LocalMax

The LocalMax metafeature detects when a signal has a local maximum; i.e. a point in time when just prior and just after that point the signal is less. It should not be confused with the global maximum and minimum functions that operate on the whole channel. It produces instantiated feature tuples consisting of the following parameters:

• time: This is as for the midTime parameter for the Increasing metafeature.
• value: The height of the maximum. If useRelativeHeight is used, then the height above the mean for the channel is given.

It operates on a single channel. It accepts the following settings:

• channel: This is as for Increasing.

• useRelativeTime: This is as for Increasing.

• useRelativeHeight: This is as for Increasing.

• windowSize: This controls the minimum ``width'' of the maximum. It is an odd positive integer. A value of 3, for instance, on a channel $c$ would mean that $c[t-1] < c[t] > c[t+1]$. A value of 5 would mean that $c[t-2] < c[t-1] < c[t] > c[t+1] > c[t+2]$. In general, if the window size is $w$ then this means that for a point to be considered a maximum $c[t-\lfloor \frac{w}{2} \rfloor] < ... < c[t-1] < c[t] > c[t+1] > ... > c[t+\lfloor \frac{w}{2} \rfloor]$. The default value is 3 (i.e., the values immediately to the left and right must be less than the current value).