PGPLOT Extensions Part II

pgCons

Draws a contour map of an array. The map is truncated if necessary at the boundaries of the viewport. Each contour line is drawn with the current line attributes (color index, style, and width). This routine, unlike pgCont, does not draw each contour as a continuous line, but draws the straight line segments composing each contour in a random order. It is thus not suitable for use on pen plotters, and it usually gives unsatisfactory results with dashed lines.

Calling sequence:

pgCons <a> <i1> <i2> <j1> <j2> <c> <tr> where: a : 2-dimensional data array. i1,i2 : range of first index to be contoured (inclusive). j1,j2 : range of second index to be contoured (inclusive). c : 1-dimensional array of contour levels (in the same units as the data in array a). tr : 1-dimensional array defining a transformation between the i,j grid of the array and the world coordinates. The world coordinates of the array point a(i,j) are given by: x = tr(1) + tr(2)*i + tr(3)*j y = tr(4) + tr(5)*i + tr(6)*j Usually tr(3) and tr(5) are zero - unless the coordinate transformation involves a rotation or shear. For example: pgCons a 1 10 2 20 {c-levels} {0 1 0 0 0 1}

pgCont

Draws a contour map of an array. The map is truncated if necessary at the boundaries of the viewport. Each contour line is drawn with the current line attributes (color index, style, and width); except that if "auto" is specified (see below), the line style is set by pgCont to 1 (solid) for positive contours or 2 (dashed) for negative contours.

Calling sequence:

pgCont <a> <i1> <i2> <j1> <j2> <c> <tr> [d:auto | current] where: a : 2-dimensional data array. i1, i2 : range of first index to be contoured (inclusive). j1, j2 : range of second index to be contoured (inclusive). c : 1-dimensional array of NC contour levels; dimension at least NC. tr : 1-dimensional array defining a transformation between the i,j grid of the array and the world coordinates. The world coordinates of the array point a(i,j) are given by: x = tr(1) + tr(2)*i + tr(3)*j y = tr(4) + tr(5)*i + tr(6)*j Usually tr(3) and tr(5) are zero - unless the coordinate transformation involves a rotation or shear. auto : The line-style is chosen automatically as described above. current : The current setting of line-style is used for all the contours. For example: pgCont a 1 10 2 20 {c-levels} {0 1 0 0 0 1} current

pgConx

Draws a contour map of an array using a user-supplied plotting routine. This routine should be used instead of pgCont when the data are defined on a non-rectangular grid. pgCont permits only a linear transformation between the (i,j) grid of the array and the world coordinate system (x,y), but pgConx permits any transformation to be used, the transformation being defined by a user-supplied subroutine. The nature of the contouring algorithm, however, dictates that the transformation should maintain the rectangular topology of the grid, although grid-points may be allowed to coalesce. As an example of a deformed rectangular grid, consider data given on the polar grid theta=0.1n(pi/2), for n=0,1,...,10, and r=0.25m, for m=0,1,..,4. This grid contains 55 points, of which 11 are coincident at the origin. The input array for pgConx should be dimensioned (11,5), and data values should be provided for all 55 elements. pgConx can also be used for special applications in which the height of the contour affects its appearance, e.g., stereoscopic views.

The map is truncated if necessary at the boundaries of the viewport. Each contour line is drawn with the current line attributes (color index, style, and width); except that if auto is specified (see below), the line style is set by pgConx to 1 (solid) for positive contours or 2 (dashed) for negative contours.

Calling sequence:

pgConx <a> <i1> <i2> <j1> <j2> <c> <x-trans> <y-trans> where: a : 2-dimensional data array. i1, i2 : range of first index to be contoured (inclusive). j1, j2 : range of second index to be contoured (inclusive). c : i-dimensional array of NC contour levels; dimension at least NC. x-trans : x-coordinate transformation. The variables x, y and z can be used be the transformation script. y_trans : y-coordinate transformation. The variables x, y and z can be used be the transformation script. auto : The line-style is chosen automatically as described above. current : The current setting of line-style is used for all the contours. For example: pgConx a i1 i2 j1 j2 {c-levels} {$x*cos($y)} {$x*sin($y)}

pgErrx

Plots horizontal error bars. This routine draws an error bar only; to mark the data point in the middle of the error bar, an additional call to pgPoint or pgErry is required.

Calling sequence:

pgErrx <x1> <x2> <y> [t, d:0.0] where: x1 : world x-coordinates of lower end of the error bars. x2 : world x-coordinates of upper end of the error bars. y : world y-coordinates of the data. t : length of terminals to be drawn at the ends of the error bar, as a multiple of the default length; if t = 0.0, no terminals will be drawn. Note: the dimension of arrays x1, x2, and y must be equal. If one element is defined then, x1, x2, and y may be scalar variables, or expressions, eg: pgErrx x-sigma x+sigma y

pgErry

Plots vertical error bars. This routine draws an error bar only; to mark the data point in the middle of the error bar, an additional call to pgPtext or pgErrx is required.

Calling sequence:

pgErry x y1 y2 [t, d:0.0] where: x : world x-coordinates of the data. y1 : world y-coordinates of top end of the error bars. y2 : world y-coordinates of bottom end of the error bars. t : length of terminals to be drawn at the ends of the error bar, as a multiple of the default length; if t = 0.0, no terminals will be drawn. Note: the dimension of arrays x, y1, and y2 must be equal. If only one element is specified then, x, y1, and y2 may be scalar variables or expressions, eg: pgErry x y+sigma y-sigma

pgFunt

Draw a curve defined by parametric equations x = fx(t), y = fy(t).

Calling sequence:

pgFunt <fx> <fy> <n> <tmin> <tmax> [d:current | new] where: fx : A real function of variable t that evaluates X-coordinate. fy : A real function of variable t that evaluates Y-coordinate. n : the number of points required to define the curve. The functions fx and fy will each be called n+1 times. tmin : the minimum value for the parameter t. tmax : the maximum value for the parameter t. current : the curve is plotted in the current window and viewport new : pgEnv is called automatically by pgFunt to start a new plot with automatic scaling.

pgFunx

Draws a curve defined by the equation y = fy(x), where fy is a user-supplied subroutine.

Calling sequence:

pgFunx <fy> <n> <xmin> <xmax> [d:current | new] where: fy : A real function of variable x that evaluates Y value at a given X-coordinate. The variable x is available for use by the function fy n : the number of points required to define the curve. The function fy will be called n+1 times. If n is greater than 1000, 1000 will be used instead. If n is less than 1, nothing will be drawn. xmin : the minimum value of X. xmax : the maximum value of X. current : the curve is plotted in the current window and viewport new : pgEnv is called automatically by pgFunx to start a new plot with X limits (xmin, xmax) and automatic scaling in Y.

pgFuny

Draws a curve defined by the equation x = fx(y), where fy is a user-supplied subroutine.

Calling sequence:

pgFuny <fx> <n> <ymin> <ymax> [d:current | new] where: fx : A real function of variable y that evaluates X value at a given Y-coordinate. The variable y is available for use by the function fx n : the number of points required to define the curve. The function fx will be called n+1 times. If n is greater than 1000, 1000 will be used instead. If n is less than 1, nothing will be drawn. ymin : the minimum value of Y. ymax : the maximum value of Y. current : the curve is plotted in the current window and viewport new : pgEnv is called automatically by pgFuny to start a new plot with Y limits (ymin, ymax) and automatic scaling in X.

pgGray

Draws gray-scale map of an array in current window. The subsection of the array 'a' defined by indices (i1:i2, j1:j2) is mapped onto the view surface world-coordinate system by the transformation matrix tr. The resulting quadrilateral region is clipped at the edge of the window and shaded with the shade at each point determined by the corresponding array value. The shade is a number in the range 0 to 1 obtained by linear interpolation between the background level (bg) and the foreground level (fg), i.e., shade = [a(i,j) - bg] / [fg - bg]

The background level bg can be either less than or greater than the foreground level fg. Points in the array that are outside the range bg to fg are assigned shade 0 or 1 as appropriate.

The algorithm used by pgGray is device-dependent. On devices that have only two color indices (0 and 1), the background color is the color assigned to color index 0, the foreground color is the color assigned to color index 1, and pgGray uses a "dithering" algorithm to fill in pixels in the two colors, with the shade (computed as above) determining the faction of pixels that are assigned color index 1.

On devices that have more than 16 color indices, pgGray may use color indices outside the range 0-15 to provide more than two gray shades. Note that pgGray may change the color representation of these color indices, but it will not change the representation of indices 0-15.

On most devices, the shaded region is "opaque", i.e., it obscures all graphical elements previously drawn in the region. But on devices that do not have erase capability, the background shade is "transparent" and allows previously-drawn graphics to show through.

The transformation matrix tr is used to calculate the world coordinates of the center of the "cell" that represents each array element. The world coordinates of the center of the cell corresponding to array element a(i,j) are given by:

x = tr(1) + tr(2)*i + tr(3)*j y = tr(4) + tr(5)*i + tr(6)*j

Usually tr(3) and tr(5) are zero -- unless the coordinate transformation involves a rotation or shear. The corners of the quadrilateral region that is shaded by pgGray are given by applying this transformation to (i1-0.5,j1-0.5), (i2+0.5, j2+0.5).

Calling sequence:

pgGray <a> <i1> <i2> <j1> <j2> <fg> <bg> <tr> where: a : the 2-dimensional array to be plotted. i1, i2 : the inclusive range of the first index (i) to be plotted. j1, j2 : the inclusive range of the second index (j) to be plotted. fg : the array value which is to appear with shade 1 ("foreground"). bg : the array value which is to appear with shade 0 ("background"). tr : a 1-dimensional transformation matrix between array grid and world coordinates (tr[6]).

pgHi2d

Plots a series of cross-sections through a 2D data array. Each cross-section is plotted as a hidden line histogram. The plot can be slanted to give a pseudo-3D effect - if this is done, the call to pgEnv may have to be changed to allow for the increased x range that will be needed.

Calling sequence:

pgGray <data> <ix1> <ix2> <iy1> <iy2> <x> <ioff> <bias> [d:center | lowedge] where: data : 2-dimensional data array to be plotted. ix1 ix2 iy1 iy2 : pgHi2d plots a subset of the input array data. This subset is delimited in the first (x) dimension by ix1 and ix2 and the 2nd (y) by iy1 and iy2, inclusively. Note: iy2 < iy1 is permitted, resulting in a plot with the cross-sections plotted in reverse Y order. However, ix2 must be => ix1. x : the abscissae of the bins to be plotted. That is, x(1) should be the x value for data(ix1,iy1), and x should have (ix2-ix1+1) elements. The program has to assume that the x value for data(X,Y) is the same for all y. ioff : an offset in array elements applied to successive cross-sections to produce a slanted effect. A plot with ioff > 0 slants to the right, one with ioff < 0 slants left. bias : a bias value applied to each successive cross- section in order to raise it above the previous cross-section. This is in the same units as the data. center : the x values denote the center of the bins lowedge : the x values denote the lower edges (in x) of the bins.

pgHist

Draws a histogram of N values of a variable in array data(1...N) in the range datmin to datmax using nbin bins. Note that array elements which fall exactly on the boundary between two bins will be counted in the higher bin rather than the lower one; and array elements whose value is less than datmin or greater than or equal to datmax will not be counted at all.

Calling sequence:

pgHist <data> <datmin> <datmax> <nbin> [d:current | new] where: data : 1-dimensional array with data values. datmin : the minimum data value for the histogram. datmax : the maximum data value for the histogram. nbin : the number of bins to use: the range datmin to datmax is divided into nbin equal bins and the number of data values in each bin is determined by pgHist. nbin may not exceed 200. current : the histogram is plotted in the current window and viewport new : pgEnv is called automatically by pgHist to start a new plot (the x-limits of the window will be datmin and datmax; the y-limits will be chosen automatically). Note: The pen position is changed to (datmax,0.0) in world coordinates.

pgCurse

Reads the cursor position and a character typed by the user. The position is returned in world coordinates. PGCURSE positions the cursor at the position specified, allows the user to move the cursor using the joystick or arrow keys or whatever is available on the device. When he has positioned the cursor, the user types a single character on the keyboard;

pgCurse then returns this character and the new cursor position (in world coordinates); if the device has no cursor or if some other error occurs, the value CHAR(0) [ASCII NULL character] is returned.

Calling sequence:

pgCurse <x> <y> where: x : the world x-coordinate of the cursor. y : the world y-coordinate of the cursor. Note: The cursor coordinates (x,y) may be changed by pgCurse even if the device has no cursor or if the user does not move the cursor. Under these circumstances, the position returned in (x,y) is that of the pixel nearest to the requested position.

pgLcurse

Interactive routine for user to enter a polyline by use of the cursor. Routine allows user to Add and Delete vertices; vertices are joined by straight-line segments.

Calling sequence:

pgLcurse <coord> where: coord : variable name. If coord variable does not exists it is defined. Upon return coord contains the new x and y coordinates in the form {{x-coord} {y-coord}} Note 1: On return from the program, cursor points are returned in the order they were entered. Routine may be (re-)called with points already defined in coord, and they will be plotted first, before editing. Note 2: User commands: the user types single-character commands after positioning the cursor: the following are accepted: A (Add) - add point at current cursor location. D (Delete) - delete last-entered point. X (exit) - leave subroutine.

pgNcurse

Interactive routine for user to enter data points by use of the cursor. Routine allows user to Add and Delete points. The points are returned in order of increasing x-coordinate, not in the order they were entered.

Calling sequence:

pgNcurse <coord> [symbol, d=-1] where coord : variable name. If coord variable does not exists it is defined. Upon return coord contains the new x and y coordinates in the form {{x-coord} {y-coord}} symbol : code number of symbol to use for marking entered points (see pgPoint). Note 1: On return from the program, cursor points are returned in increasing order of X. Routine may be (re-)called with points already defined in coord, and they will be plotted first, before editing. Note 2: User commands: the user types single-character commands after positioning the cursor: the following are accepted: A (Add) - add point at current cursor location. D (Delete) - delete nearest point to cursor. X (exit) - leave subroutine.

pgOlin

Interactive routine for user to enter data points by use of the cursor. Routine allows user to Add and Delete points. The points are returned in the order that they were entered (unlike pgNcurse).

Calling sequence:

pgOlin <coord> [symbol, d=-1] where coord : variable name. If coord variable does not exists it is defined. Upon return coord contains the new x and y coordinates in the form {{x-coord} {y-coord}} symbol : code number of symbol to use for marking entered points (see pgPoint). Note 1: On return from the program, cursor points are returned in the order they were entered. Routine may be (re-)called with points already defined in coord, and they will be plotted first, before editing. Note 2: User commands: the user types single-character commands after positioning the cursor: the following are accepted: A (Add) - add point at current cursor location. D (Delete) - delete nearest point to cursor. X (exit) - leave subroutine.

pgQcf

Query the current Character Font (set by routine pgScf).

Returns the current font number.

Calling sequence:

pgQcf

pgQch

Query the Character Size attribute (set by routine pgSch)

Returns the current character size.

Calling sequence:

pgQch

pgQci

Query the Color Index attribute (set by routine pgSci).

Returns the current color index (in range 0-max). This is the color index actually in use, and may differ from the color index last requested by pgSci if that index is not available on the output device.

Calling sequence:

pgQci

pgQcol

Query the range of Color Indices available for this device.

Returns the current color index range as a Tcl list. The first element is the minimum color index and the second element is the maximum.

Calling sequence:

pgQcol

pgQcr

Query the current Color Representation.

Returns the current color representation.

Calling sequence:

pgQcr

pgQfs

Query the current Fill-Area Style attribute (set by routine pgSfs).

Returns the current fill-area style:

1 => solid (default) 2 => hollow

Calling sequence:

pgQfs

pgQinf

This routine can be used to obtain miscellaneous information about the PGPLOT environment. Input is a character string defining the information required, and output is a character string containing the requested information.

The following item codes are accepted (note that the strings must match exactly, except for case, but only the first 8 characters are significant). For items marked *, PGPLOT must be in the OPEN state for the inquiry to succeed. If the inquiry is unsuccessful, either because the item code is not recognized or because the information is not available, a question mark ('?') is returned.

'version' - version of PGPLOT software in use. 'state' - status of PGPLOT ('open' if a graphics device is open for output, 'closed' otherwise). 'user' - the username associated with the calling program. 'now' - current date and time (e.g., '17-FEB-1986 10:04'). 'device' * - current PGPLOT device or file. 'file' * - current PGPLOT device or file. 'type' * - device-type of the current PGPLOT device. 'dev/type' * - current PGPLOT device and type, in a form which is acceptable as an argument for pgBegin. 'hardcopy' * - is the current device a hardcopy device? ('yes' or 'no'). 'terminal' * - is the current device the user's interactive terminal? ('yes' or 'no'). 'cursor' * - does the current device have a graphics cursor? ('yes' or 'no').

Calling sequence:

pgQinf <item> where: item : character string defining the information to be returned; see above for a list of possible values.

pgQls

Query the current Line Style attribute (set by routine pgSls).

Returns the current line-style attribute (in range 1-5).

Calling sequence:

pgQls

pgQlw

Query the current Line-Width attribute (set by routine pgSlw).

Returns the current the line-width (in range 1-21).

Calling sequence:

pgQlw

pgQvp

Inquiry routine to determine the current viewport setting. The values returned may be normalized device coordinates, inches, mm, or pixels, depending on the value of the input parameter cflag.

Returns the current

the x-coordinate of the bottom left corner of the viewport. the x-coordinate of the top right corner of the viewport. the y-coordinate of the bottom left corner of the viewport. the y-coordinate of the top right corner of the viewport.

Calling sequence:

pgQvp <units> where: units : used to specify the units of the output parameters: units = 0 : normalized device coordinates units = 1 : inches units = 2 : millimeters units = 3 : pixels Other values give an error message, and are treated as 0.

pgQwin

Inquiry routine to determine the current window setting. The values returned are world coordinates.

Returns the current

the x-coordinate of the bottom left corner of the window. the x-coordinate of the top right corner of the window. the y-coordinate of the bottom left corner of the window. the y-coordinate of the top right corner of the window.

Calling sequence:

pgQwin

pgEtxt

Some graphics terminals display text (the normal interactive dialog) on the same screen as graphics. This routine erases the text from the view surface without affecting the graphics. It does nothing on devices which do not display text on the graphics screen, and on devices which do not have this capability.

Calling sequence:

pgEtxt

pgIden

Write username, date, and time at bottom of plot.

Calling sequence:

pgIden

pgLdev

Writes a list to the terminal of all device types known to the current version of PGPLOT.

Calling sequence:

pgLdev

pgNumb

This routine converts a number into a decimal character representation. To avoid problems of floating-point roundoff, the number must be provided as an integer (mm) multiplied by a power of 10 (10**pp). The output string retains only significant digits of mm, and will be in either integer format (123), decimal format (0.0123), or exponential format (1.23x10**5). Standard escape sequences \u, \d raise the exponent and \\ is used for the multiplication sign. This routine is used by pgBox to create numeric labels for a plot. Formatting rules: (a) Decimal notation (form=1): - Trailing zeros to the right of the decimal sign are omitted - The decimal sign is omitted if there are no digits to the right of it - When the decimal sign is placed before the first digit of the number, a zero is placed before the decimal sign - The decimal sign is a period (.) - No spaces are placed between digits (ie digits are not grouped in threes as they should be) - A leading minus (-) is added if the number is negative (b) Exponential notation (form=2): - The exponent is adjusted to put just one (non-zero) digit before the decimal sign - The mantissa is formatted as in (a), unless its value is 1 in which case it and the multiplication sign are omitted - If the power of 10 is not zero and the mantissa is not zero, an exponent of the form \\10\u[-]nnn is appended, where \\ is a multiplication sign (cross), \u is an escape sequence to raise the exponent, and as many digits nnn are used as needed (c) Automatic choice (form=0): Decimal notation is used if the absolute value of the number is less than 10000 or greater than or equal to 0.01. Otherwise exponential notation is used.

Returns the formatted character string, left justified. If the length of STRING is insufficient, a single asterisk is returned.

Calling sequence:

pgNumb <mm> <pp> <form> where: mm pp : the value to be formatted is mm*10**pp. form : controls how the number is formatted: form = 0 -- use either decimal or exponential form = 1 -- use decimal notation form = 2 -- use exponential notation

pgRnd

Routine to find the smallest "round" number larger than x, a "round" number being 1, 2 or 5 times a power of 10. If X is negative, pgRnd(x) = -pgRnd(ABS(x)). eg pgRnd(8.7) = 10.0, pgRnd(-0.4) = -0.5. If x is zero, the value returned is zero. This routine is used by pgBox for choosing tick intervals.

Returns a suitable number of subdivisions for subdividing the "nice" number: 2 or 5.

Calling sequence:

pgRnd <x> where: x : the number to be rounded.

pgRnge

Chooses plotting limits xlo and xhi which encompass the data range x1 to x2.

Returns suitable values to use as the extremes of a graph axis (xlo <= x1, xhi >= x2).

Calling sequence:

pgRnge <x1> <x2> where: x1, x2 : the data range (x1 is less than x2), ie, the min and max values to be plotted.

pgPrinter

Chooses the printer command to be used by the pgDump command

Calling sequence:

pgPrinter [print_command, d: flpr -q wh6w_lwps -h bison.fnal.gov] where: print_command : the full Unix shell command to be used for printing a file.

pgDump

It invokes the xwd and xpr system services to create a PostScript bit map image of an X window. The X window to be bit mapped must be in the foreground.

Calling sequence:

pgDump [output_file] where: output_file : an optional output file to store the image instead of sending to the printer. If the printer command string is not set via the pgPrinter command and output_file is not specified then the output is directed in a system defined temporary file.