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# Convenience functions for some of the available XPA commands

Note

The full list of XPA access points can be found at: http://ds9.si.edu/doc/ref/xpa.html

If there is no convenience function for an access point that you would like to use, you can still call it using the imexam hooks into the xpa GET and SET functions. They are aliased to your object (for example “window”) as window.get() or window.set()

alignwcs(on=True):
  align loaded images by wcs,
blink(blink=None,interval=None):
  blink frames
clear_contour():
  clear contours from the screen
cmap(color=None,load=None,invert=False,save=False, filename=’colormap.ds9’):

  set the color map of the current frame The available maps are “heat”,”grey”,”cool”,”aips0”,”a”,”b”,”bb”,”he”,”i8”

  color: string
    color must be set to one of the available DS9 color map names
  load: string, optional
    set to the filename which is a valid colormap lookup table valid contrast values are from 0 to 10, and valid bias values are from 0 to 1
  invert: bool, optional
    invert the colormap
  save: bool, optional
    save the current colormap as a file
  filename: string, optional
    the name of the file to save the colormap to
colorbar(on=True):
  turn the colorbar at the bottom of the screen on and off
contour(on=True, construct=True):

  on: Set to true to turn on contours

  construct: optional
    Will open the contour dialog box which has more options
contour_load(filename):
  load contours into the window from the specified filename
crosshair(x=none,y=none,coordsys=”physical”,skyframe=”wcs”,skyformat=”fk5”,match=False,lock=False):

  control the current position of the crosshair in the current frame, crosshair mode is turned on

  x: string or int
    The value of x is converted to a string for the call to XPA, use a value here appropriate for the skyformat you choose
  y: string or int
    The value of y is converted to a string for the call to XPA, use a value here appropriate for the skyformat you choose
  coordsys: string, optional
    The coordinate system your x and y are defined in
  skyframe: string, optional
    If skyframe has “wcs” in it then skyformat is also sent to the XPA
  skyformat: string, optional
    Used with skyframe, specifies the format of the coordinate which were given in x and y
  match: bool, optional
    If set to True, then the wcs is matched for the frames
  lock: bool, optional
    If set to True, then the frame is locked in wcs
cursor(x=None,y=None):
  move the cursor in the current frame to the specified image pixel, it will also move selected regions
disp_header():
  display the current header using the ds9 header display window
frame(n=None):

  convenience function to switch frames or load a new frame (if that number does not already exist)

  n: int, string, optional
    The frame number to open or change to. If the number specified doesn’t exist, a new frame will be opened If nothing is specified, then the current frame number will be returned. The value of n is converted to a string before passing to the XPA

  frame(1) sets the current frame to 1 frame(“last”) set the current frame to the last frame frame() returns the number of the current frame frame(“new”) opens a new frame frame(3) opens frame 3 if it doesn’t exist already, otherwise goes to frame 3

get_header():
  return the header of the current extension as a string, or None if there’s a problem
grid(on=True, param=False):
  turn the grid on and off if param is True, then a diaglog is opened for the grid parameters
hideme():
  lower the ds9 window on your display
load_fits(fname=None, extname=1, extver=’SCI’):

  load a fits image to the current frame. You provide just the name, or either of the extname or extver, or you can specify the extension with the filename string. For example:

  > load_fits(‘something.fits’,extver=’SCI’) will load the SCI,1 extension

  > load_fits(‘something.fits[SCI,1]’) will load the SCI,1 extension

  > load_fits(‘something.fits’) will load the main data extension; the only data information in the case of simple fits, or the first extension in the case of a multiextension file

load_region(filename):
  load the specified DS9 formatted region filename
load_rgb(red, green, blue,scale=False, lockwcs=False):

  load 3 images into an RGBimage frame, the parameters are:

      red: string, The name of the fits file which will be loaded into the red channel

      green: string, The name of the fits file which will be loaded into the green channel

      blue: string, The name of the fits file which will be loaded into the blue channel

      scale: bool, If True, then each image will be scale with zscale() after loading

      lockwcs: bool, If True, then the image positions will be locked to each other using the WCS information in their headers

load_mef_as_cube(filename=None):
  Load a Mult-Extension-Fits image into one frame as an image cube in the image viewer
load_mef_as_multi(filename=None):
  Load a Mult-Extension-Fits image into multiple frames in the image viewer
match(coordsys=”physical”,frame=False,crop=False,fslice=False,scale=False,bin=False,colorbar=False,smooth=False,crosshair=False):

  match all other frames to the current frame using the specified option. You can only choose one of the options at a time, so set frame=False and something else in addition to your choice if you don’t want the default option.

  coordsys: string, optional
    The coordinate system to use
  frame: bool, optional
    Match all other frames to the current frame, using the set coordsys
  crop: bool, optional
    Set the current image display area, using the set coordsys
  fslice: bool, optional
    Match current slice in all frames
  scale: bool, optional
    Match to the current scale for all frames
  bin: bool, optional
    Match to the current binning for all frames
  colorbar: bool, optional
    Match to the current colorbar for all frames
  smooth: bool, optional
    Match to the current smoothing for all frames
  crosshair: bool, optional
    Match the crosshair in all frames, using the current coordsys
nancolor(color=”red”):
  set the not-a-number color, default is red
panto_image(x, y)
  convenience function to change to x,y images coordinates using ra,dec
panto_wcs(x, y,system=’fk5’):

  pan to the wcs coordinates in the image using the specified system

  x: string
    The x location to move to, specified using the given system
  y: string
    The y location to move to
  system: string
    The reference system that x and y were specified in, they should be understood by DS9
rotate(value, to=False):
  value: float [degrees]
    Rotate the current frame {value} degrees If value is 0, then the current rotation is printed
  to: bool
    Rotate the current frame to the specified value instead
save_header(filename=None):
  save the header of the current image to a file
save_rgb(filename=None):
  save an rgbimage frame as an MEF fits file
save_regions(filename=None):

  Save the regions in the current window to a DS9 style regions file

  filename: string

    The nameof th file to which the regions displayed in the current window are saved If no filename is provided then it will try and save the regions to the name of the file in the current display with _regions.txt appended

    If a file of that name already exists on disk it will no attempt to overwrite it

scale(scale=’zscale’):

  Scale the image on display. The default zscale is the most widely used option:

      Syntax

      scales available: [linear|log|pow|sqrt|squared|asinh|sinh|histequ]

      [log exp <value>]
      [datasec yes|no]
      [limits <minvalue> <maxvalue>]
      [mode minmax|<value>|zscale|zmax]
      [scope local|global]
      [match]
      [lock [yes|no]]
      [open|close]

set_region(region_string):
  display a region using the specifications in region_string example: set_region(“physical; ruler 200 300 200 400”)
showme():
  raise the ds9 display window
showpix():
  display the pixel value table
snapsave(filename,format=None,resolution=100):

  create a snap shot of the current window and save in specified format. If no format is specified the filename extension is used

  > filename: str, optioan
  >   filename of output image, the extension in the filename can also be used to specify the format If no filename is specified, then the filename will be constructed from the name of the currently displayed image with _snap.jpg appended.
  > format: str, optional
  >   available formats are fits, eps, gif, tiff, jpeg, png If no format is specified the filename extension is used
  > resolution: int, optional
  >   1 to 100, for jpeg images

zoom(par=”to fit”):
  par: string
    it can be a number (ranging 0.1 to 8), and successive calls continue zooming in the same direction it can be two numbers ‘4 2’, which specify zoom on different axis if can be to a specific value ‘to 8’ or ‘to fit’, “to fit” is the default it can be ‘open’ to open the dialog box it can be ‘close’ to close the dialog box (only valid if the box is already open)
zoomtofit():
  zoom to the best fit for the display window

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