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Last modified: December 2013

URL: http://cxc.harvard.edu/chips/ahelp/move_point.html
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AHELP for CIAO 4.9 ChIPS v1

move_point

Context: points

Synopsis

Moves the point to a new location.

Syntax

move_point(xval, yval)
move_point(xval, yval, mode)
move_point(id, xval, yval)
move_point(id, xval, yval, mode)

Description

The function arguments.

Argument Description
xval, yval The x and y coordinates to move. The mode parameter determines whether these are relative or absolute. Unless explicitly specified by the coord_sys field of the optional ChipsId argument, the coordinate system used to create the object is used.
mode The position is in absolute coordinates (mode=0) or relative (mode=1). The default is absolute.
id A ChipsId structure identifying the item.

The move_point command moves the point to a new position. The new location may be specified as an absolute position (default) or as relative offsets from the original location.

The following coordinate systems may be used to move a point: PIXEL, WINDOW_NORM, FRAME_NORM, PLOT_NORM, or DATA. The system is specified by setting the coord_sys field of the optional ChipsId structure which may be passed into the move_point routine. If a ChipsId is not provided, the default coordinate system of the point is used.

When a point is moved, it remains in its original coordinate system regardless of what coordinate system was used for the move. The move command translates the specified values to the coordinate system that the point is in before applying them to the point. This means that points that are originally placed in normalized coordinates and get relocated using data coordinates will not be clipped if they land outside the visible data range. Conversely, points in data coordinates which are moved using normalized coordinates to beyond the plot area will be clipped.

This command is equivalent to calling the move command with 'chips_point' specified as the object.

Example 1

chips> move_point(0.5, 0.5)

Move the current point to (0.5, 0.5) in the coordinate system used to create it.

Example 2

chips> id = ChipsId()
chips> id.coord_sys = PIXEL
chips> move_point(id, -20, 0, 1)

For a point specified in data coordinates, adjust the position by 20 pixels to the left in the x direction. Do not move it in the y direction.

Example 3

chips> id = ChipsId()
chips> id.point = 'all'
chips> id.coord_sys = DATA
chips> move_point(id, 40, 10, 1)

Shift all points by the same distance in data coordinates.

Bugs

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

See Also

points
add_point, current_point, delete_point, display_point, get_point, hide_point, set_point, shuffle_point

Last modified: December 2013
Smithsonian Institute Smithsonian Institute

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