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merplot - draws line graphs of data output from ERP program merp
plot_device cmdfile [-pause] [-baseline start stop] [-nobaseline] [-filter
filtertype cutoff [cutoff]]
merplot is a program which plots
(linegraph) data on a graphics device (plot_device) according to specifications
in cmdfile (see COMMAND FILE section). merplot calculates the mean amplitude
across a time window specified by the user. The program allows arbitrary
colors, linestyles, and any of eight different symbols (markertype) to
differentiate among traces. merplot allows labeling of both the x and y
axis, as well as legends at the top and bottom of the page.
- If the -pause option is specified, the merplot program will pause between
plotting pages when there are multiple pages and the plotting device clears
its drawing surface for new pages (a hardcopy device like a printer does
not clear its drawing surface, it ejects a page and starts with a new drawing
- -baseline start stop
- This option is identical to the baseline command
described in the COMMAND FILE section below. It overrides any baseline
(or nobaseline) specified in the command file.
- This option is
identical to the nobaseline command described in the COMMAND FILE section
below. It overrides any baseline specified in the command file.
- -filter filtertype
- This option is identical to the filter command described
in the COMMAND FILE section below. It overrides any filter specified in
the command file.
The following is a description of the command
file syntax. Optional command parameters are enclosed in brackets and
described at the end.
Three commands must appear in the cmdfile: (1) file,
(2) bin, and (3)
the pagelayout - endpagelayout pair commands. The pagelayout
command specifies the order in which electrodes will be displayed along
the horizontal axis. merplot will create several groups of connected line
segments; you specify the electrodes you want to be connected by connecting
their labels with hyphens. The electrode groups are then separated by
white space (spaces, tabs, newlines) After the electrode groups have been
specified the endpagelayout command should follow on a line by itself. The
syntax for the file, bin, and the pagelayout - endpagelayout pair commands
are as follows:
- file filename
- Specify the file name of the ERP data file.
The file command must be appear at some point in cmdfile before the bin
command. More than one file command may be present in cmdfile, to allow
bins to be specified from different files.
- bin bin# markertype [linestyle]
[linethickness] [color] [markersize]
- Specify the bin number. The bin command
associates to the nearest file command above it, therefore a file command
must appear at some point in cmdfile before the bin command. markertype
is one of "circle", "triangle", "square", "hexagon", "fcircle", "ftriangle",
"fsquare", "fhexagon", or "none". In addition to these, there are variations
with a small line segment drawn through the markertype; these are specified
by preceding the geometric type with the letter ’l’, as in "lcircle".
- chanlab-chanlab-... [chanlab-chanlab-...]
- Specify the layout of the
plot. Channel refers to electrode channel labels NOT channel numbers. The
pagelayout command must be on a line by itself. The channel label specifiers
can be on multiple lines, and the endpagelayout command to end the layout
description must be on a line by itself. For example, you might specify
f7-l41-wl-o1 cz-pz-bl f8-41-wr-wl
to make a plot with three groups of connected line segments for the mean
amplitude measures of the specified electrodes.
The following is a description of the rest of the commands that can be
used in a command file.
- starttime time
- Specify the start of the time window
(ms), which is when to begin calculating the mean amplitude of the ERP.
Default is 0.
- time_slice time
- Specify the duration (ms) of the time window,
which is the length of time over which the mean amplitude is to be calculated.
Default is 100.
- nslices number of plots
- Specify the number of graphs that
will be calculated. Default is 1.
- step_size time
- Specify the period (ms)
to use for the start of each time window when multiple graphs are calculated.
The default is time_slice.
- max max amplitude
- Specify the maximum amplitude
on the y axis of the plot. Default is 10. If max is less than min, the plot
will be "reversed" (i.e., smaller amplitudes will be on top of plot, larger
amplitudes on bottom).
- min min amplitude
- Specify the minimum amplitude
on the y axis of the plot. Default is -10.
- zeroline [y value]
- Optional dashed
line that runs parallel to the x axis. It can be placed anywhere on the
plot. If no y value is given then it is placed at zero.
- yticks number of
- Specify the number of ticks that will be placed on the y axis. If
the number specified results in y tick labels that are non-integer, an appropriate
precision (see ytickformat) will automatically be applied to the labels.
If both yticks and ytickinterval are specified, ytickinterval has precedence.
The default is 0.
- ytickinterval interval
- Specify the interval (in uV) for
placing ticks on the y axis. If the value specified results in y tick labels
that are non-integer, an appropriate precision (see ytickformat) will automatically
be applied to the labels. If both yticks and ytickinterval are specified,
ytickinterval has precedence.
- ytickformat precision [color] [linethickness]
- Specify the format of the tickmarks on the y axis. Precision
is the number of digits that should appear after the decimal point for
the y tick labels. Note that precision may be overridden as a result of
certain values specified by yticks and ytickinterval.
- xtickformat [color] [linethickness] [textsize] [font]
- Specify the format
of the tickmarks on the x axis.
- title "text" [color] [linethickness] [textsize] [font]
- Specify the text
that will appear at the top of each plot. The text must be enclosed in
quotes. The specified text will be appended with the time window to which
the plot appears. Another command, notitletime tells merplot to NOT append
the time window to the text string.
- text xpos ypos "text" [color] [linethickness]
[textsize] [font] [laborigin]
- Put a text string at an arbitrary location
on the plot page. Xpos and ypos are specified as a fractional portion
of the width and height of the plot page respectively. Xpos increases from
left to right, and Ypos increases from the bottom of the page to the top.
Thus the lower left hand corner of the page has xpos=0, ypos=0; the middle
of the plot page has xpos=0.5, ypos=0.5; and the upper right hand corner
of the page has xpos=1.0, ypos=1.0.
- toplegend "text" [color] [linethickness]
- Display a legend at the top of the page. Several toplegend
commands may appear in a command file, in which case the legends will appear
one on top of the other, the first being the topmost. The "text" string
can contain marker variables for drawing the various markers at any position
in the text string. For example, to draw a filled circle at the beginning
of a legend, the toplegend commmand might look like this:
toplegend "%v This is a filled circle" fcircle
As you may have surmised, every occurence of "%v" in the text string must
have a corresponding markertype designation (see the bin command) after
the text string.
- bottomlegend "text" [color] [linethickness] [textsize]
- This is essentially the same as the toplegend command, only the
legends are displayed at the bottom of the page.
- ytitle "text" [color]
[linethickness] [textsize] [font]
- Specify the text that will appear along
the y axis. The text must be enclosed in quotes.
- plotsperpage number of
- Specify the number of plots per page. Default is the number of nslices.
- Causes the plots to be all be displayed in one column.
- baseline start stop
- This command is used to alter the interval used to
calculate the baseline voltage which is subtracted from every point in
the data prior to measurement. start and stop are decimal integers which
denote the beginning and ending latencies (in ms) of the portion of data
which are to be averaged together to form the baseline voltage (note: prior
to 2008-09-10 the data point corresponding to the stop latency was included
in the baseline average; after 2008-09-10 it is excluded). They are relative
to stimulus onset, so if one wanted to use the 50 ms prior to stimulus
onset as the baseline interval, one would type baseline -50 0. If no interval
is specified, the default is to baseline using the presampling period to
calculate the baseline voltage.
- This command specifies to not
subtract a baseline voltage from the data prior to measurement. The default
is to baseline using the presampling period to calculate the baseline voltage.
- filter filtertype cutoff [cutoff]
- Filter the data before measuring. filtertype
may be "lp" for lowpass, "hp" for highpass, or "bp" for bandpass. cutoff
is the cutoff frequency to use for the filter. If a bandpass filter is
used, both a low and high cutoff frequency must be specified.
enclosed in square brackets are optional, and can appear in any order.
They are specified as follows:
- font - one of simplex, duplex, complex,
- textsize - textsize=n, where n is a positive number (can have
- a decimal point). Note that no spaces are allowed between "textsize", "=",
- color - color=n, where n is a positive integer, which is
dependent (on monochrome devices, 0 is invisible, 1 is that devices color).
- linethickness - one of verythin, thin, medium, thick, or verythick.
- one of solid, dotted, dashed, or dotdash
- markersize - markersize=n, where
n is a positive number.
- Note that no spaces are allowed between "markersize",
"=", and "n".
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