NAME

gate - gate specific numbers from the input stream.

CONTENTS

Syntax
Description
Options
Examples
Copyright

gate [options] [file]

Numbers in the input stream within given gate ranges are replaced by aparticular <value>. Both time and amplitude ranges may be specified.The <value> may be a real number or the result of a particular <operation>.Results are written on the stdout in numbers of the same type as thatselected for input.

1. xrange, yrange

The ‘xrange’ specifies the time range and the ‘yrange’ specifies theamplitude range for the gating operation. Ranges are specified:

        xrange=a[-b]        yrange=a[-b]

The upper limit ‘b’ is optional, and when it is missing then the rangeis a single number, otherwise ‘a’ and ‘b’ are inclusive range limits.The xrange limits are in samples (no units) or may take time units (s or ms),in which case they are converted to samples using the given ‘samplerate’option. The yrange limits are real numbers.The strings "min" and "max" are recognised as extreme limits: the start andend of the input stream for the xrange, and the most positive and negativeamplitudes for the yrange.

2. value

The <value> may be a real number or an <operation>,in which case all input numbers within the gate range are operated on asappropriate. Abbreviated forms of the operation names are allowed.

<operation>:    exclude     exclude numbers in gate range from output    negate      negate numbers in gate range    count       print count of numbers in gate range on the stderr

3. type

The input and output datatype may be: char, short, int, float, double, ASCII.Ascii input is taken to be one number per line.

1. Replace all numbers <=0 by value 0 (ie. half-wave rectification).

        gate yrange=min-0 val=0  file

2. Replace all numbers <=0 by their inverse (ie. full-wave rectification).

        gate yrange=min-0 val=neg  file

3. Gate the onset of a signal: replace the first 20ms with zeroes.

        gate xrange=0-20ms yrange=min-max val=0 file

4. Exclude all numbers <=0

        gate yrange=min-0  val=exclude file

5. Exclude all numbers >0

        gate yrange=1-max val=exclude file

6. Delete lines 4 to 8 inclusive from ascii input (lines numbered 0,1,2,...)

    gate type=ASCII xrange=4-8 yrange=min-max val=exclude  file

7. Replace all numbers in the yrange -1 to +1 inclusive by 0

        gate yrange=-1-1 val=0  file

8. Replace all instances of number 10 by -10

        gate yrange=10 val=-10  file

9. Print a count of all numbers = 0

        gate yrange=0 val=count file

10. Print a count of all numbers < 0

        gate yrange=min--1  val=count file

options edwave step merge

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

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