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spoke


Manual Reference Pages  - SPOKE (1)

NAME

spoke - Extract points from an auditory image which lie along a spoke (ie. radial line) of the spiral map of the auditory image.

CONTENTS

Syntax
Description
Options
Units Of Angle
Summary Statistics
Examples
Copyright

SYNTAX

spoke [arguments] [file]

DESCRIPTION

Read auditory image frames output by either gensai or genspl. (Note that their default options are different, particularly pwidth, nwidth, and dencf). The frames must be preceded by an AIM header. For each frame, extract a set of points and write them on the stdout as binary shorts. The set of points lie along a spoke of the spiral map of the auditory image. The location of the spoke in the spiral map is specified as a sector of given orientation and angle. (See options theta and dtheta).

OPTIONS

1. frames.

When the input consists of a cartoon of multiple frames then single frames or a range of sequential frames may be selected from the input using:

  frames=a[-b]

The upper limit ‘b’ is optional, and when it is missing then the range is a single frame, otherwise ‘a’ and ‘b’ are inclusive range limits. The strings "min" and "max" are recognised as extreme limits, otherwise the values of ‘a’ and ‘b’ are frame numbers: 0,1,2,...

The frame selector may also take time units (s, or ms) to specify frames "closest" to the given time, being the frame number which is the greatest integer multiple of the framestep (‘frstep_epn’ or ‘frstep_aid’) which does not exceed the given time, measured from the start of the input file.

2. Header.

When Header=on, the output is preceded by an AIM header appropriate for genepn output. In this way, the output of the spoke program can be plotted using genepn. For example:

  spoke Header=on file > file.epn
  genepn useprevious=on file

The option flag:
  Header=off

causes the header to be suppressed from the output.

3. theta.

Theta is the angle of the sector which contains the spoke. It is the angle between the datum (which can be imagined as the 3 o’clock position on the spiral plot) and the centre of the angle subtended by the sector.

Theta is given as a real number, appended with optional units. (See notes on units of angle, below). Theta can also take a special value:

  theta=max

In this case, a sector of size dtheta (see below) is rotated in small increments around the spiral. At each step, the sum of the points within the sector at that angle is extracted. The sector with the maximum sum is output. The angle theta of this maximum sector is also printed on the stderr.

The size of the small increments can be set using the silent option dangle (delta angle). When dangle=1min, the search for the max sector is through 60 sectors around the spiral.

4. dtheta.

Delta theta (dtheta) is the angle subtended by the sector, describing the size of the sector. Delta theta is given as a real number, appended with optional units. (See notes on units of angle, below).

5. sectorstat.

The name of the function used to calculated the summary statistic of points within the sector at a given radius from the centre of the spiral. Any of the available summary statistical functions can be used (see notes on summary statistics below).

6. spokestat.

The name of the function used to calculated the summary statistic of each spoke. This is the summary of the points at successive radii, which have already been summarised across the sector angle by sectorstat. Any of the available summary statistical functions can be used (see notes on summary statistics below).

7. Silent options.

There are a few silent (ie. not commonly used) options which are explained using:

  spoke help=all

UNITS OF ANGLE

Any of the angle options (theta, dtheta, dangle) may be given as a real number with appended units. If no units are appended, the number is taken to be a fraction of the unit circle. Otherwise, the list of available units is: deg, min, rad, pi.

SUMMARY STATISTICS

The list of available statistical functions is: mean, max, sum, cg. The cg (centre of gravity) function returns the mean of the input values weighted by their position in the input array. The source code (spoke.c) contains details of how the list of functions can easily be extended.

EXAMPLES

echo q | genspl output=stdout file | spoke theta=0 dtheta=10deg > file.epn
  to plot the spoke:
genepn useprevious=on file
  or, alternatively:
hdr file.epn | x11plot

COPYRIGHT

Copyright (c) Applied Psychology Unit, Medical Research Council, 1995

Permission to use, copy, modify, and distribute this software without fee is hereby granted for research purposes, provided that this copyright notice appears in all copies and in all supporting documentation, and that the software is not redistributed for any fee (except for a nominal shipping charge). Anyone wanting to incorporate all or part of this software in a commercial product must obtain a license from the Medical Research Council.

The MRC makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.

THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


SunOS 5.6 SPOKE (1) 8 July 1997
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