PDL::Graphics::PGPLOT - PGPLOT enhanced interface for PDL
perldl> $a = pdl [1..100] perldl> $b = sqrt($a) perldl> line $b perldl> hold Graphics on HOLD perldl> $c = sin($a/10)*2 + 4 perldl> line $c
PDL::Graphics::PGPLOT is an interface to the PGPLOT graphical libraries.
Current display commands:
imag - Display an image (uses pgimag()/pggray() as appropriate) im - Shorthand to display an image with aspect ratio of 1 ctab - Load an image colour table line - Plot vector as connected points points - Plot vector as points errb - Plot error bars cont - Display image as contour map bin - Plot vector as histogram (e.g. bin(hist($data)) ) hi2d - Plot image as 2d histogram (not very good IMHO...) poly - Draw a polygon vect - Display 2 images as a vector field
Device manipulation commands:
hold - Hold current plot window range - allows overlays etc. release - Release back to autoscaling of new plot window for each command rel - short alias for 'release' env - Define a plot window, put on 'hold' dev - Explicitly set a new PGPLOT graphics device
The actual PGPLOT module is loaded only when the first of these commands is executed.
Notes: $transform
for image/cont etc. is used in the same way as the
TR()
array in the underlying PGPLOT FORTRAN routine but is, fortunately,
zero-offset.
For completeness: The transformation array connect the pixel index to a world coordinate such that:
X = tr[0] + tr[1]*i + tr[2]*j Y = tr[3] + tr[4]*i + tr[5]*j
In general variables are passed to the pgplot routines by using
get_dataref
to get the reference to the values. Before passing to pgplot routines
however, the data are checked to see if they are in accordance with the
format (typically dimensionality) required by the PGPLOT routines.
This is done using the routine checkarg
(internal to PGPLOT). This routine
checks the dimensionality of the input data. If there are superfluous
dimensions of size 1 they will be trimmed away until the dimensionality
is correct. Example:
Assume a piddle with dimensions (1,100,1,1) is passed to line
, which
expects its inputs to be vectors. checkarg
will then return a piddle
with dimensions (100). If instead the same piddle was passed to imag
,
which requires 2D piddles as output, checkarg
would return a piddle
with dimensionality (100, 1) (Dimensions are removed from the start)
Thus, if you want to provide support for another PGPLOT function, the structure currently look like this (there are plans to use the Options package to simplify the options parsing):
# Extract the hash(es) on the commandline ($arg, $opt)=_extract_hash(@_); <Check the number of input parameters> <deal with $arg> checkarg($x, 3); # For a hypothetical 3D routine. ... pgcube($n, $x->get_dataref); 1;
All routines in this package take a hash with options as an optional input. This options hash can be used to set parameters for the subsequent plotting without going via the PGPLOT commands.
This is implemented such that the plotting settings (such as line width,
line style etc.) are affected only for that plot, any global changes made,
say, with pgslw()
are preserved.
The following options are always parsed. Whether they have any importance
depend on the routine invoked - e.g. line style is irrelevant for imag
,
or the justify
option is irrelevant if the display is on 'hold'.
This is indicated in the help text for the commands below.
The options are not case sensitive and will match for unique substrings, but this is not encouraged as obscure options might invalidate what you thought was a unique substring.
In the listing below examples are given of each option. The actual option can then be used in a plot command by specifying it as an argument to the function wanted (it can be placed anywhere in the command list).
E.g:
$opt={COLOR=>2}; line $x, $y, $opt; # This will plot a line with red color
The following
$opt = {ARROW => {FS=>1, ANGLE=>60, VENT=>0.3, SIZE=>5}};
will make a broad arrow of five times the normal size.
Alternatively the arrow can be specified as a set of numbers corresponding to an extention to the syntax for pgsah. The equivalent to the above is
$opt = {ARROW => pdl([1, 60, 0.3, 5})};
For the latter the arguments must be in the given order, and if any are not given the default values of 1, 45, 0.3 and 1.0 respectively will be used.
$opt = {ARROWSIZE => 2.5};
EMPTY (-2) draw no box, axes or labels BOX (-1) draw box only NORMAL (0) draw box and label it with coordinates AXES (1) same as NORMAL, but also draw (X=0,Y=0) axes GRID (2) same as AXES, but also draw grid lines LOGX (10) draw box and label X-axis logarithmically LOGY (20) draw box and label Y-axis logarithmically LOGXY (30) draw box and label both axes logarithmically
TYPE
(set to
'relative' or 'absolute') and VALUE
(the amount to change the limits
by), or set to 1, which is equivalent to
BORDER => { TYPE => 'rel', VALUE => 0.05 }
$opt = {CHARSIZE => 1.5}
0 - WHITE 1 - BLACK 2 - RED 3 - GREEN 4 - BLUE 5 - CYAN 6 - MAGENTA 7 - YELLOW 8 - ORANGE 14 - DARKGRAY 16 - LIGHTGRAY
1 - SOLID 2 - OUTLINE 3 - HATCHED 4 - CROSS_HATCHED
$opt = {FILLTYPE => 'SOLID'};
(see below for an example of hatched fill)
1 - NORMAL 2 - ROMAN 3 - ITALIC 4 - SCRIPT
(Note that in a string, the font can be changed using the escape sequences
\fn
, \fr
, \fi
and \fs
respectively)
$opt = {FONT => 'ROMAN'};
gives the same result as
$opt = {FONT => 2};
min(height, width)
of the view surface, and PHASE to
set the offset the hatching. Alternatively this can be specified as a
1x3 piddle $hatch=pdl[$angle, $sep, $phase]
.
$opt = {FILLTYPE => 'HATCHED', HATCHING => {ANGLE=>30, SEPARATION=>4}};
Can also be specified as
$opt = {FILL=> 'HATCHED', HATCH => pdl [30,4,0.0]};
For another example of hatching, see poly.
pgenv()
command for more information.
1 - SOLID line 2 - DASHED 3 - DOT-DASH-dot-dash 4 - DOTTED 5 - DASH-DOT-DOT-dot
or using name (as given in capitals above). Thus the following two specifications both specify the line to be dotted:
$opt = {LINESTYLE => 4}; $varopt = {LINESTYLE => 'DOTTED'};
The names are not case sensitive, but the full name is required.
$opt = {LINEWIDTH => 10}; # A rather fat line
A more detailed listing of the functions and their usage follows. For all functions we specify which options take effect and what other options exist for the given function.
Open PGPLOT graphics device
Usage: dev $device, [$nx,$ny];
$device
is a PGPLOT graphics device such as ``/xserve'' or ``/ps'',
if omitted defaults to last used device (or value of env
var PGPLOT_DEV
if first time).
$nx
, $ny
specify sub-panelling.
Define a plot window, and put graphics on 'hold'
Usage: env $xmin, $xmax, $ymin, $ymax, [$justify, $axis]; env $xmin, $xmax, $ymin, $ymax, [$options];
$xmin
, $xmax
, $ymin
, $ymax
are the plot boundaries.
$justify
is a boolean value (default is 0);
if true the axes scales will be the same (see justify).
$axis
describes how the axes should be drawn (see
axis) and defaults to 0.
If the second form is used, $justify and $axis can be set in the options hash, for example:
env 0, 100, 0, 50, {JUSTIFY => 1, AXIS => 'GRID', CHARSIZE => 0.7};
Display an image (uses pgimag()
/pggray()
as appropriate)
Usage: imag ( $image, [$min, $max, $transform], [$opt] )
Notes: $transform
for image/cont etc. is used in the same way as the
TR()
array in the underlying PGPLOT FORTRAN routine but is,
fortunately, zero-offset.
There are several options related to scaling. By default, the image is scaled to fit the PGPLOT default viewport on the screen. Scaling, aspect ratio preservation, and 1:1 pixel mapping are available. (1:1 pixel mapping GREATLY increases the speed of pgimag, and is useful for, eg, movie display; but it's not recommended for final output as it's not device-independent.)
Options recognised:
ITF - the image transfer function applied to the pixel values. It may be one of 'LINEAR', 'LOG', 'SQRT' (lower case is acceptable). It defaults to 'LINEAR'. MIN - Sets the minimum value to be used for calculation of the display stretch MAX - Sets the maximum value for the same TRANSFORM - The transform 'matrix' as a 6x1 vector for display PIX - Sets the image pixel aspect ratio. By default, imag stretches the image pixels so that the final image aspect ratio fits the viewport exactly. Setting PIX=>1 causes the image aspect ratio to be preserved. (the image is scaled to avoid cropping, unless you specify scaling manually). Larger numbers yield "landscape mode" pixels. PITCH - Sets the number of image pixels per screen unit, in the Y direction. The X direction is determined by PIX, which defaults to 1 if PITCH is specified and PIX is not. PITCH causes UNIT to default to "inches" so that it's easy to say 100dpi by specifying {PITCH=>100}. Larger numbers yield higher resolution (hence smaller appearing) images. UNIT - Sets the screen unit used for scaling. Must be one of the PGPLOT supported units (inch, mm, pixel, normalized). You can refer to them by name or by number. Defaults to pixels if not specified. SCALE - Syntactic sugar for the reciprocal of PITCH. Makes the UNIT default to "pixels" so you can say "{SCALE=>1}" to see your image in device pixels. Larger SCALEs lead to larger appearing images.
The following standard options influence this command:
AXIS, BORDER, JUSTIFY
To see an image with maximum size in the current window, but square pixels, say: imag $a,{PIX=>1} An alternative approach is to try: imag $a,{JUSTIFY=>1} To see the same image, scaled 1:1 with device pixels, say: imag $a,{SCALE=>1} To see an image made on a device with 1:2 pixel aspect ratio, with X pixels the same as original image pixels, say imag $a,{PIX=>0.5,SCALE=>2} To display an image at 100 dpi on any device, say: imag $a,{PITCH=>100} To display an image with 100 micron pixels, say: imag $a,{PITCH=>10,UNIT=>'mm'}
Display an image with correct aspect ratio
Usage: imag1 ( $image, [$min, $max, $transform], [$opt] )
Notes: This is syntactic sugar for imag({PIX=>1}).
Load an image colour table.
Usage:
ctab ( $name, [$contrast, $brightness] ) # Builtin col table ctab ( $ctab, [$contrast, $brightness] ) # $ctab is Nx4 array ctab ( $levels, $red, $green, $blue, [$contrast, $brightness] ) ctab ( '', $contrast, $brightness ) # use last color table
Note: See PDL::Graphics::LUT for access to a large number of colour tables.
Plot vector as connected points
If the 'MISSING' option is specified, those points in the $y
vector
which are equal to the MISSING value are not plotted, but are skipped
over. This allows one to quickly draw multiple lines with one call to
line
, for example to draw coastlines for maps.
Usage: line ( [$x,] $y, [$opt] )
The following standard options influence this command:
AXIS, BORDER, COLO(U)R, JUSTIFY, LINESTYLE, LINEWIDTH, MISSING
$x = sequence(10)/10.; $y = sin($x)**2; # Draw a red dot-dashed line line $x, $y, {COLOR => 'RED', LINESTYLE=>3};
Plot vector as points
Usage: points ( [$x,] $y, [$symbol(s)], [$opt] )
Options recognised:
SYMBOL - Either a piddle with the same dimensions as $x, containing the symbol associated to each point or a number specifying the symbol to use for every point, or a name specifying the symbol to use according to the following (recognised name in capital letters): 0 - SQUARE 1 - DOT 2 - PLUS 3 - ASTERISK 4 - CIRCLE 5 - CROSS 7 - TRIANGLE 8 - EARTH 9 - SUN 11 - DIAMOND 12- STAR PLOTLINE - If this is >0 a line will be drawn through the points.
The following standard options influence this command:
AXIS, BORDER, CHARSIZE, COLOUR, JUSTIFY, LINESTYLE, LINEWIDTH
$y = sequence(10)**2+random(10); # Plot blue stars with a solid line through: points $y, {PLOTLINE => 1, COLOUR => BLUE, SYMBOL => STAR};
Plot error bars (using pgerrb()
)
Usage:
errb ( $y, $yerrors, [$opt] ) errb ( $x, $y, $yerrors, [$opt] ) errb ( $x, $y, $xerrors, $yerrors, [$opt] ) errb ( $x, $y, $xloerr, $xhierr, $yloerr, $yhierr, [$opt])
Options recognised:
TERM - Length of terminals in multiples of the default length SYMBOL - Plot the datapoints using the symbol value given, either as name or number - see documentation for 'points'
The following standard options influence this command:
AXIS, BORDER, CHARSIZE, COLOUR, JUSTIFY, LINESTYLE, LINEWIDTH
$y = sequence(10)**2+random(10); $sigma=0.5*sqrt($y); errb $y, $sigma, {COLOUR => RED, SYMBOL => 18};
Display image as contour map
Usage: cont ( $image, [$contours, $transform, $misval], [$opt] )
Notes: $transform
for image/cont etc. is used in the same way as the
TR()
array in the underlying PGPLOT FORTRAN routine but is,
fortunately, zero-offset.
Options recognised:
CONTOURS - A piddle with the contour levels FOLLOW - Follow the contour lines around (uses pgcont rather than pgcons) If this is set >0 the chosen linestyle will be ignored and solid line used for the positive contours and dashed line for the negative contours. LABELS - An array of strings with labels for each contour LABELCOLOUR - The colour of labels if different from the draw colour This will not interfere with the setting of draw colour using the colour keyword. MISSING - The value to ignore for contouring NCONTOURS - The number of contours wanted for automatical creation, overridden by CONTOURS TRANSFORM - The pixel-to-world coordinate transform vector
The following standard options influence this command:
AXIS, BORDER, COLOUR, JUSTIFY, LINESTYLE, LINEWIDTH
$x=sequence(10,10); $ncont = 4; $labels= ['COLD', 'COLDER', 'FREEZING', 'NORWAY'] # This will give four blue contour lines labelled in red. cont $x, {NCONT => $ncont, LABELS => $labels, LABELCOLOR => RED, COLOR => BLUE}
Plot vector as histogram (e.g. bin(hist($data))
)
Usage: bin ( [$x,] $data )
Options recognised:
CENTRE - if true, the x values denote the centre of the bin otherwise they give the lower-edge (in x) of the bin CENTER - as CENTRE
The following standard options influence this command:
AXIS, BORDER, COLOUR, JUSTIFY, LINESTYLE, LINEWIDTH
Plot image as 2d histogram (not very good IMHO...)
Usage: hi2d ( $image, [$x, $ioff, $bias], [$opt] )
Options recognised:
IOFFSET - The offset for each array slice. >0 slants to the right <0 to the left. BIAS - The bias to shift each array slice up by.
The following standard options influence this command:
AXIS, BORDER, JUSTIFY
Note that meddling with the ioffset
and bias
often will require you to
change the default plot range somewhat. It is also worth noting that if
you have TriD working you will probably be better off using
mesh3d or
a similar command - see the PDL::Graphics::TriD manpage.
$r=sequence(100)/50-1.0; $y=exp(-$r**2)*transpose(exp(-$r**2)) hi2d $y, {IOFF => 1.5, BIAS => 0.07};
Draw a polygon
Usage: poly ( $x, $y )
Options recognised:
The following standard options influence this command:
AXIS, BORDER, COLOUR, FILLTYPE, HATCHING, JUSTIFY, LINESTYLE, LINEWIDTH
# Fill with hatching in two different colours $x=sequence(10)/10; # First fill with cyan hatching poly $x, $x**2, {COLOR=>5, FILL=>3}; hold; # Then do it over again with the hatching offset in phase: poly $x, $x**2, {COLOR=>6, FILL=>3, HATCH=>{PHASE=>0.5}}; release;
Display 2 images as a vector field
Usage: vect ( $a, $b, [$scale, $pos, $transform, $misval] )
Notes: $transform
for image/cont etc. is used in the same way as the
TR()
array in the underlying PGPLOT FORTRAN routine but is,
fortunately, zero-offset.
This routine will plot a vector field. $a
is the horizontal component
and $b
the vertical component.
Options recognised:
SCALE - Set the scale factor for vector lengths. POS - Set the position of vectors. <0 - vector head at coordinate >0 - vector base at coordinate =0 - vector centered on the coordinate TRANSFORM - The pixel-to-world coordinate transform vector MISSING - Elements with this value are ignored.
The following standard options influence this command:
ARROW, ARROWSIZE, AXIS, BORDER, CHARSIZE, COLOUR, JUSTIFY, LINESTYLE, LINEWIDTH
$a=rvals(11,11,{Centre=>[5,5]}); $b=rvals(11,11,{Centre=>[0,0]}); vect $a, $b, {COLOR=>YELLOW, ARROWSIZE=>0.5, LINESTYLE=>dashed};
Karl Glazebrook [kgb@aaoepp.aao.gov.au] modified by Jarle Brinchmann (jarle@ast.cam.ac.uk), docs mangled by Tuomas J. Lukka (lukka@fas.harvard.edu) and Christian Soeller (c.soeller@auckland.ac.nz)
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