make.SpatialVx {SpatialVx}

Spatial Verification Sets – SpatialVx Object

Description

A list object containing the verification sets of spatial verification and forecast fields with pertinent information.

Usage

make.SpatialVx(X, Xhat, thresholds = NULL, loc = NULL, projection =
                 FALSE, subset = NULL, time.vals = NULL, reg.grid =
                 TRUE, map = FALSE, loc.byrow = FALSE, field.type = "",
                 units = "", data.name = "", obs.name = "X", model.name
                 = "Xhat", q = c(0, 0.1, 0.25, 0.33, 0.5, 0.66, 0.75,
                 0.9, 0.95), qs = NULL)

## S3 method for class 'SpatialVx'
hist(x, ..., time.point = 1, obs = 1, model = 1,
                 threshold.num = NULL)

## S3 method for class 'SpatialVx'
plot( x, ..., time.point = 1, obs = 1, model = 1,
    col = c( "gray", tim.colors( 64 ) ), zlim, mfrow = c(1, 2) )

## S3 method for class 'SpatialVx'
print(x, ...)

## S3 method for class 'SpatialVx'
summary(object, ...)

Arguments

X

An n X m matrix or n X m X T array giving the verification field of interest. If an array, T is the number of time points.

Xhat

An n X m matrix or n X m X T array giving the forecast field of interest, or a list of such matrices/arrays with each component of the list an n X m matrix or n X m X T array defining a separate forecast model.

thresholds

single numeric, numeric vector, or Nu X Nf matrix, where Nu are the number of thresholds and Nf the number of forecast models plus one (for the verification) giving the threshold values of interest for the verification set or components of the set. If NULL (default), then thresholds will be calculated as the quantiles (defined through argument q) of each field. If a single numeric or a numeric vector, then an n X 2 matrix will be created (with column names “X” and “Xhat” where each column is identical. Otherwise, different thresholds may be applied to each of the verification and forecast fields. For example, if quantiles are used for thresholds, then each field will have their own unique thresholds.

loc

If lon/lat coordinates are available, then this is an n * m X 2 matrix giving the lon/lat coordinates of each grid point or location. Should follow the convention used by the maps package.

projection

logical, are the grids projections onto the globe? If so, when plotting, it will be attempted to account for this by using the poly.image function from package fields. In this case, each column of loc will be converted to a matrix using byrow equal to the value of loc.byrow.

subset

vector identifying which specific grid points should be included (if not all of them). This argument may be ignored by most functions and is included for possible future functionality.

time.vals

If more than one time point is available in the set (i.e., the set is of n X m X T arrays, with T > 1), then this argument can be used to define the time points. If missing, the default will yield the vector 1:T. But, it is possible to include actual time information. This is also a forward looking feature that may or may not have any subsequent functionality.

reg.grid

logical, is the verification set on a regular grid? This is another feature intended for possible future functionality. Most functions in this package assume the set is on a regular grid.

map

logical, should the plot function attempt to place a map onto the plot? Only possible if the loc argument is given.

field.type, units

character used for plot labelling and printing information to the screen. Describes what variable and in what units the field represents.

data.name, obs.name, model.name

character vector describing the verification set overall, the observation(s) and the model(s), resp.

q

numeric vector giving the values of quantiles to be used for thresholds. Only used if thresholds is NULL.

qs

character vector describing the quantiles used. Again, only used if thresholds is NULL. This is for subsequent plot/print labelling purposes.

time.point

numeric or character indicating which time point from the “SpatialVx” verification set to select for analysis. May also be a function name, in which case the function is applied at each grid point individually across time.

obs, model

numeric indicating which observation/forecast model to select for the analysis.

col, zlim

optional arguments to image, and/or fields functions poly.image and image.plot

mfrow

optional argument to change the mfrow argument for the graphic device. Default is one row with two plots (obs and model). If null, then the mfrow argument will not be changed.

x, object

list object of class “SpatialVx”.

loc.byrow

logical determining whether to set up the location matrices using byrow = TRUE or FALSE (for use with poly.image.

threshold.num

If not null, then the threshold index to apply a threshold to the fields before creating the histogram.

...

hist method: optional arguments to hist.

plot method: if time.point is a function, then these allow for optional arguments to this function to be passed.

print and summary methods: Not used.

Details

This function merely describes a spatial verification set that includes the actual data as well as numerous attributes that are used by several of the subsequent functions that might be employed. In many cases, the attribute information may be passed on to output from other functions for plot labelling and printing purposes (e.g., in order to identify the verification set, time point(s), etc.).

All (or perhaps most) subsequent functions in this package utilize objects of this class and the information contained in the attributes. This function simply gathers information and data sets into a particular form.

The plot method function attempts to create an image plot of each field in the set (at each time point). If projection is TRUE, then it will attempt to preserve the projection (via poly.image of package fields). It will also add white contour lines showing the thresholds. If map is TRUE and loc was supplied, then a map will also be added, if possible.

Value

A list object with two (unnamed) components:

1

matrix or array (same as input argument) giving the observation

2

Either a matrix or array (same as input argument) or a list of such objects if more than one forecast model.

Several attributes are also included among the following:

xdim

numeric of length 2 or 3 giving the dimensions of the verification set (i.e., m, n and T, if relevant).

time

vector giving the time values

thresholds

matrix giving the thresholds for each field. If there is more than one forecast, and they use the same threshold, this matrix may have only two columns.

udim

the dimensions of the thresholds matrix.

loc

nm X 2 matrix giving the locations. If loc was not given, this will be c(rep(1:n, m), rep(1:m, each=n)).

subset

If given, this is a numeric vector describing a subset of loc to be used.

data.name, obs.name, model.name

character vector giving the names of the data sets (same as input arguments).

nforecast

single numeric giving the number of different forecast models contained in the object.

field.type, units

character strings, same as input arguments.

projection

logical, is the grid a projection?

reg.grid

logical, is the grid a regular grid?

map

logical, should a map be added to image plots of the data?

qs

character vector giving the names of the threshold quantiles.

msg

A message involving the data name, field type and units for adding info to plots, etc.

Author(s)

Eric Gilleland

See Also

hoods2d, poly.image

Examples

data( "UKobs6" )
data( "UKfcst6" )
data( "UKloc" )

hold <- make.SpatialVx( UKobs6, UKfcst6, thresholds = c(0.01, 20.01),
    loc = UKloc, field.type = "Precipitation", units = "mm/h",
    data.name = "Nimrod", obs.name = "Observations 6", model.name = "Forecast 6",
    map = TRUE)

hold

plot( hold )

hist( hold )

hist( hold, threshold.num = 2 )