CFAxis: CF axis object
In ncdfCF: Easy Access to NetCDF Files with CF Metadata Conventions
CFAxis R Documentation
CF axis object
Description
This class is a basic ancestor to all classes that represent CF
axes. More useful classes use this class as ancestor.
This super-class does manage the "coordinates" of the axis, i.e. the values
along the axis. This could be the values of the axis as stored on file, but
it can also be the values from an auxiliary coordinate set, in the form of
a CFLabel instance. The coordinate set to use in display, selection and
processing is selectable through methods and fields in this class.
Super class
ncdfCF::CFObject -> CFAxis
Public fields
NCdimThe NCDimension that stores the netCDF dimension details.
This is NULL for CFAxisScalar instances.
orientationA character "X", "Y", "Z" or "T" to indicate the
orientation of the axis, or an empty string if not known or different.
boundsThe boundary values of this axis, if set.
Active bindings
friendlyClassName(read-only) A nice description of the class.
dimid(read-only) The netCDF dimension id of this axis.
length(read-only) The declared length of this axis.
values(read-only) Retrieve the raw values of the axis. In general
you should use the coordinates field rather than this one.
coordinates(read-only) Retrieve the coordinate values of the
active coordinate set from the axis.
auxiliarySet or retrieve auxiliary coordinates for the axis. On
assignment, the value must be an instance of CFLabel or a CFAxis
descendant, which is added to the end of the list of coordinate sets.
On retrieval, the active CFLabel or CFAxis instance or NULL when
the active coordinate set is the primary axis coordinates.
coordinate_namesRetrieve the names of the coordinates
defined for the axis, as a character vector. The first element in the
vector is the name of the axis and it refers to the values of the
coordinates as stored in the netCDF file. Following elements refer to
auxiliary coordinates.
active_coordinatesSet or retrieve the name of the coordinate set
to use with the axis for printing to the console as well as for
processing methods such as subset().
unlimited(read-only) Logical to indicate if the axis has an
unlimited dimension.
Methods
Public methods
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Inherited methods
Method new()
Create a new CF axis instance from a dimension and a
variable in a netCDF resource. This method is called upon opening a
netCDF resource by the initialize() method of a descendant class
suitable for the type of axis.
Usage
CFAxis$new(grp, nc_var, nc_dim, orientation)
Arguments
grpThe NCGroup that this axis is located in.
nc_varThe NCVariable instance upon which this CF axis is based.
nc_dimThe NCDimension instance upon which this CF axis is
based.
orientationThe orientation of the axis: "X", "Y", "Z" "T", or ""
when not known or relevant.
Returns
A basic CFAxis object.
Method print()
Prints a summary of the axis to the console. This method is
typically called by the print() method of descendant classes.
Usage
CFAxis$print(...)
Arguments
...Arguments passed on to other functions. Of particular interest
is width = to indicate a maximum width of attribute columns.
Returns
self, invisibly.
Method brief()
Some details of the axis.
Usage
CFAxis$brief()
Returns
A 1-row data.frame with some details of the axis.
Method shard()
Very concise information on the axis. The information
returned by this function is very concise and most useful when combined
with similar information from other axes.
Usage
CFAxis$shard()
Returns
Character string with very basic axis information.
Method peek()
Retrieve interesting details of the axis.
Usage
CFAxis$peek(with_groups = TRUE)
Arguments
with_groupsShould group information be included? The save option
is TRUE (default) when the netCDF resource has groups because names may
be duplicated among objects in different groups.
Returns
A 1-row data.frame with details of the axis.
Method time()
Return the CFTime instance that represents time. This
method is only useful for CFAxisTime instances and CFAxisScalar
instances having time information. This stub is here to make the call
to this method succeed with no result for the other axis descendants.
Usage
CFAxis$time()
Returns
NULL
Method subset()
Return an axis spanning a smaller coordinate range. This
method is "virtual" in the sense that it does not do anything other
than return NULL. This stub is here to make the call to this method
succeed with no result for the other axis descendants that do not
implement this method.
Usage
CFAxis$subset(group, rng = NULL)
Arguments
groupThe group to create the new axis in.
rngThe range of values from this axis to include in the returned
axis. If the value of the argument is NULL, return the entire axis
(possibly as a scalar axis).
Returns
NULL
Method indexOf()
Find indices in the axis domain. Given a vector of
numerical, timestamp or categorical values x, find their indices in
the values of the axis. With method = "constant" this returns the
index of the value lower than the supplied values in x. With
method = "linear" the return value includes any fractional part.
If bounds are set on the numerical or time axis, the indices are taken
from those bounds. Returned indices may fall in between bounds if the
latter are not contiguous, with the exception of the extreme values in
x.
Usage
CFAxis$indexOf(x, method = "constant")
Arguments
xVector of numeric, timestamp or categorial values to find axis
indices for. The timestamps can be either character, POSIXct or Date
vectors. The type of the vector has to correspond to the type of the
axis.
methodSingle character value of "constant" or "linear".
Returns
Numeric vector of the same length as x. If method = "constant",
return the index value for each match. If method = "linear", return
the index value with any fractional value. Values of x outside of the
range of the values in the axis are returned as 0 and
.Machine$integer.max, respectively.
Method write()
Write the axis to a netCDF file, including its attributes.
Usage
CFAxis$write(nc = NULL)
Arguments
ncThe handle of the netCDF file opened for writing or a group in
the netCDF file. If NULL, write to the file or group where the axis
was read from (the file must have been opened for writing). If not
NULL, the handle to a netCDF file or a group therein.
Returns
Self, invisibly.
Method clone()
The objects of this class are cloneable with this method.
Usage
CFAxis$clone(deep = FALSE)
Arguments
deepWhether to make a deep clone.
ncdfCF documentation built on April 16, 2025, 9:08 a.m.
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| CFAxis | R Documentation |
CF axis object
Description
This class is a basic ancestor to all classes that represent CF axes. More useful classes use this class as ancestor.
This super-class does manage the "coordinates" of the axis, i.e. the values along the axis. This could be the values of the axis as stored on file, but it can also be the values from an auxiliary coordinate set, in the form of a CFLabel instance. The coordinate set to use in display, selection and processing is selectable through methods and fields in this class.
Super class
ncdfCF::CFObject -> CFAxis
Public fields
NCdimThe NCDimension that stores the netCDF dimension details. This is
NULLfor CFAxisScalar instances.orientationA character "X", "Y", "Z" or "T" to indicate the orientation of the axis, or an empty string if not known or different.
boundsThe boundary values of this axis, if set.
Active bindings
friendlyClassName(read-only) A nice description of the class.
dimid(read-only) The netCDF dimension id of this axis.
length(read-only) The declared length of this axis.
values(read-only) Retrieve the raw values of the axis. In general you should use the
coordinatesfield rather than this one.coordinates(read-only) Retrieve the coordinate values of the active coordinate set from the axis.
auxiliarySet or retrieve auxiliary coordinates for the axis. On assignment, the value must be an instance of CFLabel or a CFAxis descendant, which is added to the end of the list of coordinate sets. On retrieval, the active
CFLabelorCFAxisinstance orNULLwhen the active coordinate set is the primary axis coordinates.coordinate_namesRetrieve the names of the coordinates defined for the axis, as a character vector. The first element in the vector is the name of the axis and it refers to the values of the coordinates as stored in the netCDF file. Following elements refer to auxiliary coordinates.
active_coordinatesSet or retrieve the name of the coordinate set to use with the axis for printing to the console as well as for processing methods such as
subset().unlimited(read-only) Logical to indicate if the axis has an unlimited dimension.
Methods
Public methods
Inherited methods
Method new()
Create a new CF axis instance from a dimension and a
variable in a netCDF resource. This method is called upon opening a
netCDF resource by the initialize() method of a descendant class
suitable for the type of axis.
Usage
CFAxis$new(grp, nc_var, nc_dim, orientation)
Arguments
grpThe NCGroup that this axis is located in.
nc_varThe NCVariable instance upon which this CF axis is based.
nc_dimThe NCDimension instance upon which this CF axis is based.
orientationThe orientation of the axis: "X", "Y", "Z" "T", or "" when not known or relevant.
Returns
A basic CFAxis object.
Method print()
Prints a summary of the axis to the console. This method is
typically called by the print() method of descendant classes.
Usage
CFAxis$print(...)
Arguments
...Arguments passed on to other functions. Of particular interest is
width = to indicate a maximum width of attribute columns.
Returns
self, invisibly.
Method brief()
Some details of the axis.
Usage
CFAxis$brief()
Returns
A 1-row data.frame with some details of the axis.
Method shard()
Very concise information on the axis. The information returned by this function is very concise and most useful when combined with similar information from other axes.
Usage
CFAxis$shard()
Returns
Character string with very basic axis information.
Method peek()
Retrieve interesting details of the axis.
Usage
CFAxis$peek(with_groups = TRUE)
Arguments
with_groupsShould group information be included? The save option is
TRUE(default) when the netCDF resource has groups because names may be duplicated among objects in different groups.
Returns
A 1-row data.frame with details of the axis.
Method time()
Return the CFTime instance that represents time. This
method is only useful for CFAxisTime instances and CFAxisScalar
instances having time information. This stub is here to make the call
to this method succeed with no result for the other axis descendants.
Usage
CFAxis$time()
Returns
NULL
Method subset()
Return an axis spanning a smaller coordinate range. This
method is "virtual" in the sense that it does not do anything other
than return NULL. This stub is here to make the call to this method
succeed with no result for the other axis descendants that do not
implement this method.
Usage
CFAxis$subset(group, rng = NULL)
Arguments
groupThe group to create the new axis in.
rngThe range of values from this axis to include in the returned axis. If the value of the argument is
NULL, return the entire axis (possibly as a scalar axis).
Returns
NULL
Method indexOf()
Find indices in the axis domain. Given a vector of
numerical, timestamp or categorical values x, find their indices in
the values of the axis. With method = "constant" this returns the
index of the value lower than the supplied values in x. With
method = "linear" the return value includes any fractional part.
If bounds are set on the numerical or time axis, the indices are taken
from those bounds. Returned indices may fall in between bounds if the
latter are not contiguous, with the exception of the extreme values in
x.
Usage
CFAxis$indexOf(x, method = "constant")
Arguments
xVector of numeric, timestamp or categorial values to find axis indices for. The timestamps can be either character, POSIXct or Date vectors. The type of the vector has to correspond to the type of the axis.
methodSingle character value of "constant" or "linear".
Returns
Numeric vector of the same length as x. If method = "constant",
return the index value for each match. If method = "linear", return
the index value with any fractional value. Values of x outside of the
range of the values in the axis are returned as 0 and
.Machine$integer.max, respectively.
Method write()
Write the axis to a netCDF file, including its attributes.
Usage
CFAxis$write(nc = NULL)
Arguments
ncThe handle of the netCDF file opened for writing or a group in the netCDF file. If
NULL, write to the file or group where the axis was read from (the file must have been opened for writing). If notNULL, the handle to a netCDF file or a group therein.
Returns
Self, invisibly.
Method clone()
The objects of this class are cloneable with this method.
Usage
CFAxis$clone(deep = FALSE)
Arguments
deepWhether to make a deep clone.
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