psxy − Plot lines, polygons, and symbols on maps


psxy files −Jparameters −Rwest/east/south/north[r] [ −A ] [ −Btickinfo ] [ −Ccptfile ] [ −Ddx/dy ] [ −E[x|y|X|Y][cap][/pen] ] [ −Gfill ] [ −H[nrec] ] [ −K ] [ −L ] [ −N ] [ −M[flag] ] [ −O ] [ −P ] [ −S[symbol][size] ] [ −U[/dx/dy/][label] ] [ −V ] [ −W[pen] ] [ −Xx-shift ] [ −Yy-shift ] [ −: ] [ −ccopies ] [ −bi[s][n] ] [ −f[i|o]colinfo ]


psxy reads (x,y) pairs from files [or standard input] and generates PostScript code that will plot lines, polygons, or symbols at those locations on a map. If a symbol is selected and no symbol size given, then psxy will interpret the third column of the input data as symbol size. Symbols whose size is <= 0 are skipped. If no symbols are specified then the symbol code (see −S below) must be present as last column in the input. Multiple segment files may be plotted using the −M option. If −S is not selected, a line connecting the data points will be drawn instead. To explicitly close polygons, use −L. Select a shade with −G. If −G is set, −W will control whether the polygon outline is drawn or not. If a symbol is selected, −G and −W determines the fill color and outline/no outline, respectively. The PostScript code is written to standard output.


List one or more file-names. If no files are given, psxy will read standard input.


Selects the map projection. Scale is UNIT/degree, 1:xxxxx, or width in UNIT (upper case modifier). UNIT is cm, inch, or m, depending on the MEASURE_UNIT setting in .gmtdefaults4, but this can be overridden on the command line by appending c, i, or m to the scale/width value. For map height, max dimension, or min dimension, append h, +, or - to the width, respectively.

More details can be found in the psbasemap man pages.


−Jclon0/lat0/scale (Cassini)
lon0/scale (Miller)
scale (Mercator - Greenwich and Equator as origin)
lon0/lat0/scale (Mercator - Give meridian and standard parallel)
lon0/lat0/azimuth/scale (Oblique Mercator - point and azimuth)
lon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
lon0/lat0/lonp/latp/scale (Oblique Mercator - point and pole)
lon0/scale (Equidistant Cylindrical Projection (Plate Carree))
lon0/scale (TM - Transverse Mercator, with Equator as y = 0)
lon0/lat0/scale (TM - Transverse Mercator, set origin)
zone/scale (UTM - Universal Transverse Mercator)
lon0/lats/scale (Basic Cylindrical Projection)


−Jalon0/lat0/scale (Lambert)
lon0/lat0/scale (Equidistant)
lon0/lat0/horizon/scale (Gnomonic)
lon0/lat0/scale (Orthographic)
lon0/lat0/[slat/]scale (General Stereographic)


−Jblon0/lat0/lat1/lat2/scale (Albers)
lon0/lat0/lat1/lat2/scale (Equidistant)
lon0/lat0/lat1/lat2/scale (Lambert)


−Jhlon0/scale (Hammer)
lon0/scale (Sinusoidal)
[f|s]lon0/scale (Eckert IV (f) and VI (s))
lon0/scale (Robinson)
lon0/scale (Winkel Tripel)
lon0/scale (Van der Grinten)
lon0/scale (Mollweide)


−Jp[a]scale[/origin][r] (Polar coordinates (theta,r))
x-scale[d|l|ppow|t|T][/y-scale[d|l|ppow|t|T]] (Linear, log, and power scaling)


xmin, xmax, ymin, and ymax specify the Region of interest. For geographic regions, these limits correspond to west, east, south, and north and you may specify them in decimal degrees or in [+-]dd:mm[][W|E|S|N] format. Append r if lower left and upper right map coordinates are given instead of wesn. The two shorthands −Rg −Rd stand for global domain (0/360 or -180/+180 in longitude respectively, with -90/+90 in latitude). For calendar time coordinates you may either give relative time (relative to the selected TIME_EPOCH and in the selected TIME_UNIT; append t to −JX|x), or absolute time of the form [date]T[clock] (append T to −JX|x). At least one of date and clock must be present; the T is always required. The date string must be of the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or yyyy[-Www[-d]] (ISO week calendar), while the clock string must be of the form hh:mm:ss[.xxx]. The use of delimiters and their type and positions must be as indicated (however, input/output and plotting formats are flexible).


No space between the option flag and the associated arguments.


Suppress drawing line segments as great circle Arcs. [Default draws great circle arcs].


Sets map boundary annotation and tickmark intervals; see the psbasemap man page for all the details.


Give a color palette file. When used with −S, lets symbol fill color be determined by the z-value in the third column. Additional fields are shifted over by one column (optional size would be 4th rather than 3rd field, etc.). If −S is not set, psxy expects the user to supply a multisegment line or polygon file (requires −M) and will look for −Zval strings in each multisegment header. The val will control the color of either the line or polygon (if −L is set) via the cpt file.


Offset the plot symbol locations by the given amounts dx/dy [Default is no offset]. Only applies to symbols.


Draw error bars. Append x and/or y to indicate which bars you want to draw (Default is both x and y). The x and/or y errors must be stored in the columns after the (x,y) pair [or (x,y,size) triplet]. The cap parameter indicates the length of the end-cap on the error bars [0.25c (or 0.1i)]. Pen attributes for error bars may also be set. [Defaults: width = 1, color = black, texture = solid]. If upper case X and/or Y is used we will instead draw "box-and-whisker" (or "stem-and-leaf") symbols. The x (or y) coordinate is then taken as the median value, and 4 more columns are expected to contain the minimum (0% quartile), the 25% quartile, the 75% quartile, and the maximum (100% quartile) values. The 25-75% box may be filled by using −G.


Select color for filling of symbols or select color or pattern for filling of polygons [Default is no fill].

Specify the grey shade (0−255) or color (r/g/b, each in range 0−255; h-s-v, ranges 0−360, 0−1, 0−1; or c/m/y/k, each in range 0−100%; or valid color name). Alternatively, specify −Gpdpi/pattern, where pattern gives the number of the built-in pattern (1-90) or the name of a Sun 1-, 8-, or 24-bit raster file. The dpi sets the resolution of the image. For 1-bit rasters: use −GP for inverse video, or append :Fcolor[B[color]] to specify fore- and background colors (use color = - for transparency). See GMT Cookbook & Technical Reference Appendix E for information on individual patterns.
Note when −M is chosen, psxy will search for −G and −W strings in all the subheaders and let any values thus found over-ride the command line settings.


Input file(s) has Header record(s). Number of header records can be changed by editing your .gmtdefaults4 file. If used, GMT default is 1 header record. Use −Hi if only input data should have header records [Default will write out header records if the input data have them].


More PostScript code will be appended later [Default terminates the plot system].


Force closed polygons: connect the endpoints of the line-segment(s) and draw polygons. Also, in concert with −C, −M, and −Z settings in the headers will use the implied color for polygon fill [Default is polygon pen color].


Multiple segment file. Segments are separated by a record whose first character is flag. [Default is ’>’].


Do NOT skip symbols that fall outside map border [Default plots points inside border only]. The option does not apply to lines and polygons which are always clipped to the map region.


Selects Overlay plot mode [Default initializes a new plot system].


Selects Portrait plotting mode [GMT Default is Landscape, see gmtdefaults to change this].


Plot symbols. If present, size is symbol size in the unit set in .gmtdefaults4 (unless c, i, m, or p is appended). If the symbol code (see below) is not given it will be read from the last column in the input data; this cannot be used in conjunction with −b. Optionally, append c, i, m, p to indicate that the size information in the input data is in units of cm, inch, meter, or point, respectively. [Default is MEASURE_UNIT]. Note: if you give both size and symbol via the input file you must use MEASURE_UNIT to indicate the units used for the symbol size.

The uppercase symbols A, C, D, G, H, I, N, S, T are normalized to have the same area as a circle with diameter size, while the corresponding lowercase symbols all are circumscribed by the circle. Choose between these symbol codes:


x-dash. size is the length of a short horizontal line segment.


star. size is diameter of circumscribing circle.


bar extending from base to y. size is bar width. Append u if size is in x-units [Default is plot-distance units]. By default, base = 0. Append bbase to change this value.


circle. size is diameter of circle.


diamond. size is diameter of circumscribing circle.


ellipse. Direction (in degrees counter-clockwise from horizontal), major_axis, and minor_axis must be found in columns 3, 4, and 5.


Same as −Se, except azimuth (in degrees east of north) should be given instead of direction. The azimuth will be mapped into an angle based on the chosen map projection (−Se leaves the directions unchanged.) Furthermore, the axes lengths must be given in km instead of plot-distance units. An exception occurs for a linear projection if which we assume the ellipse axes are given in the same units as −R.


front. −Sfgap/size[dir][type][:offset]. Supply distance gap between symbols and symbol size. If gap is negative, it is interpreted to mean the number of symbols along the front instead. Append dir to plot symbols on the left or right side of the front [Default is centered]. Append type to specify which symbol to plot: box, circle, fault, slip, or triangle. [Default is fault]. Slip means left-lateral or right-lateral strike-slip arrows (centered is not an option). Append :offset to offset the first symbol from the beginning of the front by that amount [Default is 0].


hexagon. size is diameter of circumscribing circle.


inverted triangle. size is diameter of circumscribing circle.


kustom symbol. Append <name>/size, and we will look for a definition file called <name>.def in (1) the current directory or (2) in $GMTHOME/share/custom. The symbol as defined in that file is of size 1.0 by default; the appended size will scale symbol accordingly. Users may add their own custom *.def files; see CUSTOM SYMBOLS below.


letter or text string (less than 64 characters). Give size, and append /string after the size. Note that the size is only approximate; no individual scaling is done for different characters. Remember to escape special characters like *. Optionally, you may append %font to select a particular font [Default is ANNOT_FONT_PRIMARY].


octagon. size is diameter of circumscribing circle.


pentagon. size is diameter of circumscribing circle.


point. No size needs to be specified (1 pixel is used).


quoted line, i.e., lines with annotations such as contours. Append [d|f|n|l|x]info[:labelinfo]. The required argument controls the placement of labels along the quoted lines. Choose among five controlling algorithms:

ddist[c|i|m|p] or Ddist[d|e|k|m|n]

For lower case d, give distances between labels on the plot in your preferred measurement unit c (cm), i (inch), m (meter), or p (points), while for upper case D, specify distances in map units and append the unit; choose among e (m), k (km), m (mile), n (nautical mile), or d (spherical degree). [Default is 10c or 4i].


Reads the ascii file ffile.d and places labels at locations in the file that matches locations along the quoted lines. Inexact mathces and points outside the region are skipped.


Give start and stop coordinates for one or more comma-separated straight line segments. Labels will be placed where these lines intersect the quoted lines. The format of each line specification is start/stop, where start and stop are either a specified point lon/lat or a 2-character XY key that uses the justification format employed in pstext to indicate a point on the map, given as [LCR][BMT]. L will interpret the point pairs as defining great circles [Default is straight line].


Specifies the number of equidistant labels for quoted lines line [1]. Upper case N starts labeling exactly at the start of the line [Default centers them along the line]. N-1 places one justified label at start, while N+1 places one justified label at the end of quoted lines. Optionally, append /min_dist[c|i|m|p] to enforce that a minimum distance separation between successive labels is enforced.


Reads the multi-segment file xfile.d and places labels at the intersections between the quoted lines and the lines inxfile.d. X will resample the lines first along great-circle arcs.

The optional labelinfo controls the specifics of the label formatting and consists of a concatenated string made up of any of the following control arguments:


For annotations at a fixed angle, +an for line-normal, or +ap for line-parallel [Default].


Sets the clearance between label and optional text box. Append c|i|m|p to specify the unit or % to indicate a percentage of the label font size [15%].


Sets the desired font [Default



Selects opaque text boxes [Default is transparent]; optionally specify the color [Default is PAGE_COLOR].


Sets label justification [Default is CM].


Sets color of text labels [Default is COLOR_BACKGROUND].


Sets the constant label text.


Sets the label text according to the specified flag:


Take the label from the current multisegment header (first scan for an embedded −Llabel option, if not use the first word following the segment flag).


Take the Cartesian plot distances along the line as the label; append c|i|m|p as the unit [Default is MEASURE_UNIT].


Calculate actual map distances; append d|e|k|m|n as the unit [Default is d(egrees), unless label placement was based on map distances along the lines in which case we use the same unit specified for that algorithm]. Requires a map projection to be used.


Use text after the 2nd column in the fixed label location file as the label. Requires the fixed label location setting.


As +Lh but use the headers in the xfile.d instead. Requires the crossing file option.


Selects rounded rectangular text box [Default is

rectangular]. Not applicable for curved text (+v) and only makes sense for opaque text boxes.


Draws the outline of text boxsets [Default is no outline]; optionally specify pen for outline [Default is width = 0.25p, color = black, texture = solid]. pen is a comma delimetered list of width, color and texture, each of which is optional. width can be indicated as a measure (points, centimeters, inches) or as faint, thin[er|est], thick[er|est], fat[er|est], or obese. color specifies a grey shade (0−255) or color (r/g/b, each in range 0−255; h-s-v, ranges 0−360, 0−1, 0−1; or c/m/y/k, each in range 0−100%; or valid color name). texture is a combination of dashes ‘-’ and dots ‘.’.


Will not place labels where the line’s radius of curvature is less than min_rad [Default is 0].


Sets the desired font size in points [Default is 9].


Appends unit to all line labels. If unit starts with a leading hypen (-) then there will be no space between label value and the unit. [Default is no unit].


Specifies curved labels following the path [Default is straight labels].


Specifies how many (x, y) points will be used to estimate label angles [Default is 10].


Prepends prefix to all line labels. If prefix starts with a leading hypen (-) then there will be no space between label value and the prefix. [Default is no prefix].


rectangle. No size needs to be specified, but the x- and y-dimensions must be found in columns 3 and 4.


square. size is diameter of circumscribing circle.


triangle. size is diameter of circumscribing circle.


vector. Direction (in degrees counter-clockwise from horizontal) and length must be found in columns 3 and 4. size, if present, will be interpreted as arrowwidth/headlength/headwidth [Default is 0.075c/0.3c/0.25c (or 0.03i/0.12i/0.1i)]. By default arrow attributes remains invariant to the length of the arrow. To have the size of the vector scale down with decreasing size, append nnorm, where vectors shorter than norm will have their attributes scaled by length/norm. To center vector on balance point, use −Svb; to align point with the vector head, use −Svh; to align point with the vector tail, use −Svt [Default]. To give the head point’s coordinates instead of direction and length, use −Svs. Upper case B, H, T, S will draw a double-headed vector [Default is single head].


Same as −Sv, except azimuth (in degrees east of north) should be given instead of direction. The azimuth will be mapped into an angle based on the chosen map projection (−Sv leaves the directions unchanged.)


pie wedge. Start and stop directions (in degrees counter-clockwise from horizontal) for pie slice must be found in columns 3 and 4.


cross. size is diameter of circumscribing circle.


y-dash. size is the length of a short vertical line segment.


Draw Unix System time stamp on plot. User may specify where the lower left corner of the stamp should fall on the page relative to lower left corner of plot. Optionally, append a label, or c (which will plot the command string.). The GMT parameters UNIX_TIME and UNIX_TIME_POS can affect the appearance; see the gmtdefaults man page for details.


Selects verbose mode, which will send progress reports to stderr [Default runs "silently"].


Set pen attributes for lines or the outline of symbols. [Defaults: width = 1, color = black, texture = solid]. pen is a comma delimetered list of width, color and texture, each of which is optional. width can be indicated as a measure (points, centimeters, inches) or as faint, thin[er|est], thick[er|est], fat[er|est], or obese. color specifies a grey shade (0−255) or color (r/g/b, each in range 0−255; h-s-v, ranges 0−360, 0−1, 0−1; or c/m/y/k, each in range 0−100%; or valid color name). texture is a combination of dashes ‘-’ and dots ‘.’.

−X −Y

Shift origin of plot by (x-shift,y-shift). Prepend a for absolute coordinates; the default (r) will reset plot origin. Give c to center plot using current page size.


Toggles between (longitude,latitude) and (latitude,longitude) input and/or output. [Default is (longitude,latitude)]. Append i to select input only or o to select output only. [Default affects both].


Selects binary input. Append s for single precision [Default is double]. Uppercase S (or D) will force byte-swapping. Append n for the number of columns in the binary file(s). [Default is the required number of columns given the chosen settings].


Specifies the number of plot copies. [Default is 1].


Special formatting of input and output columns (time or geographical data). Specify i(nput) or o(utput) [Default is both input and output]. Give one or more columns (or column ranges) separated by commas. Append T (Absolute calendar time), t (time relative to chosen TIME_EPOCH), x (longitude), y (latitude), or f (floating point) to each column or column range item. Shorthand −f[i|o]g means −f[i|o]0x,1y (geographic coordinates).


To plot solid red circles (diameter = 0.25 cm) at the positions listed in the file DSDP.xy on a Mercator map at 5 cm/degree of the area 150E to 154E, 18N to 23N, with tickmarks every 1 degree and gridlines every 15 minutes, use

psxy DSDP.xy −R150/154/18/23 −Jm5c −Sc0.25c −Gred −B1g15m | lpr

To plot the xyz values in the file quakes.xyzm as circles with size given by the magnitude in the 4th column and color based on the depth in the third using the color palette cpt on a linear map, use

psxy quakes.xyzm −R0/1000/0/1000 −JX6i −Sc −Ccpt −B200 >

To plot the file trench.xy on a Mercator map, with white triangles with sides 0.25 inch on the left side of the line, spaced every 0.8 inch, use

psxy trench.xy −R150/200/20/50 −Jm0.15i −Sf0.8i/0.1ilt −Gwhite −W −B10 | lpr br

To plot the data in the file misc.d as symbols determined by the code in the last column, and with size given by the magnitude in the 4th column, and color based on the third column via the color palette cpt on a linear map, use

psxy misc.d −R0/100/-50/100 −JX6i −S −Ccpt −B20 >


The −N option does not adjust the BoundingBox information so you may have to post-process the PostScript outout with epstool or ps2epsi to obtain a correct BoundingBox.
cannot handle filling of polygons that contain the south or north pole. For such a polygon, make a copy and split it into two and make each explicitly contain the polar point. The two polygons will combine to give the desired effect when filled; to draw outline use the original polygon.


psxy and psxyz allows users to define and plot their own custom symbols. This is done by encoding the symbol using a simple plotting code described below. Put all the plotting codes for your new symbol in a file whose extension must be .def; you may then address the symbol without giving the extension (e.g., the symbol file tsunami.def is used by specifying −Sktsunami/size. The definition file can contain any number of plot code records, as well as blank lines and comment lines (starting with #). psxy and psxyz will look for the definition files in (1) the current directory and (2) the $GMTHOME/share/custom, in that order. Freeform polygons (made up of straight line segments and arcs of circles) can be designed - these polygons can be painted and filled with a pattern. Other standard geometric symbols can also be used. With the exception of the circle, these can only be painted, not filled with a pattern (use the freeform polygons to include a triangle that can be filled with a pattern). Generate freeform polygons by starting with an anchor point (append [ −Wpen ] and [ −Gfill ] to indicate pen and fill attributes):
x0 y0
and draw a straight line from the current point to the next point with
x y
or add an arc by using
xc yc r dir1 dir2
When a record other than the D or A is encountered, the polygon is closed and considered complete. The optional pen and fill setting hardwires particular values for this feature. If not present the polygon’s characteristics are determined by the command line settings for pen and fill. To deactivate fill or outline for any given polygon, give −G− or −W−. To add other geometric shapes to your custom symbol, add any number of the following plot code records (each accepts the optional [ −Wpen ] and [ −Gfill ] at the end):

star: x y size a
circle: x y size c
cross: x y size x
diamond: x y size d
ellipse: x y dir major minor e
hexagon: x y size h
invtriangle: x y size i
letter: x y size string l
octagon: x y size g
pentagon: x y size n
rect: x y xwidth ywidth r
square: x y size s
triangle: x y size t
wedge: x y radius dir1 dir2 w

When designing your symbol, the x, y and other dimensions are relative to a symbol of size 1, and all the dimensions will be scaled by the actual symbol size chosen at run-time. To design a symbol, make a grid paper with psbasemap −R-0.5/0.5/-0.5/0.5 −JX4i −Ba0.1g0.05 −P > and draw your symbol, centering it on (0,0). For examples of symbols, see the set supplied with GMT in $GMTHOME/share/custom.


GMT(l), psbasemap(l), psxyz(l)