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AHELP for CIAO 4.11 ChIPS v1

add_curve

Context: curves

Synopsis

Creates a curve (a set of two-dimensional points optionally marked by points or connected by lines)

Syntax

add_curve([id,] filename [, transform [, attributes]])
add_curve([id,] TABLECrate [, transform [, attributes]])
add_curve([id,] x, y [, transform [, attributes]])
add_curve([id,] x, y, error_list|None [, transform [, attributes]])
add_curve([id,] x, y, error_list|None, limits_list|None [, transform [,
attributes]])

Description

The function arguments.

Argument	Description
id	A ChipsId structure identifying the item.
filename	The name of the file containing the columns to display. This can include CIAO DataModel filters, such as "evt2.fits[energy=500:7000][cols sky]", to automatically filter the table before displaying it.
TABLECrate	A table crate, returned either by a read_file call or a call to the TABLECrate constructor (see "ahelp crate").
x, y	One dimensional NumPy arrays or Python lists which have the same number of elements.
error_list	An optional list of up to four error arrays (which take the same form as used for the x and y arguments). If there is a single array, or a list with one element then, then this refers to symmetrical y errors. If the list contains two elements, these are taken to be the ydown and yup error values. Three elements is ydown, yup, and xdown errors, with four elements being ydown, yup, xdown, and xup errors. The error values are relative and should be positive (even for the x/ydown values).
limits_list	An optional list of upper and/or lower limits. The list may be empty, y limits, or y and x limits.
transform	A pytransform object that determines the mapping between the logical coordinate system, where (1,1) refers to the center of the bottom-left pixel, and the display system. At present this should either be a LINEAR2DTransform or WCSTransform object that contains a tangent-plane projection.
attributes	Configure object properties by giving an attribute string (a space-separated list of key=value pairs), list, dictionary, or a ChIPS object.

The add_curve command creates a curve whose attributes are specified by user preferences or in an attribute list. The new curve becomes current by default; providing a ChipsId overrides the currency state. A curve needs a minimum of a pair of numeric data arrays of the same length to plot.

If an existing plot is current, the curve is added to that plot. If there is no current plot, one is created and the curve is placed in it. To overplot curves, simply add them all to the same plot.

Up to six additional data columns may be provided as error and limits information. The error and limits information is interpreted based on how many columns are supplied to the command, as described above. On account of this, an entry for the error_list array must be provided in order to include limits data. If no error_list is needed, the value "None" may be used.

Customizing the Curve

There are several attributes that control the curve characteristics. The attributes can be set to the ChIPS defaults, values provided in the add_curve command, or values from the user's preference file.

The attributes may also be modified with the set_curve command at any time; see "ahelp set_curve" and "ahelp setget" for more information.

Please see the "Curve Preferences and Attributes" section below the examples for a list of the curve preferences.

Examples

Example 1

chips> add_curve("lc.fits[cols time, count_rate]")

Plot the time versus count_rate columns from the FITS file "lc.fits". The Data Model virtual filter syntax "[cols time, count_rate]" is used to select the X and Y columns from the file.

Example 2

chips> add_curve("lc.fits[cols time, count_rate]", ["line.color","red"])

Plot the time versus count_rate columns from the FITS file "lc.fits", and draw the lines between the points in red.

Example 3

chips> !cat src.dat
23.4 42.3
12.9 87.2
48.8 63.2
109.4 -2.3
chips> clear()
chips> add_curve("src.dat", ['line.style', 'noline'])

Here we plot up the only two columns in the ASCII file src.dat as points.

Example 4

chips> x = np.arange(11)
chips> add_curve(x, x*x)

Plot the curve y = x^2 for the integer values 0 to 10.

Example 5

chips> add_curve("lc.fits[cols time, count_rate, stat_err]")

Plot the time versus count_rate columns, and use the stat_err column as symmetric Y errors.

Example 6

chips> add_curve("lc.fits[cols time, count_rate,
stat_err]",["line.color", "red", "err.color", "coral", "symbol.style",
"circle", "symbol.size", 6])

Repeat the previous example, this time overriding several of the preference settings for curves.

Example 7

chips> dat = read_file("lc.fits[cols time, rate, error]")
chips> add_curve(dat)

Read in the time, rate, and error columns from a file using the Crates routine read_file, then plot the data.

Example 8

chips> z = np.arange(10)
chips> add_curve(z, z-4, z*0.15)

Create a curve with symetric Y error bars (15% of the value). To plot asymetric bars, try:

chips> add_curve(z, z-4, [z*0.2, z*0.1])

Example 9

chips> x = np.arange(0,10,0.1)
chips> set_preference("curve.symbol.style", "none")
chips> add_curve(x, np.sin(x), ["line.color", "plum"])
chips> add_curve(x, np.cos(x), ["line.color", 0xf04539, "line.style",
"dot"])

Set the symbol.style preference to "none" before adding the curves. Overplot the cosine curve on top of the sine curve, specifying attributes in a list.

Example 10

chips> cr = read_file("data.fits")
chips> x = get_colvals(cr, "X")
chips> y = get_colvals(cr, "Y")
chips> add_curve(x, y)
chips> vals = ChipsCurve()
chips> vals.line.style = "none"
chips> vals.symbol.fill = False
chips> vals.symbol.size = 5
chips> vals.symbol.color = "sienna"
chips> set_curve(vals)

Create a curve of the X and Y columns from data.fits. Populate the "vals" structure, then set the curve attributes.

Example 11

chips> add_image("img.fits")
chips> cr = read_file("fov1.fits[ccd_id=3]")
chips> x = copy_colvals(cr, "x")
chips> y = copy_colvals(cr, "y")
chips> tr = get_transform(cr, "EQPOS")
chips> add_curve(x, y, tr, ["symbol.style", "none"])

Here we overplot the polygon from a Chandra Field-Of-View file (fov1.fits), representing the edges of ACIS-I3, onto an image. We here take advantage of the transform support and read in the SKY column for the polygon (namely X and Y) and the transform data needed to convert this into the (Ra,Dec) system used to display the image. An alternative would have been to say

chips> ra = copy_colvals(cr, "ra")
chips> dec = copy_colvals(cr, "dec")
chips> add_curve(ra, dec, ['symbol.style', 'none', 'line.color', 'red'])

and use the virtual columns RA and Dec from the FOV file directly.

Curve Preferences and Attributes

The attributes associated with curves are given in the following table, where the "Set?" column refers to whether the attribute can be changed using the set_curve() command. To change the curve preference settings prepend "curve." to the attribute name.

Attribute	Description	Options	Default	Set?
baddata	How to handle NaNs and +/-infs in data	omit, ignore: omit means to discard bad data point and leave gap, ignore means discard bad points, connecting the surrounding points	omit	Yes
depth	Depth of the curve	see the Depth section of "ahelp chipsopt"	default	Yes
err.caplength	Length of the cap drawn on error bars (when err.style is cap).	1 to 100, inclusive.	10	Yes
err.color	Color of the curve err bars	name or hex; see the Color section of "ahelp chipsopt"	default	Yes
err.down	Plot y down errors if data provided	see the Booleans section of "ahelp chipsopt"	true	Yes
err.left	Plot x down errors if data provided	see the Booleans section of "ahelp chipsopt"	true	Yes
err.right	Plot x up errors if data provided	see the Booleans section of "ahelp chipsopt"	true	Yes
err.style	Specifies the error bar style	bar\|line\|cap (bar and line are identical)	line	Yes
err.thickness	Specifies the thickness of error bars	0.5 to 10.0; see the Thickness section of "ahelp chipsopt"	1	Yes
err.up	Plot y up errors if data provided	see the Booleans section of "ahelp chipsopt"	true	Yes
limitlength	Length of the bars for upper and lower limits	0 to 1 in plot normalized coordinates	0.05	Yes
limitoverride	Should both the limit and the error bar be drawn on a point?	true = hide the errors, false = show the errors; see the Booleans section of "ahelp chipsopt"	true	Yes
line.color	Color of the curve line	name or hex; see the Color section of "ahelp chipsopt"	default	Yes
line.style	the pattern used for the curve line style	see the Line Style section of "ahelp chipsopt"	solid	Yes
line.thickness	Thickness of the curve line	0.5 to 10.0; see the Thickness section of "ahelp chipsopt"	1	Yes
stem	Stem used for curve id	An alpha-numeric character sequence that does not contain a space	crv	No
symbol.angle	The angle, in degrees, of rotation for the curve symbols	-360.0 to 360.0	0.0	Yes
symbol.color	Color of the curve symbols	name or hex; see the Color section of "ahelp chipsopt"	default	Yes
symbol.fill	Should the curve symbols be filled or not	see the Booleans section of "ahelp chipsopt"	true	Yes
symbol.size	Size of the curve symbols	1 to 100	2	Yes
symbol.style	The shape of the glyph used as the curve symbols	see the Symbol Styles section of "ahelp chipsopt"	cross	Yes

Bugs

See the bugs pages on the ChIPS website for an up-to-date listing of known bugs.