# Catch22.jl

A Julia package wrapping *catch22*, which is a set of 22 time-series features shown by Lubba et al. (2019) to be performant in a range of time-series classification problems.

The *catch22* repository provides these 22 features, originally coded in Matlab as part of the *hctsa* toolbox, as C functions (in addition to Matlab and Python wrappers). This package simply uses Julia's `ccall`

to wrap these C functions from a shared library that is accessed through catch22_jll and compiled by the fantastic BinaryBuilder package.

# Usage

## Installation

```
using Pkg
Pkg.add("Catch22")
using Catch22
```

## Input time series

The input time series can be provided as a `Vector{Float64}`

or `Array{Float64, 2}`

. If an array is provided, the time series must occupy its *columns*. For example, this package contains a few test time series from *catch22*:

```
๐ฑ = Catch22.testdata[:testSinusoid] # a Vector{Float64}
X = randn(1000, 10) # an Array{Float64, 2} with 10 time series
```

## Evaluating a feature

A list of features (as symbols) can be obtained with `getnames(catch22)`

and their short descriptions with `getdescriptions(catch22)`

. Each feature can be evaluated for a time series array or vector with the `catch22`

`FeatureSet`

. For example, the feature `DN_HistogramMode_5`

can be evaluated using:

```
f = catch22[:DN_HistogramMode_5](๐ฑ) # Returns a scalar Float64
๐ = catch22[1](X) # Returns a 1ร10 Matrix{Float64}
```

All features are returned as Float64's, even though some may be constrained to the integers.

Alternatively, functions that calculate each feature individually are exported. `DN_HistogramMode_5`

can be evaluated with:

`f = DN_HistogramMode_5(๐ฑ)`

## Evaluating a feature set

All *catch22* features can be evaluated with:

```
๐ = catch22(๐ฑ)
F = catch22(X)
```

If an array is provided, containing one time series in each of N columns, then a 22รN `FeatureArray`

of feature values will be returned (a subtype of AbstractDimArray).
A `FeatureArray`

has most of the properties and methods of an Array but is annotated with feature names that can be accessed with `getnames(F)`

.
If a vector is provided (a single time series) then a vector of feature values will be returned as a `FeatureVector`

, a one-dimensional `FeatureArray`

.

Finally, note that since `catch22`

is a `FeatureSet`

it can be indexed with a vector of feature names as symbols to calculate a `FeatureArray`

for a subset of *catch22*. For details on the `Feature`

, `FeatureSet`

and `FeatureArray`

types check out the package docs.

# Single-threaded performance

Calculating features for a single time series of a given length: