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Python: Documented moon quarter type and functions.

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Don Cross
2019-07-17 20:17:04 -04:00
parent 8287a211a9
commit 3ad7c7d9ec
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71
source/python/README.md
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@@ -138,6 +138,29 @@ a celestial body crossing a certain hour angle as seen by a specified topocentri
---
<a name="MoonQuarter"></a>
### class MoonQuarter
**A lunar quarter event along with its date and time.**
An object of this type represents one of the four major
lunar phases that appear on calendars:
new moon, first quarter, full moon, or third quarter.
Along with the `quarter` attribute that specifies the
type of quarter, it contains a `time` field that indicates
when the lunar quarter event happens.
| Type | Attribute | Description |
| --- | --- | --- |
| `int` | `quarter` | 0=new moon, 1=first quarter, 2=full moon, 3=third quarter. |
| [`Time`](#Time) | `time` | The date and time of the lunar quarter. |
---
<a name="Observer"></a>
@@ -787,6 +810,29 @@ Certain values of the angle have conventional definitions:
---
<a name="NextMoonQuarter"></a>
### NextMoonQuarter(mq)
**Continues searching for lunar quarters from a previous search.**
After calling #Astronomy_SearchMoonQuarter, this function can be called
one or more times to continue finding consecutive lunar quarters.
This function finds the next consecutive moon quarter event after
the one passed in as the parameter `mq`.
| Type | Parameter | Description |
| --- | --- | --- |
| [`MoonQuarter`](#MoonQuarter) | `mq` | A value returned by a prior call to #SearchMoonQuarter or #NextMoonQuarter. |
### Returns: #MoonQuarter
---
<a name="Search"></a>
@@ -915,6 +961,31 @@ This function is useful for finding general phase angles outside those four quar
---
<a name="SearchMoonQuarter"></a>
### SearchMoonQuarter(startTime)
**Finds the first lunar quarter after the specified date and time.**
A lunar quarter is one of the following four lunar phase events:
new moon, first quarter, full moon, third quarter.
This function finds the lunar quarter that happens soonest
after the specified date and time.
To continue iterating through consecutive lunar quarters, call this function once,
followed by calls to #NextMoonQuarter as many times as desired.
| Type | Parameter | Description |
| --- | --- | --- |
| [`Time`](#Time) | `startTime` | The date and time at which to start the search. |
### Returns: #MoonQuarter
---
<a name="SearchRelativeLongitude"></a>

51
source/python/astronomy.py
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@@ -4084,11 +4084,46 @@ def SearchMoonPhase(targetLon, startTime, limitDays):
return Search(_moon_offset, targetLon, t1, t2, 1.0)
class MoonQuarter:
"""A lunar quarter event along with its date and time.
An object of this type represents one of the four major
lunar phases that appear on calendars:
new moon, first quarter, full moon, or third quarter.
Along with the `quarter` attribute that specifies the
type of quarter, it contains a `time` field that indicates
when the lunar quarter event happens.
Attributes
----------
quarter : int
0=new moon, 1=first quarter, 2=full moon, 3=third quarter.
time : Time
The date and time of the lunar quarter.
"""
def __init__(self, quarter, time):
self.quarter = quarter
self.time = time
def SearchMoonQuarter(startTime):
"""Finds the first lunar quarter after the specified date and time.
A lunar quarter is one of the following four lunar phase events:
new moon, first quarter, full moon, third quarter.
This function finds the lunar quarter that happens soonest
after the specified date and time.
To continue iterating through consecutive lunar quarters, call this function once,
followed by calls to #NextMoonQuarter as many times as desired.
Parameters
----------
startTime : Time
The date and time at which to start the search.
Returns
-------
#MoonQuarter
"""
angle = MoonPhase(startTime)
quarter = int(1 + math.floor(angle / 90.0)) % 4
time = SearchMoonPhase(90.0 * quarter, startTime, 10.0)
@@ -4098,6 +4133,22 @@ def SearchMoonQuarter(startTime):
return MoonQuarter(quarter, time)
def NextMoonQuarter(mq):
"""Continues searching for lunar quarters from a previous search.
After calling #Astronomy_SearchMoonQuarter, this function can be called
one or more times to continue finding consecutive lunar quarters.
This function finds the next consecutive moon quarter event after
the one passed in as the parameter `mq`.
Parameters
----------
mq : MoonQuarter
A value returned by a prior call to #SearchMoonQuarter or #NextMoonQuarter.
Returns
-------
#MoonQuarter
"""
# Skip 6 days past the previous found moon quarter to find the next one.
# This is less than the minimum possible increment.
# So far I have seen the interval well contained by the range (6.5, 8.3) days.