Package ncsa.hdf.object
Class Attribute
- java.lang.Object
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- ncsa.hdf.object.Attribute
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- All Implemented Interfaces:
java.io.Serializable
,Metadata
public class Attribute extends java.lang.Object implements Metadata
An attribute is a (name, value) pair of metadata attached to a primary data object such as dataset, group or named datatype.Like a dataset, an attribute has a name, datatype and dataspace.
For more details on attibutes, see {@link HDF5 User's Guide}
The following code is an example of an attribute with 1D integer array of two elements.
// Example of creating a new attribute // The name of the new attribute String name = "Data range"; // Creating an unsigned 1-byte integer datatype Datatype type = new Datatype(Datatype.CLASS_INTEGER, // class 1, // size in bytes Datatype.ORDER_LE, // byte order Datatype.SIGN_NONE); // signed or unsigned // 1-D array of size two long[] dims = {2}; // The value of the attribute int[] value = {0, 255}; // Create a new attribute Attribute dataRange = new Attribute(name, type, dims); // Set the attribute value dataRange.setValue(value); // See FileFormat.writeAttribute() for how to attach an attribute to an object,
- Version:
- 1.1 9/4/2007
- Author:
- Peter X. Cao
- See Also:
FileFormat.writeAttribute(HObject, Attribute, boolean)
,Datatype
, Serialized Form
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Field Summary
Fields Modifier and Type Field Description protected boolean
isScalar
flag to indicate if the dataset is a single scalar point
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Constructor Summary
Constructors Constructor Description Attribute(java.lang.String attrName, Datatype attrType, long[] attrDims)
Create an attribute with specified name, data type and dimension sizes.Attribute(java.lang.String attrName, Datatype attrType, long[] attrDims, java.lang.Object attrValue)
Create an attribute with specific name and value.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description long[]
getDataDims()
Returns the dimension sizes of the data value of the attribute.java.lang.String
getName()
Returns the name of the attribute.java.lang.Object
getProperty(java.lang.String key)
get a property for a given key.java.util.Collection<java.lang.String>
getPropertyKeys()
get all property keys.int
getRank()
Returns the rank (number of dimensions) of the attribute.Datatype
getType()
Returns the datatype of the attribute.java.lang.Object
getValue()
Returns the value of the attribute.boolean
isScalar()
boolean
isUnsigned()
Checks if the data type of this attribute is an unsigned integer.void
setProperty(java.lang.String key, java.lang.Object value)
set a property for the attribute.void
setValue(java.lang.Object theValue)
Sets the value of the attribute.java.lang.String
toString()
Return the name of the attribute.java.lang.String
toString(java.lang.String delimiter)
Returns a string representation of the data value of the attribute.
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Constructor Detail
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Attribute
public Attribute(java.lang.String attrName, Datatype attrType, long[] attrDims)
Create an attribute with specified name, data type and dimension sizes. For scalar attribute, the dimension size can be either an array of size one or null, and the rank can be either 1 or zero. Attribute is a general class and is independent of file format, e.g., the implementation of attribute applies to both HDF4 and HDF5.The following example creates a string attribute with the name "CLASS" and value "IMAGE".
long[] attrDims = { 1 }; String attrName = "CLASS"; String[] classValue = { "IMAGE" }; Datatype attrType = new H5Datatype(Datatype.CLASS_STRING, classValue[0].length() + 1, -1, -1); Attribute attr = new Attribute(attrName, attrType, attrDims); attr.setValue(classValue);
- Parameters:
attrName
- the name of the attribute.attrType
- the datatype of the attribute.attrDims
- the dimension sizes of the attribute, null for scalar attribute- See Also:
Datatype
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Attribute
public Attribute(java.lang.String attrName, Datatype attrType, long[] attrDims, java.lang.Object attrValue)
Create an attribute with specific name and value. For scalar attribute, the dimension size can be either an array of size one or null, and the rank can be either 1 or zero. Attribute is a general class and is independent of file format, e.g., the implementation of attribute applies to both HDF4 and HDF5.The following example creates a string attribute with the name "CLASS" and value "IMAGE".
long[] attrDims = { 1 }; String attrName = "CLASS"; String[] classValue = { "IMAGE" }; Datatype attrType = new H5Datatype( Datatype.CLASS_STRING, classValue[0] .length() + 1, -1, -1); Attribute attr = new Attribute( attrName, attrType, attrDims, classValue);
- Parameters:
attrName
- the name of the attribute.attrType
- the datatype of the attribute.attrDims
- the dimension sizes of the attribute, null for scalar attributeattrValue
- the value of the attribute, null if no value- See Also:
Datatype
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Method Detail
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getValue
public java.lang.Object getValue()
Returns the value of the attribute. For atomic datatype, this will be an 1D array of integers, floats and strings. For compound datatype, it will be an 1D array of strings with field members separated by comma. For example, "{0, 10.5}, {255, 20.0}, {512, 30.0}" is a cmpound attribute of {int, float} of three data points.
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setProperty
public void setProperty(java.lang.String key, java.lang.Object value)
set a property for the attribute.
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getProperty
public java.lang.Object getProperty(java.lang.String key)
get a property for a given key.
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getPropertyKeys
public java.util.Collection<java.lang.String> getPropertyKeys()
get all property keys.
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setValue
public void setValue(java.lang.Object theValue)
Sets the value of the attribute. It returns null if failed to retrieve the name from file.
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getName
public java.lang.String getName()
Returns the name of the attribute.- Returns:
- the name of the attribute.
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getRank
public int getRank()
Returns the rank (number of dimensions) of the attribute. It returns a negative number if failed to retrieve the dimension information from file.- Returns:
- the number of dimensions of the attribute.
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getDataDims
public long[] getDataDims()
Returns the dimension sizes of the data value of the attribute. It returns null if failed to retrieve the dimension information from file.- Returns:
- the dimension sizes of the attribute.
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getType
public Datatype getType()
Returns the datatype of the attribute. It returns null if failed to retrieve the datatype information from file.- Returns:
- the datatype of the attribute.
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isScalar
public boolean isScalar()
- Returns:
- true if the data is a single scalar point; otherwise, returns false.
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isUnsigned
public boolean isUnsigned()
Checks if the data type of this attribute is an unsigned integer.- Returns:
- true if the data type of the attribute is an unsigned integer; otherwise returns false.
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toString
public java.lang.String toString()
Return the name of the attribute.- Overrides:
toString
in classjava.lang.Object
- See Also:
toString(String delimiter)
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toString
public java.lang.String toString(java.lang.String delimiter)
Returns a string representation of the data value of the attribute. For example, "0, 255".For compound datatype, it will be an 1D array of strings with field members separated by comma. For example, "{0, 10.5}, {255, 20.0}, {512, 30.0}" is a compound attribute of {int, float} of three data points.
- Parameters:
delimiter
- The delimiter to separate individual data point. It can be comma, semicolon, tab or space. For example, to String(",") will separate data by comma.- Returns:
- the string representation of the data values.
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