TimeMapper (Starjava Table API)

java.lang.Object
- uk.ac.starlink.table.TimeMapper

All Implemented Interfaces:

DomainMapper
```
public abstract class TimeMapper
extends java.lang.Object
implements DomainMapper
```
DomainMapper for mapping values to epochs in a common time scale. The target domain is doubles giving the number of seconds since the Unix epoch (1970-01-01T00:00:00). The time scale is generally assumed to be UTC, though conversions may not always be performed, for instance for values in which the intended time scale is not obvious.
A java (IEEE 754) double has 52+1 bits of precision, which I make 52*ln(2)/ln(10)=15.65 decimal places, and a year contains 3.15e7 seconds, which gives you the following precisions:
- epoch +/- 1.7 months: 1 nanosecond precision
- epoch +/- 140 years: 1 microsecond precision
- epoch +/- 140 kyears: 1 millisecond precision
- epoch +/- 140 Myears: 1 second precision
That means around microsecond precision for values near the current epoch (unless this software proves more long lasting than I anticipate). It should be OK for most purposes.
Since:

12 Aug 2013

Author:

Mark Taylor

Field Summary

Fields
Modifier and Type	Field	Description
`static TimeMapper`	`DECIMAL_YEAR`	Mapper for numeric values in decimal year (since 0 AD).
`static TimeMapper`	`ISO_8601`	Mapper for ISO-8601 strings.
`static TimeMapper`	`JD`	Mapper for numeric values in Julian Day.
`static TimeMapper`	`MJD`	Mapper for numeric values in Modified Julian Date.
`static java.lang.String`	`TARGET_NAME`	Returns target domain name ("Time").
`static TimeMapper`	`UNIX_SECONDS`	Mapper for numeric values (already) in unix seconds.

Constructor Summary

Constructors
Modifier	Constructor	Description
`protected`	`TimeMapper(java.lang.Class sourceClass, java.lang.String sourceName, java.lang.String sourceDescription)`	Constructor.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`java.lang.Class`	`getSourceClass()`	Returns the type of values from which this mapper instance can convert.
`java.lang.String`	`getSourceDescription()`	Returns a description of the type of source values which this mapper can convert from.
`java.lang.String`	`getSourceName()`	Returns a short name for the type of source values which this mapper can convert from.
`java.lang.String`	`getTargetName()`	Returns `TARGET_NAME`.
`static TimeMapper[]`	`getTimeMappers()`	Returns a selection of time mapper instances.
`abstract double`	`toUnixSeconds(java.lang.Object sourceValue)`	Maps a source value to time in seconds since the Unix epoch.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - TARGET_NAME
```
public static final java.lang.String TARGET_NAME
```
    Returns target domain name ("Time").
    
    See Also:
    
    Constant Field Values
  - DECIMAL_YEAR
```
public static final TimeMapper DECIMAL_YEAR
```
    Mapper for numeric values in decimal year (since 0 AD).
  - MJD
```
public static final TimeMapper MJD
```
    Mapper for numeric values in Modified Julian Date.
  - JD
```
public static final TimeMapper JD
```
    Mapper for numeric values in Julian Day.
  - UNIX_SECONDS
```
public static final TimeMapper UNIX_SECONDS
```
    Mapper for numeric values (already) in unix seconds.
  - ISO_8601
```
public static final TimeMapper ISO_8601
```
    Mapper for ISO-8601 strings.
- Constructor Detail
  - TimeMapper
```
protected TimeMapper(java.lang.Class sourceClass,
                     java.lang.String sourceName,
                     java.lang.String sourceDescription)
```
    Constructor.
    
    Parameters:
    
    sourceClass -
    
    sourceName - source type name
    
    sourceDescription - source type description
- Method Detail
  - getTargetName
```
public final java.lang.String getTargetName()
```
    Returns TARGET_NAME.
    
    Specified by:
    
    getTargetName in interface DomainMapper
    
    Returns:
    
    domain identifier
  - getSourceClass
```
public java.lang.Class getSourceClass()
```
    Description copied from interface: DomainMapper
    
    Returns the type of values from which this mapper instance can convert.
    
    Specified by:
    
    getSourceClass in interface DomainMapper
    
    Returns:
    
    class of mapper source objects to which this mapper can be applied
  - getSourceName
```
public java.lang.String getSourceName()
```
    Description copied from interface: DomainMapper
    
    Returns a short name for the type of source values which this mapper can convert from.
    
    Specified by:
    
    getSourceName in interface DomainMapper
    
    Returns:
    
    mapper source type name
  - getSourceDescription
```
public java.lang.String getSourceDescription()
```
    Description copied from interface: DomainMapper
    
    Returns a description of the type of source values which this mapper can convert from.
    
    Specified by:
    
    getSourceDescription in interface DomainMapper
    
    Returns:
    
    mapper source type description
  - toUnixSeconds
```
public abstract double toUnixSeconds(java.lang.Object sourceValue)
```
    Maps a source value to time in seconds since the Unix epoch.
    
    Parameters:
    
    sourceValue - value in source domain
    
    Returns:
    
    number of seconds since midnight 1 Jan 1970
  - getTimeMappers
```
public static TimeMapper[] getTimeMappers()
```
    Returns a selection of time mapper instances.

Class TimeMapper

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

TARGET_NAME

DECIMAL_YEAR

MJD

JD

UNIX_SECONDS

ISO_8601

Constructor Detail

TimeMapper

Method Detail

getTargetName

getSourceClass

getSourceName

getSourceDescription

toUnixSeconds

getTimeMappers