Computes various measures that can indicate the presence and structures of
intermittent data.

## Arguments

- x
A vector to extract features from.

## Value

A vector of named features:

zero_run_mean: The average interval between non-zero observations

nonzero_squared_cv: The squared coefficient of variation of non-zero observations

zero_start_prop: The proportion of data which starts with zero

zero_end_prop: The proportion of data which ends with zero

## References

Kostenko, A. V., & Hyndman, R. J. (2006). A note on the categorization of
demand patterns. *Journal of the Operational Research Society*, 57(10),
1256-1257.