Package uk.ac.starlink.table
Class Tables
- java.lang.Object
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- uk.ac.starlink.table.Tables
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public class Tables extends java.lang.Object
Utility class for miscellaneous table-related functionality.
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Field Summary
Fields Modifier and Type Field Description static DefaultValueInfo
DEC_INFO
ValueInfo representing Declination.static ValueInfo
NULL_VALUE_INFO
ValueInfo which may be used as part of a column's metadata to indicate a special value (preferably aNumber
that should be interpreted as a null (blank).static DefaultValueInfo
RA_INFO
ValueInfo representing Right Ascension.static ValueInfo
UBYTE_FLAG_INFO
ValueInfo which may be used as part of a column's auxiliary metadata to indicate that the column's data represents, and can be serialised as, unsigned byte values.
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Constructor Summary
Constructors Constructor Description Tables()
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Method Summary
All Methods Static Methods Concrete Methods Deprecated Methods Modifier and Type Method Description static TableSequence
arrayTableSequence(StarTable[] tables)
Convenience method to construct a TableSequence for a supplied array of tables.static int
assertLongToInt(long lval)
Casts a long to an int, with an assertion that no truncation occurs.static int
checkedLongToInt(long lval)
Convenience method to get an int value from a long.static long
checksumData(RowSequence rseq, java.util.zip.Checksum checksum)
Feeds the data from a row sequence to a supplied checksum accumulator.static int
checksumData(StarTable table)
Returns a checksum of all the cell data in a given table.static void
checkTable(StarTable table)
Diagnostic method which tests the invariants of a StarTable.static java.lang.String
collapseWhitespace(java.lang.String txt)
Collapses whitespace in a string.static StarTable
deleteColumn(StarTable startab, int icol)
Returns a table equivalent to the original but with a given column deleted.static void
fixColumns(ColumnInfo[][] infoLists, JoinFixAction[] fixActs)
Performs deduplication of column names for N lists of column metadata objects that will be combined to form a new table.static <T> T
getAuxDatumValue(ValueInfo info, ValueInfo auxKey, java.lang.Class<T> auxClazz)
Utility method to return an auxiliary metadata item from a ValueInfo.static ColumnInfo[]
getColumnInfos(StarTable startab)
Convenience method to return an array of all the column headers in a given table.static RowSplittable
getDefaultRowSplittable(StarTable table)
Returns a RowSplittable object with generic characteristics for a given table.static DescribedValue
getDescribedValueByName(java.util.Collection<DescribedValue> dvals, java.lang.String name)
Utility method to locate an element in a list of DescribedValue given the name of its ValueInfo member.static java.lang.String[]
getElementLabels(int[] shape)
Returns an array of strings suitable as labels or label suffixes for elements of an array as returned byValueInfo.getShape()
.static <T> T
getTypedValue(DescribedValue dval, java.lang.Class<T> clazz)
Utility method to get a typed value from a, possibly null, described value.static java.lang.String
getUtype(ValueInfo info)
Deprecated.useValueInfo.getUtype()
insteadstatic java.lang.Object
getValue(java.util.Collection<DescribedValue> dvals, ValueInfo info)
Returns the value from a list ofDescribedValue
objects which corresponds to a given info key.static java.lang.String
getXtype(ValueInfo info)
Deprecated.useValueInfo.getXtype()
insteadstatic boolean
isBlank(java.lang.Object value)
Indicates whether a given value is conventionally regarded as a blank value.static StarTable
randomTable(StarTable startab)
Returns a table based on a given table and guaranteed to have random access.static void
setDescribedValue(java.util.Collection<DescribedValue> dvals, DescribedValue dval)
Utility method to update a list of DescribedValues with a new entry.static void
setUtype(ValueInfo info, java.lang.String utype)
Deprecated.useDefaultValueInfo.setUtype(java.lang.String)
insteadstatic void
setXtype(ValueInfo info, java.lang.String xtype)
Deprecated.useDefaultValueInfo.setXtype(java.lang.String)
insteadstatic TableSequence
singleTableSequence(StarTable table)
Convenience method to construct a TableSequence for a single table.static StarTable
sortTable(StarTable table, int[] colIndices, boolean up, boolean nullsLast)
Returns a sorted version of a table.static void
streamStarTable(StarTable source, TableSink sink)
Copies the data and metadata from a StarTable into a table sink.static StarTable[]
tableArray(TableSequence tseq)
Convenience method to construct an array of StarTables from a TableSequence.static java.lang.String
tableToString(StarTable table, java.lang.String ofmt)
Returns the contents of a table as a string.
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Field Detail
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NULL_VALUE_INFO
public static final ValueInfo NULL_VALUE_INFO
ValueInfo which may be used as part of a column's metadata to indicate a special value (preferably aNumber
that should be interpreted as a null (blank). This should only be used on nullable columns, and really only on ones with a contentClass which is an integer (or possibly boolean) type; for other types, there is usually a value which can conventionally be understood to mean blank. Note this is here as a standard key to use when software components wish to communicate this information; the table system does not guarantee to honour instances of this value in a column's auxiliary data. It is the job of a StarTable instance to ensure that a null is returned from the table interrogation methods if that is what is meant.
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UBYTE_FLAG_INFO
public static final ValueInfo UBYTE_FLAG_INFO
ValueInfo which may be used as part of a column's auxiliary metadata to indicate that the column's data represents, and can be serialised as, unsigned byte values. If so, the value is set toBoolean.TRUE
(other values are treated as if absent). Data representing unsigned byte values will normally be represented within STIL by Short (16-bit integer) signed values, since there is no unsigned byte type in java. However, this flag may be used to indicate that the values can be serialised to unsigned-byte-capable output formats (for instance FITS and VOTable) using an unsigned byte serialisation. This annotation will normally only be honoured if the data type of the column is (scalar or array) short integer (16-bit) values. Some care should be exercised in applying this flag or (especially) modifying values in columns it applies to, that the actual column value range remains in the unsigned byte data range (0..255), since otherwise problems will result if it is serialised.
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RA_INFO
public static final DefaultValueInfo RA_INFO
ValueInfo representing Right Ascension. The units are radians and it is non-nullable.
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DEC_INFO
public static final DefaultValueInfo DEC_INFO
ValueInfo representing Declination. The units are radians and it is non-nullable.
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Method Detail
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randomTable
public static StarTable randomTable(StarTable startab) throws java.io.IOException
Returns a table based on a given table and guaranteed to have random access. If the original table stab has random access then it is returned, otherwise a new random access table is built using its data.This convenience method is equivalent to calling StoragePolicy.getDefaultPolicy().randomTable(startab).
- Parameters:
startab
- original table- Returns:
- a table with the same data as startab and with isRandom()==true
- Throws:
java.io.IOException
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getColumnInfos
public static ColumnInfo[] getColumnInfos(StarTable startab)
Convenience method to return an array of all the column headers in a given table. Modifying this array will not affect the table.- Parameters:
startab
- the table being enquired about- Returns:
- an array of all the column headers
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deleteColumn
public static StarTable deleteColumn(StarTable startab, int icol)
Returns a table equivalent to the original but with a given column deleted. The result may or may not be the same object as the input table.- Parameters:
startab
- the table from which to delete a columnicol
- the index of the column to be deleted- Throws:
java.lang.IndexOutOfBoundsException
- if startab has no column at icol
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streamStarTable
public static void streamStarTable(StarTable source, TableSink sink) throws java.io.IOException
Copies the data and metadata from a StarTable into a table sink. This method is supplied for convenience; its implementation is very straightforward.- Parameters:
source
- table to be copiedsink
- table destination- Throws:
java.io.IOException
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getDefaultRowSplittable
public static RowSplittable getDefaultRowSplittable(StarTable table) throws java.io.IOException
Returns a RowSplittable object with generic characteristics for a given table. For a random-access table the splitting will be based onRowAccess
objects, and for a non-random table it will not be capable of splits.- Parameters:
table
- table- Returns:
- splittable for potentially parallel iteration over rows
- Throws:
java.io.IOException
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checkTable
public static void checkTable(StarTable table) throws java.io.IOException
Diagnostic method which tests the invariants of a StarTable. This method returns no value, and throws an exception if a table is illegal in some way. If this method throws an exception when called on a given StarTable, that table is deemed to be bad in some way (buggy implementation or I/O trouble during access). This method is provided for convenience and diagnostics because there are a number of ways, some of them subtle, in which a StarTable can fail to fulfil its general contract.That a table passes this test does not guarantee that the table has no bugs. This method should not generally be used in production code, since it may be expensive in time and/or memory.
- Parameters:
table
- table to test- Throws:
java.lang.AssertionError
- if an invariant is violatedjava.io.IOException
- if there is an I/O error
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checksumData
public static int checksumData(StarTable table) throws java.io.IOException
Returns a checksum of all the cell data in a given table. Currently, the Adler32 checksum is used.- Parameters:
table
- table to checksum- Returns:
- checksum value
- Throws:
java.io.IOException
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checksumData
public static long checksumData(RowSequence rseq, java.util.zip.Checksum checksum) throws java.io.IOException
Feeds the data from a row sequence to a supplied checksum accumulator.- Parameters:
rseq
- row sequence containing datachecksum
- checksum accumulator- Returns:
- number of rows checksummed (note this is not the checksum value)
- Throws:
java.io.IOException
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isBlank
public static boolean isBlank(java.lang.Object value)
Indicates whether a given value is conventionally regarded as a blank value. For most objects this is equivalent to testing whether it is equall to null, but some classes have additional non-null values which count as blanks, for instance zero-length Strings and floating Not-A-Number values.- Parameters:
value
- value to test- Returns:
- true iff value counts as a blank value
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collapseWhitespace
public static java.lang.String collapseWhitespace(java.lang.String txt)
Collapses whitespace in a string. This normalises the text in the sense of the XML Schema facetwhitespace='collapse'
: leading and trailing whitespace is removed, and any other run of whitespace is replaced by a single space character.- Parameters:
txt
- input string (may be null)- Returns:
- string with whitespaces collapsed
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singleTableSequence
public static TableSequence singleTableSequence(StarTable table)
Convenience method to construct a TableSequence for a single table.- Parameters:
table
- table- Returns:
- table sequence with just one element
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arrayTableSequence
public static TableSequence arrayTableSequence(StarTable[] tables)
Convenience method to construct a TableSequence for a supplied array of tables.- Parameters:
tables
- table array- Returns:
- table sequence containing input tables
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tableArray
public static StarTable[] tableArray(TableSequence tseq) throws java.io.IOException
Convenience method to construct an array of StarTables from a TableSequence.- Parameters:
tseq
- table sequence- Returns:
- array containing tables from sequence
- Throws:
java.io.IOException
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sortTable
public static StarTable sortTable(StarTable table, int[] colIndices, boolean up, boolean nullsLast) throws java.io.IOException
Returns a sorted version of a table. The sorting is done on the values of one or more columns, as specified by the colIndices argument; the first element is the primary sort key, but in case of a tie the second element is used, and so on. The original table is not affected. The natural comparison order of the values in the table is used, and blank values may be ranked at the start or end of the collation order.- Parameters:
table
- table to sort - must be random accesscolIndices
- indices of the columns which are to act as sort keys; first element is primary key etcup
- true for sorting into ascending order, false for descending ordernullsLast
- true if blank values should be considered last in the collation order, false if they should be considered first- Returns:
- a table with the same rows as table but in an order determined by the other arguments
- Throws:
java.io.IOException
- if table.isRandom is not true
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tableToString
public static java.lang.String tableToString(StarTable table, java.lang.String ofmt)
Returns the contents of a table as a string. Only intended for small tables, for instance during debugging.- Parameters:
table
- input tableofmt
- output format specifier, or null for plain text output- Returns:
- stringified table
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checkedLongToInt
public static int checkedLongToInt(long lval)
Convenience method to get an int value from a long. If the supplied long integer lval is out of the range which can be represented in an int, then unlike a typecast, this method will throw an IllegalArgumentException.- Parameters:
lval
- the long value to convert- Returns:
- an int value which has the same value as lval
- Throws:
java.lang.IllegalArgumentException
- if the conversion cannot be done
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assertLongToInt
public static int assertLongToInt(long lval)
Casts a long to an int, with an assertion that no truncation occurs.- Parameters:
lval
- long value, asserted to be in the range Integer.MIN_VALUE..Integer.MAX_VALUE- Returns:
- truncated version of
lval
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getElementLabels
public static java.lang.String[] getElementLabels(int[] shape)
Returns an array of strings suitable as labels or label suffixes for elements of an array as returned byValueInfo.getShape()
. If the given shape cannot be decomposed into a fixed size array, returns null.- Parameters:
shape
- vector giving dimensions of an array value- Returns:
- array with one element for each element of the array values (in their natural order), or null for non-array shapes
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getUtype
@Deprecated public static java.lang.String getUtype(ValueInfo info)
Deprecated.useValueInfo.getUtype()
insteadReturns the Utype associated with a given metadata item.- Parameters:
info
- metadata item- Returns:
- utype string, or null if none is available
- See Also:
setUtype(uk.ac.starlink.table.ValueInfo, java.lang.String)
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setUtype
@Deprecated public static void setUtype(ValueInfo info, java.lang.String utype)
Deprecated.useDefaultValueInfo.setUtype(java.lang.String)
insteadTries to set the Utype for a given metadata item.- Parameters:
info
- metadata itemutype
- new utype value- See Also:
getUtype(uk.ac.starlink.table.ValueInfo)
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getXtype
@Deprecated public static java.lang.String getXtype(ValueInfo info)
Deprecated.useValueInfo.getXtype()
insteadReturns the extended type value associated with a given metadata item. The XType corresponds to thextype
attribute of the VOTable format. Other table formats may or may not be able to represent it.- Parameters:
info
- metadata item- Returns:
- xtype string, or null if none is available
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setXtype
@Deprecated public static void setXtype(ValueInfo info, java.lang.String xtype)
Deprecated.useDefaultValueInfo.setXtype(java.lang.String)
insteadTries to set the Xtype for a given metadata item.- Parameters:
info
- metadata itemxtype
- new xtype value- See Also:
getXtype(uk.ac.starlink.table.ValueInfo)
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setDescribedValue
public static void setDescribedValue(java.util.Collection<DescribedValue> dvals, DescribedValue dval)
Utility method to update a list of DescribedValues with a new entry. If an item with the same name as the new entry already exists, it is removed.- Parameters:
dvals
- list to modifydval
- new entry to add
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getDescribedValueByName
public static DescribedValue getDescribedValueByName(java.util.Collection<DescribedValue> dvals, java.lang.String name)
Utility method to locate an element in a list of DescribedValue given the name of its ValueInfo member.- Parameters:
dvals
- list to queryname
- required value of name- Returns:
- element of
dvals
for whichgetInfo().getName()
matchesname
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getAuxDatumValue
public static <T> T getAuxDatumValue(ValueInfo info, ValueInfo auxKey, java.lang.Class<T> auxClazz)
Utility method to return an auxiliary metadata item from a ValueInfo.- Parameters:
info
- metadata itemauxKey
- info identifying aux metadata entry ininfo
auxClazz
- required result type- Returns:
- typed aux metadata item requested, or null if it doesn't exist or has the wrong type
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getTypedValue
public static <T> T getTypedValue(DescribedValue dval, java.lang.Class<T> clazz)
Utility method to get a typed value from a, possibly null, described value.- Parameters:
dval
- described value, or nullclazz
- required return type- Returns:
- typed value of
dval
, or null if dval is null, or if dval's value has the wrong type
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getValue
public static java.lang.Object getValue(java.util.Collection<DescribedValue> dvals, ValueInfo info)
Returns the value from a list ofDescribedValue
objects which corresponds to a given info key. If the key is not represented in the list, or if its value is null, then null is returned.- Parameters:
dvals
- list of DescribedValue objectsinfo
- key giving the value you want- Returns:
- matching value
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fixColumns
public static void fixColumns(ColumnInfo[][] infoLists, JoinFixAction[] fixActs)
Performs deduplication of column names for N lists of column metadata objects that will be combined to form a new table. The arguments are matched arrays; each list of column infos has a corresponding renaming policy. The ColumnInfo objects are renamed in place as required.- Parameters:
infoLists
- array of N arrays of column metadata objectsfixActs
- array of N policies for renaming columns
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