Class inertialsim::sensors::Measurement¶

ClassList > inertialsim > sensors > Measurement

#include <measurement.h>

Public Functions¶

Type	Name
Measurement	Slice (int start, int end) const Return a slice of the measurement samples.
const Array &	data () const Return the measurement data array.
Array &	data ()
int	num_channels () const The number of independent channels or axes of measurement.
int	num_measurements () const The number of measurement samples.
Measurement	operator[] (int index) const Return an indexed element of the current instance.
double	sample_rate () const Return the measurement sample rate in Hz.
const Timestamps &	time () const Return the measurement timestamps.
Timestamps &	time ()

Public Static Functions¶

Type	Name
Measurement	FromMeasurements (const std::vector< Measurement > & measurements) Construct a Measurement from a collection of Measurements.
Measurement	FromSampledData (const Array & data, double sample_rate) Construct a Measurement from uniformly sampled data.
Measurement	FromTimestampedData (const Array & data, const Timestamps & time, std::optional< double > sample_rate=std::nullopt) Construct a Measurement from timestamped data.

Detailed Description¶

Time-sampled sensor measurement data. Measurement data can be timestamped with a time of validity for each measurement datum or can be uniformly sampled at a fixed rate. Measurements can consist of any number of channels (e.g., 3-axis sensors have 3 channels).

Use the static From* methods to construct an instance.

** **

Data is organized with samples in rows and channels in columns: * Shape (N,): Single channel, N samples * Shape (1, N): Single channel, N samples (equivalent to above) * Shape (M, N): M channels, N samples

Example: A 3-axis gyroscope sampled at 100 Hz for 1 second will have shape (3, 100) where the 3 rows represent the x, y, z angular rates.

** **

For timestamped data, sample rate consistency is important for many algorithms. The class validates that timestamps are consistent with the expected sample rate.

Public Functions Documentation¶

function Slice¶

Return a slice of the measurement samples.

Measurement inertialsim::sensors::Measurement::Slice (
    int start,
    int end
) const

Returns a new Measurement instance containing only the samples in the range [start, end). Both timestamps and data are sliced accordingly.

Parameters:

start Starting sample index (inclusive).
end Ending sample index (exclusive).

Returns:

New Measurement instance with sliced data and timestamps.

Exception:

std::out_of_range If indices are invalid or inconsistent.

function data [½]¶

Return the measurement data array.

inline const Array & inertialsim::sensors::Measurement::data () const

Returns:

Reference to the data array (channels in rows, samples in columns).

function data [2/2]¶

inline Array & inertialsim::sensors::Measurement::data ()

function num_channels¶

The number of independent channels or axes of measurement.

inline int inertialsim::sensors::Measurement::num_channels () const

function num_measurements¶

The number of measurement samples.

inline int inertialsim::sensors::Measurement::num_measurements () const

function operator[]¶

Return an indexed element of the current instance.

Measurement inertialsim::sensors::Measurement::operator[] (
    int index
) const

Parameters:

index Index of the element to return.

Returns:

New instance containing only the indexed element.

function sample_rate¶

Return the measurement sample rate in Hz.

inline double inertialsim::sensors::Measurement::sample_rate () const

Returns:

The sample rate as a double.

function time [½]¶

Return the measurement timestamps.

inline const Timestamps & inertialsim::sensors::Measurement::time () const

Returns:

Reference to the timestamps array.

function time [2/2]¶

inline Timestamps & inertialsim::sensors::Measurement::time ()

Public Static Functions Documentation¶

function FromMeasurements¶

Construct a Measurement from a collection of Measurements.

static Measurement inertialsim::sensors::Measurement::FromMeasurements (
    const std::vector< Measurement > & measurements
)

Merges a list of Measurement instances into a single instance. Inputs must have a consistent number of channels.

Parameters:

measurements List of Measurement instances to concatenate.

Returns:

A single merged Measurement instance.

function FromSampledData¶

Construct a Measurement from uniformly sampled data.

static Measurement inertialsim::sensors::Measurement::FromSampledData (
    const Array & data,
    double sample_rate
)

A time span is constructed internally using the sample_rate input.

Parameters:

data Array of measurements, with channels in rows and samples in columns.
sample_rate Measurement sample rate (Hz).

Returns:

A Measurement instance.

function FromTimestampedData¶

Construct a Measurement from timestamped data.

static Measurement inertialsim::sensors::Measurement::FromTimestampedData (
    const Array & data,
    const Timestamps & time,
    std::optional< double > sample_rate=std::nullopt
)

Constructs measurement data with explicit timestamps for each sample. Input shape is flexible: * (N,), (1, N): Single channel data * (M, N): Multi-channel data

If sample_rate is provided, the time input is checked for consistency. If sample_rate is null, the median sample rate from the time input is calculated and used. If only one data point is input, sample_rate must be supplied.

Parameters:

data Array of measurements (channels in rows, samples in columns).
time Array of unique, strictly increasing times for each sample.
sample_rate Optional expected sample rate (Hz). If provided, used for validation. If not provided, median is calculated.

Returns:

A Measurement instance.

The documentation for this class was generated from the following file cpp/include/inertialsim/sensors/measurement.h