Counter Blocks

This repository comprises several different types of counters.

• Counter
• CounterFast
• NumericCounter

Counter

Counts the number of signals that pass through the block. It outputs the count for each list of signals that is processed by the block and a cumluative_count which is the total number signals that have been processed by the block since the last rest.

Signals can optionally be grouped using the group_by property. This is an evaluable expression that will group the counts and specify the group in the group attribute on the output signal.

Persistance is used to maintain the cumulative count between stopping and starting the block.

The cumulative count can be reset by using the reset command or by using one of the reset_info options. The reset_info properties allow for configuration of the block to reset the cumulative count based on a recurring INTERVAL or a specific time by using the CRON setting. On reset, a signal is notified. It contains the cumulative_count right before the reset and the count is zero.

Properties

• reset_info: If resetting is true, cumulative_count will reset at a specified interval or time. When scheme is set to INTERVAL then cumulative_count will reset every interval. When scheme is set to CRON then cumulative_count will reset at every at (in UTC time).
• group_by: Expression proprety. The value by which signals are grouped. Output signals will have group set to this value.

Dependencies

GroupBy Block Supplement

Commands

• reset: Notifes a signal with count equal to 0 and cumulative_count equal to the cumulative count. Cumulative count is then set to 0.

Input

Any list of signals.

Output

• count: Number of signals that were sent into the signal.
• cumulative_count: Number of signals since reset.
• group: The group that the counts relate to as defined by group_by.

CounterFast

A faster counter that ignores groups and provides functionality to return signal frequency over a configured period. There is no interaction with Persistence.

The cumulative count can be reset by the reset command.

Properties

• frequency:
  • enabled (bool): Is frequency reporting enabled?
  • report_interval (timedelta): The interval at which to report frequencies.
  • averaging_interval (timedelta): The interval over which to calculate frequencies.

Dependencies

None

Commands

• reset: Cumulative count is then set to 0. Returns True.
• value: Returns the cumulative count.

Input

Any list of signals.

Output

• count: Number of signals processed.
• cumulative_count: Number of signals since last reset.

NumericCounter

The same as the Counter Block but it expects count values to be passed to the block rather than lists of signals to be counted.

This is allows for use of the cumulative count and reset functionality of the counter block, but does not require large numbers of signals to be passed if count data is already available.

Properties

• count_expr: (expression) The expression to be applied to each signal to extract the count
• reset_info: If resetting is true, cumulative_count will reset at a specified interval or time. When scheme is set to INTERVAL then cumulative_count will reset every interval. When scheme is set to CRON then cumulative_count will reset at every at (in UTC time).
• group_by: Expression proprety. The value by which signals are grouped. Output signals will have group set to this value.

Dependencies

GroupBy Block Supplement

Commands

• reset: Notifes a signal with count equal to 0 and cumulative_count equal to the cumulative count. Cumulative count is then set to 0.

Input

Any list of signals.

Output

• count: Number of signals that were sent into the signal.
• cumulative_count: Number of signals since reset.
• group: The group that the counts relate to as defined by group_by.