MathExpression¶

class aws_cdk.aws_cloudwatch.MathExpression(*, expression, using_metrics, color=None, label=None, period=None)¶

Bases: object

A math expression built with metric(s) emitted by a service.

The math expression is a combination of an expression (x+y) and metrics to apply expression on. It also contains metadata which is used only in graphs, such as color and label. It makes sense to embed this in here, so that compound constructs can attach that metadata to metrics they expose.

This class does not represent a resource, so hence is not a construct. Instead, MathExpression is an abstraction that makes it easy to specify metrics for use in both alarms and graphs.

Parameters

expression (str) – The expression defining the metric.
using_metrics (Mapping[str, IMetric]) – The metrics used in the expression, in a map. The key is the identifier that represents the given metric in the expression, and the value is the actual Metric object.
color (Optional[str]) – Color for this metric when added to a Graph in a Dashboard. Default: - Automatic color
label (Optional[str]) – Label for this metric when added to a Graph in a Dashboard. Default: - Expression value is used as label
period (Optional[Duration]) – The period over which the expression’s statistics are applied. This period overrides all periods in the metrics used in this math expression. Default: Duration.minutes(5)

Methods

create_alarm(scope, id, *, evaluation_periods, threshold, actions_enabled=None, alarm_description=None, alarm_name=None, comparison_operator=None, datapoints_to_alarm=None, evaluate_low_sample_count_percentile=None, period=None, statistic=None, treat_missing_data=None)¶

Make a new Alarm for this metric.

Combines both properties that may adjust the metric (aggregation) as well as alarm properties.

Parameters

scope (Construct) –
id (str) –
evaluation_periods (Union[int, float]) – The number of periods over which data is compared to the specified threshold.
threshold (Union[int, float]) – The value against which the specified statistic is compared.
actions_enabled (Optional[bool]) – Whether the actions for this alarm are enabled. Default: true
alarm_description (Optional[str]) – Description for the alarm. Default: No description
alarm_name (Optional[str]) – Name of the alarm. Default: Automatically generated name
comparison_operator (Optional[ComparisonOperator]) – Comparison to use to check if metric is breaching. Default: GreaterThanOrEqualToThreshold
datapoints_to_alarm (Union[int, float, None]) – The number of datapoints that must be breaching to trigger the alarm. This is used only if you are setting an “M out of N” alarm. In that case, this value is the M. For more information, see Evaluating an Alarm in the Amazon CloudWatch User Guide. Default: evaluationPeriods
evaluate_low_sample_count_percentile (Optional[str]) – Specifies whether to evaluate the data and potentially change the alarm state if there are too few data points to be statistically significant. Used only for alarms that are based on percentiles. Default: - Not configured.
period (Optional[Duration]) – (deprecated) The period over which the specified statistic is applied. Cannot be used with MathExpression objects. Default: - The period from the metric
statistic (Optional[str]) – (deprecated) What function to use for aggregating. Can be one of the following: - “Minimum” | “min” - “Maximum” | “max” - “Average” | “avg” - “Sum” | “sum” - “SampleCount | “n” - “pNN.NN” Cannot be used with MathExpression objects. Default: - The statistic from the metric
treat_missing_data (Optional[TreatMissingData]) – Sets how this alarm is to handle missing data points. Default: TreatMissingData.Missing

Return type

Alarm

to_alarm_config()¶

(deprecated) Turn this metric object into an alarm configuration.

Deprecated: use toMetricConfig()
Stability: deprecated
Return type: MetricAlarmConfig

to_graph_config()¶

(deprecated) Turn this metric object into a graph configuration.

Deprecated: use toMetricConfig()
Stability: deprecated
Return type: MetricGraphConfig

to_metric_config()¶

Inspect the details of the metric object.

Return type: MetricConfig

to_string()¶

Returns a string representation of an object.

Return type: str

with_(*, color=None, label=None, period=None)¶

Return a copy of Metric with properties changed.

All properties except namespace and metricName can be changed.

Parameters

color (Optional[str]) – Color for this metric when added to a Graph in a Dashboard. Default: - Automatic color
label (Optional[str]) – Label for this metric when added to a Graph in a Dashboard. Default: - Expression value is used as label
period (Optional[Duration]) – The period over which the expression’s statistics are applied. This period overrides all periods in the metrics used in this math expression. Default: Duration.minutes(5)

Return type

MathExpression

Attributes

color¶

The hex color code, prefixed with ‘#’ (e.g. ‘#00ff00’), to use when this metric is rendered on a graph. The Color class has a set of standard colors that can be used here.

Return type: Optional[str]

expression¶

The expression defining the metric.

Return type: str

label¶

Label for this metric when added to a Graph.

Return type: Optional[str]

period¶

Aggregation period of this metric.

Return type: Duration

using_metrics¶

The metrics used in the expression as KeyValuePair <id, metric>.

Return type: Mapping[str, IMetric]