Convenience functions for DS9’s (XPA) commands

Note

The full list of XPA access points can be found at: http://ds9.si.edu/doc/ref/xpa.html and XPA itself is maintained here https://github.com/ericmandel/xpa

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.window.xpa.get() or window.window.xpa.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