rolling-count

Input Stack: n: Int TimeSeriesExpr

⇨

Output Stack: TimeSeriesExpr

Number of occurrences within a specified window. This operation is frequently used in alerting expressions to reduce noise. For example:

# Check to see if average cpu usage is > 80%
name,cpuUser,:eq,:avg,80,:gt,

# Only alert if that is true for more than 3 of the last 5
# datapoints
5,:rolling-count,3,:gt

A value is counted if it is non-zero. Missing values, NaN, will be treated as zeroes. For example:

Input	3,:rolling-count
0	0
1	1
-1	2
NaN	2
0	1
1	1
1	2
1	3
1	3
0	2

The window size, n, is the number of datapoints to consider including the current value. Note that it is based on datapoints not a specific amount of time. As a result the number of occurrences will be reduced when transitioning to a larger time frame that causes consolidation.

Before	After
:random, 0.4,:gt	:random, 0.4,:gt, 5,:rolling-count