Package uk.ac.starlink.ttools.plot2.data
Interface DataSpec
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- All Known Implementing Classes:
AbstractDataSpec
,ColumnDataSpec
,JELDataSpec
@Equality public interface DataSpec
Defines the table-like data that is required for a certain plot. This object does not store the data itself, but can be passed to aDataStore
object to obtain it. A DataSpec has a small memory footprint, is cheap to produce, and can be examined to determine what data is required.The data specification is an aggregation of the following items:
- The table the data comes from
- A list of the columns, or column-like objects, used from the table
- An identifier for a mask indicating which rows from the table will be included
Two DataSpecs should evaluate equal if their specification of the above items have the same content, that is if they would generate the same
TupleSequence
when presented to aDataStore
.- Since:
- 7 Feb 2013
- Author:
- Mark Taylor
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description UserDataReader
createUserDataReader()
Returns an object that can be used to read the mask and coordinate values from a row sequence derived from this object's source table.Coord
getCoord(int icoord)
Returns the coord reader that can read the data for one of this object's output columns.int
getCoordCount()
Returns the number of columns that this object produces.java.lang.Object
getCoordId(int icoord)
Returns an identifier for one of the the columns produced by this object.java.lang.Object
getMaskId()
Returns an identifier for the row mask for this object.uk.ac.starlink.table.StarTable
getSourceTable()
Returns the table object from which this data spec's data is obtained.uk.ac.starlink.table.ValueInfo[]
getUserCoordInfos(int icoord)
Returns the metadata, if known, for the values supplied by the user to provide data for one of this object's output columns.boolean
isCoordBlank(int icoord)
Indicates whether the value for a given coord specified by this object is known to have a constant, blank value in all cases.
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Method Detail
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getSourceTable
uk.ac.starlink.table.StarTable getSourceTable()
Returns the table object from which this data spec's data is obtained.- Returns:
- data source table
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getCoordCount
int getCoordCount()
Returns the number of columns that this object produces.- Returns:
- TupleSequence column count
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getMaskId
java.lang.Object getMaskId()
Returns an identifier for the row mask for this object.- Returns:
- mask identifier, should implement equals sensibly
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getCoordId
java.lang.Object getCoordId(int icoord)
Returns an identifier for one of the the columns produced by this object.- Parameters:
icoord
- column index- Returns:
- column identifier, should implement equals sensibly
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getCoord
Coord getCoord(int icoord)
Returns the coord reader that can read the data for one of this object's output columns.- Parameters:
icoord
- column index- Returns:
- column data reader
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getUserCoordInfos
uk.ac.starlink.table.ValueInfo[] getUserCoordInfos(int icoord)
Returns the metadata, if known, for the values supplied by the user to provide data for one of this object's output columns.- Parameters:
icoord
- column index- Returns:
- array of value infos for column data; elements may be null if not known
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createUserDataReader
UserDataReader createUserDataReader()
Returns an object that can be used to read the mask and coordinate values from a row sequence derived from this object's source table. A given UserDataReader can only be used from a single thread, but multiple returns from this method may be used concurrently in different threads.- Returns:
- new data reader
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isCoordBlank
boolean isCoordBlank(int icoord)
Indicates whether the value for a given coord specified by this object is known to have a constant, blank value in all cases. Clients don't have to test this, since data stores will always dispense the relevant blank value based on this data spec, and should do so in an efficient manner, but it may be useful for clients to know in advance that a column is blank all the way down. False negatives are permitted: even if the result is false, the column may in fact have all blank values.- Parameters:
icoord
- column index- Returns:
- true if all values in the column are always blank
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