dither – Dither file parser

Parse or create a dither file.

Create a dither file with DitherCreator or create_dither_file().

Fake an empty dither (EmptyDither) or parse a dither file like the following (ParseDither)

# basename          modelbase           ditherx dithery seeing norm airmass
SIMDEX-obs-1_D1_046 SIMDEX-obs-1_D1_046   0.00   0.00    1.60  1.00  1.22
SIMDEX-obs-1_D2_046 SIMDEX-obs-1_D2_046   0.61   1.07    1.60  1.00  1.22
SIMDEX-obs-1_D3_046 SIMDEX-obs-1_D3_046   1.23   0.00    1.60  1.00  1.22

The create_dither_file() function is exposed via the dither_file executable

exception pyhetdex.het.dither.DitherParseError

Bases: ValueError

Custom error

exception pyhetdex.het.dither.DitherCreationError

Bases: ValueError

Raised when something fails while creating the dither file

exception pyhetdex.het.dither.DitherPositionError

Bases: RuntimeError

Fail to parse the ditherpos file

class pyhetdex.het.dither._BaseDither

Bases: object

Base class for the dither object. Just defines the common public variables

Attributes:

basename : dictionary

basenames of the dither files; key : dither; value: basename

dx, dy : dictionaries

dither relative x and y position; key : dither; value: dx, dy

seeing : dictionary

dither image quality; key dither; value : image quality

norm : dictionary

relative flux normalisation among dithers; key dither; value : normalisation

airmass : dictionary

dither airmass; key dither; value : airmass

dithers

List of dithers

absfname

Absolute file name

abspath

Absolute file path

filename

Absolute file path

class pyhetdex.het.dither.EmptyDither

Bases: pyhetdex.het.dither._BaseDither

Creates a dither object with only one entry.

The dither key is D1, basename and absfname are left empty, dx and dy are set to 0 and image quality, illumination and airmass are set to 1. It is provided as a stub dither object in case the real one does not exists.

_no_dither()

Fake a single dither

class pyhetdex.het.dither.ParseDither(dither_file)

Bases: pyhetdex.het.dither._BaseDither

Parse the dither file and store the information in dictionaries with the string Di, with i=1,2,3, as key

Parameters:

dither_file : string

file containing the dither relative position.

Raises:

DitherParseError

if the key Di is not found in the base name

_read_dither(dither_file)

Read the relative dither position

Parameters:

dither_file : string

file containing the dither relative position. If None a single dither added

class pyhetdex.het.dither.DitherCreator(fplane_file, shot, dither_positions=[['000', 0.0, -1.27, -1.27, 0.0, 0.73, -0.73]])

Bases: object

Class to create dither files

Initialize the dither file creator for this shot

Read in the locations of the dithers for each IFU from dither_positions.

Parameters:

fplane_file : str

path the focal plane file; it is parsed using FPlane

shot : pyhetdex.het.telescope.Shot instance

a shot instance that contains info on the image quality and normalization

dither_positions : list of lists, optional

list of lists with 2*n+1 elements: the first element is the id_, used in, e.g., create_dither(), then there are the n x-positions of the dithers and finally their n y-positions

Raises:

DitherPositionError

if the number of x and y dither shifts for one id does not match

Attributes:

ifu_dxs, ifu_dys : dictionaries

key: ihmpid; key: x and y shifts for the dithers

shot : pyhetdex.het.telescope.Shot instance

fplane : FPlane instance

classmethod from_file(fplane_file, shot, dither_positions_file)

Create an instance of the class reading the dither positions from a file.

Parameters:

fplane_file : str

path the focal plane file; it is parsed using FPlane

shot : pyhetdex.het.telescope.Shot instance

a shot instance that contains info on the image quality and normalization

dither_positions_file : str

path to file containing the positions of the dithers for each IHMPID; the file must have the following format:

ihmpid x1 x2 ... xn y1 y2 ... yn

_store_dither_positions(dither_positions)

Store the dither positions into the ifu_dxs and ifu_dys dictionaries

dxs(id_, idtype='ifuslot')

Returns the x shifts for the given id_

Parameters:

id_ : str

the id of the IFU

idtype : str, optional

type of the id; must be one of 'ifuid', 'ihmpid', 'specid'

Returns:

ndarray

x shifts

dys(id_, idtype='ifuslot')

Returns the y shifts for the given id_

Parameters:

id_ : str

the id of the IFU

idtype : str, optional

type of the id; must be one of 'ifuid', 'ihmpid', 'specid'

Returns:

ndarray

y shifts

create_dither(id_, basenames, modelbases, outfile, idtype='ifuid')

Create a dither file

Parameters:

id_ : str

the id of the IFU

basenames, modelnames : list of strings

the root of the file and model (distortion, fiber etc); their lengths must be the same as ifu_dxs

outfile : str

the output filename

idtype : str, optional

type of the id; must be one of 'ifuid', 'ifuslot', 'specid'

pyhetdex.het.dither.argument_parser(argv=None)

Parse the command line

pyhetdex.het.dither.create_dither_file(argv=None)

Function that creates the dither file

Parameters:

argv : list of strings

if not provided sys.argv is used

pyhetdex.het.dither.check_dithers(n_dithers, basenames, modelbases)

Check that the number of base names and model base names are either one or the number of dithers

Parameters:

n_dithers : int

number of dithers

basenames, modelbases : list of strings

list of bases for the file names

Returns:

bool

True is the check passed, False otherwise

pyhetdex.het.dither.format_names(names, n_dithers, id_)

Expand and format the names. If there is only one name, replicate it len(dxs) times, then format the names using the dither number and the id_.

Parameters:

names : list of strings

name to format

n_dithers : integer

number of dithers

Returns:

out_names : list of strings

list of length n_dithers containing formatted names

pyhetdex.het.dither.sort_basenames(basenames, extension, headerkey)

For each basenames[i]+extension extract the headerkey and sort basenames according to the key value

Parameters:

basenames : list of string

list of basenames

extension : list

add to each basename to build a file name

headerkey : string

name of the header key containing the values to use for sorting

Returns:

sorted_basenames : list of strings

basenames sorted according to the value of headerkey