all" : { }
            }
          ]
        }
      },
      "aggregations" : {
        "buckets" : {
          "date_histogram" : {
            "field" : "timestamp",
            "fixed_interval" : "15m"
          },
          "aggs" : {
            "timestamp" : {
              "max" : {
                "field" : "timestamp"
              }
            },
            "num_true" : {
              "sum" : {
                "field" : "Cancelled"
              }
            },
            "total" : {
              "value_count" : {
                "field" : "timestamp"
              }
            },
            "percent_true" : {
              "bucket_script" : {
                "buckets_path" : {
                  "num_true" : "num_true",
                  "total" : "total"
                },
                "script" : {
                  "source" : "params.num_true/params.total"
                }
              }
            }
          }
        }
      }
    }

job_config.json

{
      "description" : "",
      "analysis_config" : {
        "bucket_span" : "15m",
        "summary_count_field_name" : "doc_count",
        "detectors" : [
          {
            "detector_description" : "mean(percent_true)",
            "function" : "mean",
            "field_name" : "percent_true",
            "detector_index" : 0
          }
        ],
        "influencers" : [ ]
      },
      "analysis_limits" : {
        "model_memory_limit" : "11mb",
        "categorization_examples_limit" : 4
      },
      "data_description" : {
        "time_field" : "timestamp",
        "time_format" : "epoch_ms"
      },
      "model_plot_config" : {
        "enabled" : true,
        "annotations_enabled" : false
      }
    }