Package 'rEDM'

Time series for a three-species coupled model.

Description

Time series generated from a discrete-time coupled Lotka-Volterra model exhibiting chaotic dynamics.

Usage

block_3sp

Format

A data frame with 198 rows and 10 columns:

time

time index (# of generations)

x_t

abundance of simulated species x at time t

x_t-1

abundance of simulated species x at time t-1

x_t-2

abundance of simulated species x at time t-2

y_t

abundance of simulated species y at time t

y_t-1

abundance of simulated species y at time t-1

y_t-2

abundance of simulated species y at time t-2

z_t

abundance of simulated species z at time t

z_t-1

abundance of simulated species z at time t-1

z_t-2

abundance of simulated species z at time t-2

---

Convergent cross mapping using simplex projection

Description

The state-space of a multivariate dynamical system (not a purely stochastic one) encodes coherent phase-space variable trajectories. If enough information is available, one can infer the presence or absence of cross-variable interactions associated with causal links between variables. CCM measures the extent to which states of variable Y can reliably estimate states of variable X. This can happen if X is causally influencing Y.

If cross-variable state predictability converges as more state-space information is provided, this indicates a causal link. CCM performs this cross-variable mapping using Simplex, with convergence assessed across a range of observational library sizes as described in Sugihara et al. 2012.

Usage

CCM(pathIn = "./", dataFile = "", dataFrame = NULL,
  E = 0, Tp = 0, knn = 0, tau = -1,
  exclusionRadius = 0, columns = "", target = "", libSizes = "",
  sample = 0, random = TRUE, seed = 0, 
  embedded = FALSE, includeData = FALSE, parameterList = FALSE,
  verbose = FALSE, showPlot = FALSE, noTime = FALSE)

Arguments

pathIn	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values unless noTime is TRUE. The first row must be column names.
dataFrame	input data.frame. The first column must be a time index or time values unless noTime is TRUE. The columns must be named.
E	embedding dimension.
Tp	prediction horizon (number of time column rows).
knn	number of nearest neighbors. If knn=0, knn is set to E+1.
tau	lag of time delay embedding specified as number of time column rows.
exclusionRadius	excludes vectors from the search space of nearest neighbors if their relative time index is within exclusionRadius.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
target	column name used for prediction.
libSizes	string of 3 whitespace separated integer values specifying the intial library size, the final library size, and the library size increment. Can also be a list of strictly increasing library sizes.
sample	integer specifying the number of random samples to draw at each library size evaluation.
random	logical to specify random (TRUE) or sequential library sampling. Note random = FALSE is not convergent cross mapping.
seed	integer specifying the random sampler seed. If seed=0 then a random seed is generated.
embedded	logical specifying if the input data are embedded.
includeData	logical to include statistics and predictions for every prediction in the ensemble.
parameterList	logical to add list of invoked parameters.
verbose	logical to produce additional console reporting.
showPlot	logical to plot results.
noTime	logical to allow input data with no time column.

Details

CCM computes the X:Y and Y:X cross-mappings in parallel using threads.

Value

A data.frame with 3 columns. The first column is LibSize specifying the subsampled library size. Columns 2 and 3 report Pearson correlation coefficients for the prediction of X from Y, and Y from X.

if includeData = TRUE a named list with the following data.frames data.frame Combo_rho columns:

LibMeans	CCM mean correlations for each library size
CCM1_PredictStat	Forward cross map prediction statistics
CCM1_Predictions	Forward cross map prediction values
CCM2_PredictStat	Reverse cross map prediction statistics
CCM2_Predictions	Reverse cross map prediction values

If includeData = TRUE and parameterList = TRUE a named list "parameters" is added.

References

Sugihara G., May R., Ye H., Hsieh C., Deyle E., Fogarty M., Munch S., 2012. Detecting Causality in Complex Ecosystems. Science 338:496-500.

Examples

data(sardine_anchovy_sst)
df = CCM( dataFrame = sardine_anchovy_sst, E = 3, Tp = 0, columns = "anchovy",
target = "np_sst", libSizes = "10 70 10", sample = 100 )

---

2-D timeseries of a circle.

Description

Time series of of circle in 2-D (sin and cos).

Usage

circle

Format

A data frame with 200 rows and 3 columns:

Time

time index.

x

sin component.

y

cos component.

---

Compute error

Description

ComputeError evaluates the Pearson correlation coefficient, mean absolute error and root mean square error between two numeric vectors.

Usage

ComputeError(obs, pred)

Arguments

obs	vector of observations.
pred	vector of predictions.

Value

A name list with components:

rho	Pearson correlation
MAE	mean absolute error
RMSE	root mean square error

Examples

data(block_3sp)
smplx <- Simplex( dataFrame=block_3sp, lib="1 99", pred="105 190", E=3,
columns="x_t", target="x_t")
err <- ComputeError( smplx$Observations, smplx$Predictions )

---

Embed data with time lags

Description

Embed performs Takens time-delay embedding on columns.

Usage

Embed(path = "./", dataFile = "", dataFrame = NULL, E = 0, tau = -1, 
columns = "", verbose = FALSE)

Arguments

path	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values. The first row must be column names. One of dataFile or dataFrame are required.
dataFrame	input data.frame. The first column must be a time index or time values. The columns must be named. One of dataFile or dataFrame are required.
E	embedding dimension.
tau	integer time delay embedding lag specified as number of time column rows.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
verbose	logical to produce additional console reporting.

Details

Each columns item will have E-1 time-lagged vectors created. The column name is appended with (t-n). For example, data columns X, Y, with E = 2 will have columns named X(t-0) X(t-1) Y(t-0) Y(t-1).

The returned data.frame does not have a time column. The returned data.frame is truncated by tau * (E-1) rows to remove state vectors with partial data (NaN elements).

Value

A data.frame with lagged columns. E columns for each variable specified in columns.

Examples

data(circle)
embed <- Embed( dataFrame = circle, E = 2, tau = -1, columns = "x y" )

---

Optimal embedding dimension

Description

EmbedDimension uses Simplex to evaluate prediction accuracy as a function of embedding dimension.

Usage

EmbedDimension(pathIn = "./", dataFile = "", dataFrame = NULL, pathOut = "", 
  predictFile = "", lib = "", pred = "", maxE = 10, Tp = 1, tau = -1,
  exclusionRadius = 0, columns = "", target = "", embedded = FALSE,
  verbose = FALSE, validLib = vector(), numThreads = 4, showPlot = TRUE,
  noTime = FALSE)

Arguments

pathIn	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values unless noTime is TRUE. The first row must be column names.
dataFrame	input data.frame. The first column must be a time index or time values unless noTime is TRUE. The columns must be named.
pathOut	path for predictFile containing output predictions.
predictFile	output file name.
lib	string or vector with start and stop indices of input data rows used to create the library from observations. Mulitple row index pairs can be specified with each pair defining the first and last rows of time series observation segments used to create the library.
pred	string with start and stop indices of input data rows used for predictions. A single contiguous range is supported.
maxE	maximum value of E to evalulate.
Tp	prediction horizon (number of time column rows).
tau	lag of time delay embedding specified as number of time column rows.
exclusionRadius	excludes vectors from the search space of nearest neighbors if their relative time index is within exclusionRadius.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
target	column name used for prediction.
embedded	logical specifying if the input data are embedded.
verbose	logical to produce additional console reporting.
validLib	logical vector the same length as the number of data rows. Any data row represented in this vector as FALSE, will not be included in the library.
numThreads	number of parallel threads for computation.
showPlot	logical to plot results.
noTime	logical to allow input data with no time column.

Value

A data.frame with columns E, rho.

Examples

data(TentMap)
E.rho = EmbedDimension( dataFrame = TentMap, lib = "1 100", pred = "201 500",
columns = "TentMap", target = "TentMap", showPlot = FALSE )

---

Water flow to NE Everglades

Description

Cumulative weekly water flow into northeast Everglades from water control structures S12C, S12D and S333 from 1980 through 2005.

Usage

EvergladesFlow

Format

A data frame with 1379 rows and 2 columns:

Date

Date.

S12CD_S333_CFS

Cumulative weekly flow (CFS).

---

5-D Lorenz'96

Description

5-D Lorenz'96 timeseries with F = 8.

Usage

Lorenz5D

Format

Data frame with 1000 rows and 6 columns

Time

Time.

V1

variable 1.

V2

variable 2.

V3

variable 3.

V4

variable 4.

V5

variable 5.

References

Lorenz, Edward (1996). Predictability - A problem partly solved, Seminar on Predictability, Vol. I, ECMWF.

---

Make embedded data block

Description

MakeBlock performs Takens time-delay embedding on columns. It is an internal function called by Embed that does not perform input error checking or validation.

Usage

MakeBlock(dataFrame, E = 0, tau = -1, columns = "", deletePartial = FALSE)

Arguments

dataFrame	input data.frame. The first column must be a time index or time values. The columns must be named.
E	embedding dimension.
tau	integer time delay embedding lag specified as number of time column rows.
columns	string of whitespace separated column name(s) in the input data to be embedded.
deletePartial	boolean to delete rows with partial data.

Details

Each columns item will have E-1 time-lagged vectors created. The column name is appended with (t-n). For example, data columns X, Y, with E = 2 will have columns named X(t-0) X(t-1) Y(t-0) Y(t-1).

The returned data.frame does not have a time column.

If deletePartial is TRUE, the returned data.frame is truncated by tau * (E-1) rows to remove state vectors with partial data (NaN elements).

Value

A data.frame with lagged columns. E columns for each variable specified in columns.

Examples

data(TentMap)
embed <- MakeBlock(TentMap, 3, 1, "TentMap")

---

Forecasting using multiview embedding

Description

Multiview applies the method of Ye & Sugihara to find optimal combinations of variables that best represent the dynamics.

Usage

Multiview(pathIn = "./", dataFile = "", dataFrame = NULL,
  lib = "", pred = "", D = 0, E = 1, Tp = 1, knn = 0, 
  tau = -1, columns = "", target = "", multiview = 0, exclusionRadius = 0,
  trainLib = TRUE, excludeTarget = FALSE, parameterList = FALSE,
  verbose = FALSE, numThreads = 4, showPlot = FALSE, noTime = FALSE)

Arguments

pathIn	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values. The first row must be column names unless noTime is TRUE.
dataFrame	input data.frame. The first column must be a time index or time values unless noTime is TRUE. The columns must be named.
lib	a 2-column matrix, data.frame, 2-element vector or string of row indice pairs, where each pair specifies the first and last *rows* of the time series to create the library.
pred	(same format as lib), but specifying the sections of the time series to forecast.
D	multivariate dimension.
E	embedding dimension.
Tp	prediction horizon (number of time column rows).
knn	number of nearest neighbors. If knn=0, knn is set to E+1.
tau	lag of time delay embedding specified as number of time column rows.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
target	column name used for prediction.
multiview	number of multiview ensembles to average for the final prediction estimate.
exclusionRadius	number of adjacent observation vector rows to exclude as nearest neighbors in prediction.
trainLib	logical to use in-sample (lib=pred) projections for the ranking of column combinations.
excludeTarget	logical to exclude embedded target column from combinations.
parameterList	logical to add list of invoked parameters.
verbose	logical to produce additional console reporting.
numThreads	number of CPU threads to use in multiview processing.
showPlot	logical to plot results.
noTime	logical to allow input data with no time column.

Details

Multiview embedding is a method to identify variables in a multivariate dynamical system that are most likely to contribute to the observed dynamics. It is a multistep algorithm with these general steps:

1. Compute D-dimensional variable combination forecasts.

2. Rank forecasts.

3. Compute predictions of top combinations.

4. Compute multiview averaged prediction.

If E>1, all variables are embedded to dimension E. If trainLib is TRUE initial forecasts and ranking are done in-sample (lib=pred) and predictions using the top ranked combinations use the specified lib and pred. If trainLib is FALSE initial forecasts and ranking use the specified lib and pred, the step of computing predictions of the top combinations is skipped.

Value

Named list with data.frames [[View, Predictions]].

data.frame View columns:

Col_1	column index
...	column index
Col_D	column index
rho	Pearson correlation
MAE	mean absolute error
RMSE	root mean square error
name_1	column name
...	column name
name_D	column name

If parameterList = TRUE a named list "parameters" is added.

References

Ye H., and G. Sugihara, 2016. Information leverage in interconnected ecosystems: Overcoming the curse of dimensionality. Science 353:922-925.

Examples

data(block_3sp)
L = Multiview( dataFrame = block_3sp, lib = "1 100", pred = "101 190",
E = 2, columns = "x_t y_t z_t", target = "x_t" )

---

Time series for the Paramecium-Didinium laboratory experiment

Description

Time series of Paramecium and Didinium abundances (#/mL) from an experiment by Veilleux (1979)

Usage

paramecium_didinium

---

Forecast interval accuracy

Description

PredictInterval uses Simplex to evaluate prediction accuracy as a function of forecast interval Tp.

Usage

PredictInterval(pathIn = "./", dataFile = "", dataFrame = NULL, pathOut = "./", 
  predictFile = "", lib = "", pred = "", maxTp = 10, E = 1, tau = -1,
  exclusionRadius = 0, columns = "", target = "", embedded = FALSE,
  verbose = FALSE, validLib = vector(), numThreads = 4, showPlot = TRUE,
  noTime = FALSE)

Arguments

pathIn	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values unless noTime is TRUE. The first row must be column names.
dataFrame	input data.frame. The first column must be a time index or time values unless noTime is TRUE. The columns must be named.
pathOut	path for predictFile containing output predictions.
predictFile	output file name.
lib	string or vector with start and stop indices of input data rows used to create the library from observations. Mulitple row index pairs can be specified with each pair defining the first and last rows of time series observation segments used to create the library.
pred	string with start and stop indices of input data rows used for predictions. A single contiguous range is supported.
maxTp	maximum value of Tp to evalulate.
E	embedding dimension.
tau	lag of time delay embedding specified as number of time column rows.
exclusionRadius	excludes vectors from the search space of nearest neighbors if their relative time index is within exclusionRadius.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
target	column name used for prediction.
embedded	logical specifying if the input data are embedded.
verbose	logical to produce additional console reporting.
validLib	logical vector the same length as the number of data rows. Any data row represented in this vector as FALSE, will not be included in the library.
numThreads	number of parallel threads for computation.
showPlot	logical to plot results.
noTime	logical to allow input data with no time column.

Value

A data.frame with columns Tp, rho.

Examples

data(TentMap)
Tp.rho = PredictInterval( dataFrame = TentMap, lib = "1 100",
pred = "201 500", E = 2, columns = "TentMap", target = "TentMap",
showPlot = FALSE )

---

Test for nonlinear dynamics

Description

PredictNonlinear uses SMap to evaluate prediction accuracy as a function of the localisation parameter theta.

Usage

PredictNonlinear(pathIn = "./", dataFile = "", dataFrame = NULL,
  pathOut = "./",  predictFile = "", lib = "", pred = "", theta = "",
  E = 1, Tp = 1, knn = 0, tau = -1, exclusionRadius = 0,
  columns = "", target = "", embedded = FALSE, verbose = FALSE,
  validLib = vector(), ignoreNan = TRUE, numThreads = 4,
  showPlot = TRUE, noTime = FALSE )

Arguments

pathIn	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values unless noTime is TRUE. The first row must be column names.
dataFrame	input data.frame. The first column must be a time index or time values unless noTime is TRUE. The columns must be named.
pathOut	path for predictFile containing output predictions.
predictFile	output file name.
lib	string or vector with start and stop indices of input data rows used to create the library from observations. Mulitple row index pairs can be specified with each pair defining the first and last rows of time series observation segments used to create the library.
pred	string with start and stop indices of input data rows used for predictions. A single contiguous range is supported.
theta	A whitespace delimeted string with values of the S-map localisation parameter. An empty string will use default values of [0.01 0.1 0.3 0.5 0.75 1 1.5 2 3 4 5 6 7 8 9].
E	embedding dimension.
Tp	prediction horizon (number of time column rows).
knn	number of nearest neighbors. If knn=0, knn is set to the library size.
tau	lag of time delay embedding specified as number of time column rows.
exclusionRadius	excludes vectors from the search space of nearest neighbors if their relative time index is within exclusionRadius.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
target	column name used for prediction.
embedded	logical specifying if the input data are embedded.
verbose	logical to produce additional console reporting.
validLib	logical vector the same length as the number of data rows. Any data row represented in this vector as FALSE, will not be included in the library.
ignoreNan	logical to internally redefine library to avoid nan.
numThreads	number of parallel threads for computation.
showPlot	logical to plot results.
noTime	logical to allow input data with no time column.

Details

The localisation parameter theta weights nearest neighbors according to exp( (-theta D / D_avg) ) where D is the distance between the observation vector and neighbor, D_avg the mean distance. If theta = 0, weights are uniformally unity corresponding to a global autoregressive model. As theta increases, neighbors in closer proximity to the observation are considered.

Value

A data.frame with columns Theta, rho.

Examples

data(TentMapNoise)
theta.rho = PredictNonlinear( dataFrame = TentMapNoise, E = 2,
lib = "1 100", pred = "201 500", columns = "TentMap",
target = "TentMap", showPlot = FALSE )

---

Empirical dynamic modeling

Description

rEDM provides tools for data-driven time series analyses. It is based on reconstructing multivariate state space representations from uni or multivariate time series, then projecting state changes using various metrics applied to nearest neighbors.

rEDM is a Rcpp interface to the cppEDM library of Empirical Dynamic Modeling tools. Functionality includes:

• Simplex projection (Sugihara and May 1990)

• Sequential Locally Weighted Global Linear Maps (S-map) (Sugihara 1994)

• Multivariate embeddings (Dixon et. al. 1999)

• Convergent cross mapping (Sugihara et. al. 2012)

• Multiview embedding (Ye and Sugihara 2016)

Details

Main Functions:

• Simplex - simplex projection

• SMap - S-map projection

• CCM - convergent cross mapping

• Multiview - multiview forecasting

Helper Functions:

• Embed - time delay embedding

• ComputeError - forecast skill metrics

• EmbedDimension - optimal embedding dimension

• PredictInterval - optimal prediction interval

• PredictNonlinear - evaluate nonlinearity

Author(s)

Maintainer: Joseph Park

Authors: Joseph Park, Cameron Smith, Ethan Deyle, Erik Saberski, George Sugihara

References

Sugihara G. and May R. 1990. Nonlinear forecasting as a way of distinguishing chaos from measurement error in time series. Nature, 344:734-741.

Sugihara G. 1994. Nonlinear forecasting for the classification of natural time series. Philosophical Transactions: Physical Sciences and Engineering, 348 (1688) : 477-495.

Dixon, P. A., M. Milicich, and G. Sugihara, 1999. Episodic fluctuations in larval supply. Science 283:1528-1530.

Sugihara G., May R., Ye H., Hsieh C., Deyle E., Fogarty M., Munch S., 2012. Detecting Causality in Complex Ecosystems. Science 338:496-500.

Ye H., and G. Sugihara, 2016. Information leverage in interconnected ecosystems: Overcoming the curse of dimensionality. Science 353:922-925.

---

Time series for the California Current Anchovy-Sardine-SST system

Description

Time series of Pacific sardine landings (CA), Northern anchovy landings (CA), and sea-surface temperature (3-year average) at the SIO pier and Newport pier

Usage

sardine_anchovy_sst

Format

year

year of measurement

anchovy

anchovy landings, scaled to mean = 0, sd = 1

sardine

sardine landings, scaled to mean = 0, sd = 1

sio_sst

3-year running average of sea surface temperature at SIO pier, scaled to mean = 0, sd = 1

np_sst

3-year running average of sea surface temperature at Newport pier, scaled to mean = 0, sd = 1

---

Simplex forecasting

Description

Simplex performs time series forecasting based on weighted nearest neighbors projection in the time series phase space as described in Sugihara and May.

Usage

Simplex(pathIn = "./", dataFile = "", dataFrame = NULL, pathOut = "./", 
  predictFile = "", lib = "", pred = "", E = 0, Tp = 1, knn = 0, tau = -1, 
  exclusionRadius = 0, columns = "", target = "", embedded = FALSE,
  verbose = FALSE, validLib = vector(), generateSteps = 0,
  parameterList = FALSE, showPlot = FALSE, noTime = FALSE)

Arguments

pathIn	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values unless noTime is TRUE. The first row must be column names.
dataFrame	input data.frame. The first column must be a time index or time values unless noTime is TRUE. The columns must be named.
pathOut	path for predictFile containing output predictions.
predictFile	output file name.
lib	string or vector with start and stop indices of input data rows used to create the library from observations. Mulitple row index pairs can be specified with each pair defining the first and last rows of time series observation segments used to create the library.
pred	string with start and stop indices of input data rows used for predictions. A single contiguous range is supported.
E	embedding dimension.
Tp	prediction horizon (number of time column rows).
knn	number of nearest neighbors. If knn=0, knn is set to E+1.
tau	lag of time delay embedding specified as number of time column rows.
exclusionRadius	excludes vectors from the search space of nearest neighbors if their relative time index is within exclusionRadius.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
target	column name used for prediction.
embedded	logical specifying if the input data are embedded.
verbose	logical to produce additional console reporting.
validLib	logical vector the same length as the number of data rows. Any data row represented in this vector as FALSE, will not be included in the library.
generateSteps	number of predictive feedback generative steps.
parameterList	logical to add list of invoked parameters.
showPlot	logical to plot results.
noTime	logical to allow input data with no time column.

Details

If embedded is FALSE, the data column(s) are embedded to dimension E with time lag tau. This embedding forms an E-dimensional phase space for the Simplex projection. If embedded is TRUE, the data are assumed to contain an E-dimensional embedding with E equal to the number of columns. Predictions are made using leave-one-out cross-validation, i.e. observation vectors are excluded from the prediction simplex.

To assess an optimal embedding dimension EmbedDimension can be applied. Accuracy statistics can be estimated by ComputeError.

Value

A data.frame with columns Observations, Predictions. The first column contains the time values.

If parameterList = TRUE, a named list with "predictions" holding the data.frame, "parameters" with a named list of invoked parameters.

References

Sugihara G. and May R. 1990. Nonlinear forecasting as a way of distinguishing chaos from measurement error in time series. Nature, 344:734-741.

Examples

data( block_3sp )
smplx = Simplex( dataFrame = block_3sp, lib = "1 100", pred = "101 190",
E = 3, columns = "x_t", target = "x_t" )
ComputeError( smplx $ Predictions, smplx $ Observations )

---

SMap forecasting

Description

SMap performs time series forecasting based on localised (or global) nearest neighbor projection in the time series phase space as described in Sugihara 1994.

Usage

SMap(pathIn = "./", dataFile = "", dataFrame = NULL, 
  lib = "", pred = "", E = 0, Tp = 1, knn = 0, tau = -1, 
  theta = 0, exclusionRadius = 0, columns = "", target = "", 
  embedded = FALSE, verbose = FALSE,
  validLib = vector(), ignoreNan = TRUE,
  generateSteps = 0, parameterList = FALSE,
  showPlot = FALSE, noTime = FALSE)

Arguments

pathIn	path to dataFile.
dataFile	.csv format data file name. The first column must be a time index or time values unless noTime is TRUE. The first row must be column names.
dataFrame	input data.frame. The first column must be a time index or time values unless noTime is TRUE. The columns must be named.
lib	string or vector with start and stop indices of input data rows used to create the library from observations. Mulitple row index pairs can be specified with each pair defining the first and last rows of time series observation segments used to create the library.
pred	string with start and stop indices of input data rows used for predictions. A single contiguous range is supported.
E	embedding dimension.
Tp	prediction horizon (number of time column rows).
knn	number of nearest neighbors. If knn=0, knn is set to the library size.
tau	lag of time delay embedding specified as number of time column rows.
theta	neighbor localisation exponent.
exclusionRadius	excludes vectors from the search space of nearest neighbors if their relative time index is within exclusionRadius.
columns	string of whitespace separated column name(s), or vector of column names used to create the library. If individual column names contain whitespace place names in a vector, or, append ',' to the name.
target	column name used for prediction.
embedded	logical specifying if the input data are embedded.
verbose	logical to produce additional console reporting.
validLib	logical vector the same length as the number of data rows. Any data row represented in this vector as FALSE, will not be included in the library.
ignoreNan	logical to internally redefine library to avoid nan.
generateSteps	number of predictive feedback generative steps.
parameterList	logical to add list of invoked parameters.
showPlot	logical to plot results.
noTime	logical to allow input data with no time column.

Details

If embedded is FALSE, the data column(s) are embedded to dimension E with time lag tau. This embedding forms an n-columns * E-dimensional phase space for the SMap projection. If embedded is TRUE, the data are assumed to contain an E-dimensional embedding with E equal to the number of columns. See the Note below for proper use of multivariate data (number of columns > 1).

If ignoreNan is TRUE, the library (lib) is internally redefined to exclude nan embedding vectors. If ignoreNan is FALSE no library adjustment is made. The (lib) can be explicitly specified to exclude nan library vectors.

Predictions are made using leave-one-out cross-validation, i.e. observation rows are excluded from the prediction regression.

In contrast to Simplex, SMap uses all available neighbors and weights them with an exponential decay in phase space distance with exponent theta. theta=0 uses all neighbors corresponding to a global autoregressive model. As theta increases, neighbors closer in vicinity to the observation are considered.

Value

A named list with three data.frames [[predictions, coefficients, singularValues]]. predictions has columns Observations, Predictions. The first column contains time or index values.

coefficients data.frame has time or index values in the first column. Columns 2 through E+2 (E+1 columns) are the SMap coefficients.

singularValues data.frame has time or index values in the first column. Columns 2 through E+2 (E+1 columns) are the SVD singularValues. The first value corresponds to the SVD bias (intercept) term.

If parameterList = TRUE a named list "parameters" is added.

Note

SMap should be called with columns explicitly corresponding to dimensions E. In the univariate case (number of columns = 1) with default embedded = FALSE, the time series will be time-delay embedded to dimension E, SMap coefficients correspond to each dimension.

If a multivariate data set is used (number of columns > 1) it must use embedded = TRUE with E equal to the number of columns. This prevents the function from internally time-delay embedding the multiple columns to dimension E. If the internal time-delay embedding is performed, then state-space columns will not correspond to the intended dimensions in the matrix inversion, coefficient assignment, and prediction. In the multivariate case, the user should first prepare the embedding (using Embed for time-delay embedding), then pass this embedding to SMap with appropriately specified columns, E, and embedded = TRUE.

References

Sugihara G. 1994. Nonlinear forecasting for the classification of natural time series. Philosophical Transactions: Physical Sciences and Engineering, 348 (1688):477-495.

Examples

data(circle)
L = SMap( dataFrame = circle, lib="1 100", pred="110 190", theta = 4,
E = 2, embedded = TRUE, columns = "x y", target = "x" )

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Generate surrogate data for permutation/randomization tests

Description

SurrogateData generates surrogate data under several different null models.

Usage

SurrogateData( ts, method = c("random_shuffle", "ebisuzaki",
"seasonal"), num_surr = 100, T_period = 1, alpha = 0 )

Arguments

ts	the original time series
method	which algorithm to use to generate surrogate data
num_surr	the number of null surrogates to generate
T_period	the period of seasonality for seasonal surrogates (ignored for other methods)
alpha	additive noise factor: N(0,alpha)

Details

Method "random_shuffle" creates surrogates by randomly permuting the values of the original time series.

Method "Ebisuzaki" creates surrogates by randomizing the phases of a Fourier transform, preserving the power spectra of the null surrogates.

Method "seasonal" creates surrogates by computing a mean seasonal trend of the specified period and shuffling the residuals. It is presumed that the seasonal trend can be exracted with a smoothing spline. Additive Gaussian noise is included according to N(0,alpha).

Value

A matrix where each column is a separate surrogate with the same length as ts.

Examples

data("block_3sp")
ts <- block_3sp$x_t
SurrogateData(ts, method = "ebisuzaki")

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Time series for a tent map with mu = 2.

Description

First-differenced time series generated from the tent map recurrence relation with mu = 2.

Usage

TentMap

Format

Data frame with 999 rows and 2 columns

Time

time index.

TentMap

tent map values.

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Time series of tent map plus noise.

Description

First-differenced time series generated from the tent map recurrence relation with mu = 2 and random noise.

Usage

TentMapNoise

Format

Data frame with 999 rows and 2 columns

Time

time index.

TentMap

tent map values.

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Apple-blossom Thrips time series

Description

Seasonal outbreaks of Thrips imaginis.

References

Davidson and Andrewartha, Annual trends in a natural population of Thrips imaginis Thysanoptera, Journal of Animal Ecology, 17, 193-199, 1948.

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