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Directory Listing of Routines


Routine Descriptions

DAS2DECODER__DEFINE[1]

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 Convert a byte array to an array of given type

 :Private:

 :Params:
    aPktData : in, required, type=byte array
       The binary data for an entire das2 packet
 :Keywords:
    debug : in, optional, hidden, type=bool
       If !true print debugging info to standard error

 :Returns:
    an array of given type, time values are converted to TT2000
 
 :History:
    Jul. 2018, D. Pisa : original
    May  2019, C. Piker : updates to auto-convert times to TT2000

(See external/das2pro/src/das2decoder__define.pro)


DAS2DECODER__DEFINE[2]

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 Initialize a das2 stream data value decoder.  Handles coversion of 
 time values to TT2000.

 :Private:

 TODO: This should be in das2_parsestream.pro since it uses packet 
       headers.

 :Param:
    hPlane : in, required, type=hash
        A hash as return by xml_parse for the <x>, <y>, <z> or <yscan> plane
        of interest.
    

(See external/das2pro/src/das2decoder__define.pro)


DAS2DECODER__DEFINE[2]

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 Return the total number of bytes converted to data values in each
 invocation of das2decoder::decode.

 :Private:

(See external/das2pro/src/das2decoder__define.pro)


DAS2DECODER__DEFINE[3]

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 Data plane decoder object, plain object, does not derive from
 IDL_Object, can't have auto properties

 :Private:

(See external/das2pro/src/das2decoder__define.pro)


DAS2DIM__DEFINE

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 Das2 dimension object, provides arrays and properties for a single
 physical dimension, such as Time or Spectral Density

(See external/das2pro/src/das2dim__define.pro)


DAS2DS__DEFINE[1]

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 Answers the question, how big are data packets for this dataset.

 Datasets can be parsed from das2 streams.  A stream consists of 
 header and data packets.  Each data packet must have a sufficent 
 number of data values to increment the highest index of the internal
 data arrays by 1.

 :Returns:
    The number of total bytes in each data packet for this dataset.
     

(See external/das2pro/src/das2ds__define.pro)


DAS2DS__DEFINE[2]

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 Inspect all owned variables and get the index range of the
 overall dataset.  Map sizes to array dimensions using the 
 index maps.

 :Private:

(See external/das2pro/src/das2ds__define.pro)


DAS2DS__DEFINE[2]

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 Provide the key names for all physical dimensions in the dataset

 :Keywords:
     D : in, type=boolean, optional
        Return just the string ids for the data dimensions

     C : in, type=boolean, optional
        Return just the string ids for the coordinate dimensions

 :Returns:
    list - A list of strings containing the hask keys for the requested
        physical dimensions.

 :Author:
    Chris Piker

(See external/das2pro/src/das2ds__define.pro)


DAS2DS__DEFINE[3]

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 Dataset objects (das2ds) explicitly denote, and separate, array index
 dimensions and physical dimensions.

 For each physical space, such as Time or Spectral Density, there is a das2dim
 (das2 dimension) member object of a dataset.  Each dimension may have more
 than one set of applicable values.  For example in the Time dimension there
 may be a set of values that represent when a measurement was taken in UTC 
 and, the time uncertianty in seconds.  Each set of measurements and thier
 units are contained within a das2var (das2 variable) object.

 To make plots and analyze data we have to know which values "go together".
 Considering an energy spectra dataset for a moment, we would need to know
 what array index numbers should be used to match a time, with an energy level
 with a count rate, with a look direction.  This is a bookkeeping problem.
 We could solve this problem in a manner similar to the ISTP standard by
 insisting that each dimension of an array correspond with a single physical
 dimension.  Doing so quickly results in display tools confusing index space
 for physical space, a problem that we want to avoid.  Instead, to provide this
 information, an overall dataset index space is defined.  Each variable within
 the dataset provides a mapping between it's array indices and the overall 
 dataset index space.  This mapping can be used to correlate values from
 various arrays without constraining the nature of the physical measurements
 contained within the dataset.

 :Author:
    Chris Piker

(See external/das2pro/src/das2ds__define.pro)


DAS2PROP__DEFINE

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 Das2 property has a type and value

(See external/das2pro/src/das2prop__define.pro)


DAS2VAR__DEFINE[1]

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 Provide index ranges for this variable in terms of the top level dataset
 index space.

 Cordinate variables often have lower dimensional arrays than the data
 variables.  For example, think of an insturment that collects energetic
 partical hit-counts in 45 energy bands once per minute.  The coordinates of 
 this dataset would be energy and time, with the data being the count rate.
 An hour's worth of these measurements could be stored in the following
 arrays:
 
 ```
    aTime    = long64arr(60)
    aEnergy  = fltarr(45)
    aCounts  = intarr(45, 60)
 ```

 Looking at the index ranges for this simple dataeset it's apparent that the
 first index of array aTime must correspond to the second index of array 
 aCounts.  To help visualize this mapping, especially when datasets become
 more complex, we could "line-up" all the index ranges to make the mapping
 more explicit:

 ```
 Values   Extents
 ------   -------
 Time     [ - , 60]
 Energy   [ 45, - ]
 Counts   [ 45, 60]
 ```

 This is what the idxmap function outputs, the mapping of index space of a
 single array to the overall dataset index space.  Assume now that these
 arrays are actually the `.values` member of three different das2var objects.
 Calling `.dshape()` would yield the following (without comments of course):

 ```
 print, vTime.dshape() 
   -1      0      ; var is degenerate in first dataset index (0 values)
    0     60      ; second dataset index maps to first var index (60 values)

 print, vEnergy.dshape()
    0     45      ; first dataset index maps to first var index (45 values)
   -1      0      ; var is degenerate in the second dataset index (0 values)

 print, vCounts.dshape()
    0     45      ; first dataset index maps to first var index (45 values)
    1     60      ; second dataset index maps to second var index (60 values)
 ```

 :Returns:
   A 2 by N array, where N is the number of independent indexes required to
   correlate all values in a dataset.

 :Author: Chris Piker

(See external/das2pro/src/das2var__define.pro)


DAS2VAR__DEFINE[2]

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 Provide access to the underlying value using standard array indexing.

 Due to limitations of the IDL language (i.e. array._overloadBracketsRightSide
 doesn't exist) ranges are only supported up to 3 index dimensions.  To
 get a block range for arrays larger than rank 3 use the .array() method to
 get the array variable directly.

 To avoid suprise return values when gathing a slice of data, the indexmap
 is ignore.  If you are getting single values (not recommended in IDL) and
 wish to work in dataset index space use the .at() method.

(See external/das2pro/src/das2var__define.pro)


DAS2VAR__DEFINE[2]

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 Das2 Variable, an array, it's units and it's index map.

(See external/das2pro/src/das2var__define.pro)


DAS2_DOUBLE_TO_TT2000

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 Description: Convert a double represeting a binary das2 time value to tt2000

 tt2000 is the number of nano-seconds since 2000-01-01T11:58:55.816

 :Params:
    timeunits: in, required
      This is one of the strings 'us2000', 'mj1958', 't2000' or 't1970'
    value: a DOUBLE value

 To read UTC time strings in a variety of formats use das2_text_to_tt2000
 instead of this function.

 To avoid leap seconds, epoch time is first converted to a calendar
 representation and the broken down calendar time is converted to TT2000
 using the built-in CDF_TT2000 proceedure

(See external/das2pro/src/das2_double_to_tt2000.pro)


DAS2_PARSESTREAM[10]

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 Parse the contents of a byte buffer into a list of das2 dataset (das2ds) 
 objects.  This is an all-at-once parser that can't handle datasets larger
 than around 1/2 to 1/3 of the host machine's ram. 

 :Returns:
    list - a list of das2 dataset (das2ds) objects.

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[1]

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 Try to determine a decent name for a dimension given a units string,
 return !null if nothing works

 :Private:

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[2]

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 Inspect the properties sub item of a stream header object hash and
 pull out the requested property value, if present.

 :Private:

 :Params:
    hObj : in, required, type=hash
        A hash, as returned by xml_parse() of the <stream>, <x>, <y>, <z>,
        <yscan> element in question.
    sProp: in, required, type=string
        The property to find

 :Returns:
    !null if the property is not present or a type object
    (int, String, datum, datum range, etc.)

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[2]

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 Make a new variable given a plane header

 :Private:

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[3]

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 Given a stream header, a plane header and a plane type, 
 make a new physical dimension structure

 :Private:

 :Returns:
    The new dimension

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[4]

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 When multiple planes of the same type are present in the stream it's possible
 that they are related

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[5]

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 Add dimenions and variables from a single type of plane to a dataset

 :Private:

 :Params:
    hStream : in, required, type=hash

    hPkt  : in, required, type=hash

    sPlaneType : in, required, type=string
       The plane tag, one of x,y,z,yscan depending on which type of
       planes to find

    sDatAxis : in, required, type=string
       The axis for data from this plane, which is not necessarily
       the plane tag.  For examply yscan data can be either y values
       (waveform) or z values (spectra)

    idxmap : in, required, type=intarr
       How values from this dat array map to overall dataset indices
       since IDL is backwards from everyone else these are easy to 
       mix up. 

    iOffest : in, required, type=int
       The offset into the packet header for data that has 
       already been claimed by other dimensions.  Depends on all
       <x><x>... coming before all <y><y>... before all <z><z>... 
       before all <yscan><yscan>... in the packet definition.
       
       No way to check this currently since we are using xml_parse()
       from IDL that does not preserve this information.

   dataset : in, required, type=das2ds
       The dataset object to receive these new dimensions

 :Keywords:
    FIRST : out, optional, type=das2dim
       Used to save off the first dimension of a type.

 :Returns:
    The new offset into the records for the start of data from other
    dimension sets.

unction _das2_addDimsFromHdr, $
hStream, hPkt, sPlaneType, sDatAxis, idxmap, iOffset, sKind, $
dataset, FIRST=dimFirst

compile_opt idl2, hidden
	
sUnitAttr = '%units'
if sPlaneType eq 'yscan' then begin 
	sUnitAttr = '%zUnits'
endif

bXOffset = !false
if hStream.haskey('properties') then begin
	h = hStream['properties']
	if h.haskey('%renderer') then bXOffset = (h['%renderer'] eq 'waveform')
	if h.haskey('%String:renderer') then bXOffset = (h['%String:renderer'] eq 'waveform')
endif

if ~(hPkt.haskey(sPlaneType)) then return, iOffset

; make sure planes are always a list
lPlanes = hPkt[sPlaneType]
if typename(lPlanes) ne 'LIST' then lPlanes = list( hPkt[sPlaneType] )
			
; make decoders, variables and dimensions for each plane
for iPlane=0, n_elements(lPlanes) - 1 do begin
					
	hPlane = lPlanes[iPlane]

	decoder = obj_new('das2decoder', iOffset, hPlane)
	iOffset += decoder.chunkSize()
	var = _das2_varFromHdr( hPlane, idxmap, decoder)
		
	; Add to an existing dimension (if min/max) or start a new one.
	
	; When we restructure das2 streams, dimensions (or some other plane
	; grouping mechanism) need to be added
		
	propSrc = _das2_getProp(hPlane, 'source')
	propOp  = _das2_getProp(hPlane, 'operation')
	
	; get an existing dim...
	dim = !null
	if propSrc ne !null then begin
		if dataset.dims.haskey(propSrc.value) then $
			dim = dataset.dims[propSrc.value]
	endif
	
	; ...or create a new one
	if dim eq !null then begin
		
		;printf, -2, sDatAxis, sKind, hPlane
		
		dim = _das2_dimFromHdr(hStream, sDatAxis, hPlane, sKind)
		
		if (sPlaneType eq 'x') && bXOffset && (dimFirst eq !null) then $
			dim.vars['reference'] = var $
		else $
			dim.vars['center'] = var
		
		; determining good names for dimensions is not easy...
		sName = !null
		if sSrc ne !null then sName = sSrc
		
		if sName eq !null then begin
			if hPlane.haskey('%name') then sName = hPlane['%name']
		endif
		if sName eq !null then begin
			if hPlane.haskey(sUnitAttr) then sName = _das2_nameFromUnits(hPlane[sUnitAttr])
		endif
		if sName eq !null then sName = string(sPlaneType, iPlane, format='%s_%d')
		
		if dataset.dims.haskey(sName) then $
			message, 'Error in das2 stream, name '+sName+' repeats in the same packet"
		
		dataset.dims[sName] = dim
		
		;printf, -2, dataset
		
		; Set the name based on the first plane of each kind.
		; WARNING ASSUMES: _das2_addDimsFromHdr is called in order from
		;                  <x> ... to <yscan>  This is not the best 
		; idea in the world, but the das2.2 stream format has no concept of
		; a dataset name.
		if dimFirst eq !null then dataset.name = sName
								
	endif else begin
		message, 'Peaks-averages datasets such as Voyager SA are not yet supported'
		sRole = _das2_op2role(propOp)
		dim.vars[sRole] = var
	endelse
		
	; Save off the first <x><y><z><yscan> dim in case we need to add an offset
	; variable to it from the ytags
	if dimFirst eq !null then begin
		dimFirst = dim
	endif
	
endfor

return, iOffset
nd

 --------------------------------------------------------------------------- ;
+
 Make a new dataset object given stream and packet headers. 

 :Private:

 :Params:
    hStrmHdr: in, required, type=hash
       The parsed stream XML header as returned from xml_parse

    hPktHdr: in, required, type=hash
       The parsed packet XML header as returned from xml_parse

 :Keywords:
    DEBUG: in, optional, private, type=bool
       If true print debugging information

 :Author:
    Chris Piker (hence the snark)

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[6]

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 Parse data for a single packet using the given dataset structure and append
 it to the variable arrays

 note: since das2 streams don't put a length on the data packets there's
       no way to cross check that the stream definition matches the length
       of the data.  All we can do is try to parse it without running of
       the end

 :Private:

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[7]

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 Convert all the variable value lists to arrays

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[8]

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 Look to see if a message was an exception, if it was, format it as
 a string and return it.

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSESTREAM[9]

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 Create a dataset structure from a list of packets.

 :Private:

 :Params:
    pkts : in, required, type=byte array
       A byte vector containing all the packets in a das2 stream, the
       header packet (id [00]) should not be included.

 :Returns:
    list of dataset structures

 :History:
     Jul. 2018, D. Pisa : original 
     Nov. 2018, D. Pisa : fixed object.struct conversion for ypackets
     May  2018, C. Piker : refactored

(See external/das2pro/src/das2_parsestream.pro)


DAS2_PARSETIME

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 Given a string, parse typical delimited ASCII date/time and
 return year, month, day of month, day of year, hour, minute, second.

 This function loads JULDAY and CALDAT as dependencies and prints error or
 debug messages to stderr.

 :Params:
   timestr: in, required, type=string
	    Either 4-digit or 2-digit years can be parsed.  4-digit years must be in 
      the range range 1900 through 2199, and 2-digit years are only allowed in
      the range 1960 through 2059.

   year: out, required, type=integer
      Year like 2000

	 month: out, required, type=integer
      Month of year (1 through 12)

   day: out, required, type=integer
      Day of month (1 through 31)

   doy: out, required, type=integer
      Day of year (1 through 366)

   hour: out, required, type=integer
      Hour of day (0 through 23)

   minute: out, required, type=integer
      Minute of hour (0 through 59)

   second: out, required, type=double
      Second of minute (0.0d0 to 61.0d0)

 :Keywords:
    julian: out, optional, type=double
       Double precision fractional Julian Day

    debug: in, optional, type=bool
       Turn on certian debug output strings

 :Returns:
    integer: 0 on success, 1 on failure

 :Examples:
     status = das2_parsetime (timestr, year, month, day_month, day_year $
              [, hour, minute, second] [, julian=julian] [, /debug])

 :History:
	2012-10-30, L. Granroth: Rewrite using regex
	2019-05-23, L. Granroth: Extended to handle nanoseconds

(See external/das2pro/src/das2_parsetime.pro)


DAS2_READHTTP[1]

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 Provide feedback that the stream is downloading

 :Private:

(See external/das2pro/src/das2_readhttp.pro)


DAS2_READHTTP[2]

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 Request data from a specific das2 server using native HTTP GET parameters
 
 :Params:
    sUrl:  in, required, type=string
       The full HTTP GET url to retrieve, it doesn't need to be URL encoded
       this function will handle that step

 :Keywords:
    params: in, optional, type=list
    ascii: in, optional, type=boolean
    extras: in, optional, type=list
    verbose: in, optional, type=boolean

 :Returns:
    A list of dataset objects.  Each dataset object corresponds to a single
    packet type in the input.  If no datasets could be retrieved the function
    return an empty list, so ret_val.length = 0.

 :Requires:
    xml_parse: IDL 8.6.1
    IDLnetURL: IDL 6.4

 :Example:
    sServer = 'http://planet.physics.uiowa.edu/das/das2Server'
    sDataset = 'Cassini/RPWS/HiRes_MidFreq_Waveform'
    sBeg = '2008-08-10T09:06'
    sEnd = '2008-08-10T09:13'
    sParams = '10khz'
    sFmt = '%s?server=dataset&dataset=%s&start_time=%s&end_time=%s&params=%s'
    sUrl = string(sServer, sDataset, sMin, sMax, sParams, format=sFmt)
   
    lDs = das2_readhttp(sUrl, /messages=sMsg)

    if lDs eq !null then begin
       print, sMsg
       stop
    endif

    print, n_elements(lDs), /format="%d datesets read"

    print, lDs[0]

 :History:
    Jul. 2018, D. Pisa : original
    May  2019, C. Piker: refactored

(See external/das2pro/src/das2_readhttp.pro)


DAS2_TEXT_TO_TT2000

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 Description: Convert a string time value to a cdf_tt2000 epoch time

 tt2000 is the number of nano-seconds since 2000-01-01T11:58:55.816

 :Params:
    sTime: in, required
      This is a string time value such as '2007-001T14:00'
 
 This function works by calling das2_parsetime to parse time components
 from a variety of string formats, and then calling cdf_tt2000 to get
 the epoch.

 2019-01-24 L. Granroth, original
 2019-05-23 C. Piker,    nano second accuracy fix

(See external/das2pro/src/das2_text_to_tt2000.pro)