27:ech_plot--Run Plot Utility

Many of the temporary results arrays stored in the reduction database can be of assistance when tracking down problems during a reduction. All of these can be graphically examined using the ech_plot task/ECHMENU Option 27.

This utility prompts for object names for the Y-axis (and optionally the X-axis separated by a comma). If a null object name is returned then that axis will be automatically generated using monotonically increasing integer values.

The normal usage will be to supply only the name of the Y-axis object and leave the X-axis to be auto generated. An exception is when plotting wavelength objects along the X-axis.

Note that unless you are interested in the first order of a multi-order array then the array indices to start plotting from must be supplied.

e.g.: OBJ would denote the first orders' extracted object spectra. OBJ[1,4] would denote the fourth orders' extracted object spectra. ARC[100,13,2] would denote the region of the second arc frames thirteenth order starting at X-sample 100.

Note that in this last case unless the N(umber) of samples to plot has been set to less than the array X-dimension then some samples from the fourteenth order would also be plotted.

Also provided are the following facilities most of which are selected by typing the single character followed by carriage-return.

• B(rowse) Used in conjunction with an imaging display. The object or arc data frame should be specified or it will be prompted for (e.g.: B MYOBJ)

  ECHOMOP will display the image and then put a cursor on the display, you can then position the cursor and type a key indicating which type of data you wish to select for plotting.

  Options include:

  • O -- for object order
  • A -- for arc order
  • S -- for scrunched object order
  • F -- for flat-field model balance factors
  • S -- for sky model

  All arrays are plotted using the cursor position to determine which order, subsample etc. is required. By default the full X-axis dimension is used, unless the N command is used to explicitly set the number of samples to plot.

  For example, setting N to 20 and imaging the arc frame would allow the extracted profile of an arc line to be plotted simply by positioning the cursor on the line on the image and hitting A, plotting a 20-sample section of the extracted arc from the requisite order.

• D(irectory)/ FD (full directory)

  Lists a directory of reduction database objects. These are not all arrays and therefore not all plottable. The most common objects are listed by D(ir) and are all arrays.

  The names are such that it is easy to recognise which arrays contain the information required. For example the object FFLT contains the fitted flat-field balance factors for each order and trace offset.

  Specifying an object name without any dimensional specifications will plot the first N elements starting from the beginning of the array, i.e., ARRAY[1,1,1....] to ARRAY[N,1,1....]

• E(xit)

  Returns to the main ECHMENU menu or exits from the ech_plot single activity task.

• G(raphics/Grayscale)

  Toggles the plotting mode. The grayscale mode is useful for plotting swathes of 2-D and 3-D objects. e.g.:

  • in Graphics mode -- FSKY[1,1,1] plots the first spatial increment of the sky model for order 1.

  • in Grayscale mode -- FSKY[1,1,1] images the entire sky model for order 1. Thus in most cases the first two indices will always be equal to 1 when using grayscale plotting.

• H(elp)

  Accesses the HELP Facility.

• I(nteractive cursor)

  Sets the cursor display such that the cursor may be moved around the next graph to be plotted and the exact data values plotted can be examined (by pressing the space character).

• N(umber of samples)

  Sets the number of data samples plotted from the arrays. Unless specified in the object name, plotting always commences from the beginning of the array and the N is set to the maximum number of elements in the array. Setting a smaller value effectively allows you to zoom in on a small subsection of any array.

• L(imit setting)

  Allows the X- and Y-limits of the plot to be set. The limits are normally calculated automatically according to the data in the array. To resume auto scaling just set all the X,Y limits back to 0.

• R(ebin factor)

  Sets the degree of re-binning to be performed on the data before plotting it. It remains active until reset to 1 (indicating no rebinning). Specify a positive factor for simple summed bins, and a negative factor to request full smoothing.

• S(tyle)

  Allows the specification of various style parameters for the plots. The line styles and colours may be specified, as may the plot style. The following keywords are recognised and may be appended to the S to save time. e.g., S RED sets the plot colour to red.

  Keywords:

  • Colours RED,WHITE,BLACK,BLUE,GREEN,YELLOW,CYAN,MAGENTA
  • Line types DOTD,DASH,LINE
  • Plot types POINTS,LINES,*,+,x,BINS
  • Text fonts ROMAN,ITALIC
  • Misc PROMPT,NOPROMPT

• U(ser-defined window)

  Toggles user-windowing. When this is activated each subsequent plot will prompt the user to select two limits on the display surface. A box based on these limits will then be used for the plot.

  This allows complete freedom in producing a set of plots. Plots may be partially overlaid, stacked etc. Once you have produced the display required the easiest way to get a hardcopy of it is to use the built in facilities on your workstation/X-terminal to grab it from the screen (this normally results in a Postscript file).

• W(indowing)

  Permits the division of the plotting surface into panes into which subsequent graphs are plotted. Two factors are requested, the subdivision factor in the horizontal, and in the vertical directions. e.g., 3 and 2 would divide the surface into two rows of three graphs. Setting both factors to 1 restores normal single graph behaviour.

• + (Overplot)

  May be used either on its own or be used as a prefix to any object name. Causes the next graph to be plotted over the previous one without re-drawing the axes etc.

• ? (Help)

  The same as H(elp).

• Name of object(s) to plot

  A single object name indicates that the object array is to be plotted along the Y-axis using a default linear scale as the X-axis.

  Two object names separated by a comma indicates that the two arrays are to be plotted against each other.