plot

plot(cmd0::String="", arg1=[]; kwargs...)

Reads (x,y) pairs and plot lines, polygons, or symbols with different levels of decoration. The input can either be a file name of a file with at least two columns (x,y),but optionally more, a GMTdatset object with also two or more columns. If a symbol is selected and no symbol size given, then it 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 symbol below) must be present as last column in the input. If symbol is not used, a line connecting the data points will be drawn instead. To explicitly close polygons, use close. Select a fill with fill. If fill is set, pen will control whether the polygon outline is drawn or not. If a symbol is selected, fill and pen determines the fill and outline/no outline, respectively.

Since many options imply further data, to control symbol size and/or color for example, columns beyond 2 for plot or 3 for plot3d cannot be used to plot multiple lines at once (like Matlab does). However, that is stil possible if one uses the form plot(x, y, ...) where x is the coordinates vector or a matrix with only one column or row and y is a matrix with N columns representing the individual lines and M rows, as many as elements in x. This case, off course, looses the possibility of having extra columns with options auxiliary data. Still, another possibility to achieve this when arg1 is a MxN matrix is to use the key/val multicol=true. Automatic legends are obtained by using legend=true.

Selecting both a symbol and a pen plots a line and add the sybols at the vertex.

Parameters

• A or steps : – steps=true|steps=:meridian|:parallel|:x|:y
  By default, geographic line segments are drawn as great circle arcs. To draw them as straight lines, use the steps=true. Alternatively, use steps=:meridian to draw the line by first following a meridian, then a parallel. Or append steps=:parallel to start following a parallel, then a meridian. (This can be practical to draw a line along parallels, for example). For Cartesian data, points are simply connected, unless you use steps=:x or steps=:y to draw stair-case curves that whose first move is along x or y, respectively.

• B or axis or frame
  Set map boundary frame and axes attributes. Default is to draw and annotate left and bottom axes. More at frame

• C or color or cmap : color=cpt
  Give a CPT or specify color="color1,color2 [,color3 ,...]" or color=((r1,g1,b1),(r2,g2,b2),...) to build a linear continuous CPT from those colors automatically, where z starts at 0 and is incremented by one for each color. In this case color_n can be a [r g b] triplet, a color name, or an HTML hexadecimal color (e.g. #aabbcc ). If symbol is set, let 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 symbol is not set, then it expects the user to supply a multisegment file where each segment header contains a -Z\ val string. The val will control the color of the line or polygon (if close is set) via the CPT.

• D or shift or offset : offset=(dx,dy)|offset=dx
  Offset the plot symbol or line locations by the given amounts dx,dy [Default is no offset]. If dy is not given it is set equal to dx.

• E or error or error_bars : – error=(x|y|X|Y=true, wiskers=true, cap=width, pen=pen, colored=true, cline=true, csymbol=true)
  Draw symmetrical error bars. Use error=(x=true) and/or error=(y=true) 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,z) triplet]. If asym=true is appended then we will draw asymmetrical error bars; these requires two rather than one extra data column, with the low and high value. If upper case error=(X=true) and/or Y are 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 four more columns are expected to contain the minimum (0% quantile), the 25% quantile, the 75% quantile, and the maximum (100% quantile) values. The 25-75% box may be filled by using fill. If wiskers=true is appended the we draw a notched "box-and-whisker" symbol where the notch width reflects the uncertainty in the median. This symbol requires a 5th extra data column to contain the number of points in the distribution. The cap=width modifier sets the cap width that indicates the length of the end-cap on the error bars [7p]. Pen attributes for error bars may also be set via pen=pen. [Defaults: width = default, color = black, style = solid]. When color is used we can control how the look-up color is applied to our symbol. Add cline=true to use it to fill the symbol, while csymbol=true will just set the error pen color and turn off symbol fill. Giving colored=true will set both color items.

• F or conn or connection : – conn=(continuous=true, net|network=true, refpoint=true, ignorehdr=true, singlegroup=true, segments=true, anchor=(x,y))
  Alter the way points are connected (by specifying a scheme) and data are grouped (by specifying a method). Use one of three line connection schemes:
  continuous=true : Draw continuous line segments for each group [Default].
  refpoint=true : Draw line segments from a reference point reset for each group.
  network=true : Draw networks of line segments between all points in each group.
  Optionally, use one of four segmentation methods to define the group:
  ignore_hdr=true : Ignore all segment headers, i.e., let all points belong to a single group, and set group reference point to the very first point of the first file. single_group=true : Consider all data in each file to be a single separate group and reset the group reference point to the first point of each group. segments=true : Segment headers are honored so each segment is a group; the group reference point is reset to the first point of each incoming segment [Default]. segments_reset=true : Same as segments=true, but the group reference point is reset after each record to the previous point (this method is only available with the refpoint=true scheme). Instead of the codes ignore_hdr, single_group, segments, segments_reset you may append the coordinates of a anchor=(x,y) which will serve as a fixed external reference point for all groups.

• J or proj : proj=<parameters>
  Select map projection. Default is linear and 14 cm width. More at proj

• Jz or JZ or zscale or zsize (forplot3donly) : – zscale=scale|zsize=size
  Set z-axis scaling or or z-axis size. $zsize=size$ sets the size to the fixed value size (for example zsize=10 or zsize=4i). $zscale=scale$ sets the vertical scale to UNIT/z-unit.

• R or region or limits : limits=(xmin, xmax, ymin, ymax)|limits=(BB=(xmin, xmax, ymin, ymax),)|limits=(LLUR=(xmin, xmax, ymin, ymax),units="unit")| ...more
  Specify the region of interest. By default, the limits are computed from data extents. More at limits

• G or markerfacecolor or mc or fill
  Select color or pattern for filling of symbols or polygons [Default is no fill]. Note that plot will search for fill and pen settings in all the segment headers (when passing a GMTdaset or file of a multi-segment dataset) and let any values thus found over-ride the command line settings (but those must be provided in the terse GMT syntax). See Setting color for extend color selection (including colormap generation).

• I or shade : – shade=intens
  Use the supplied intens value (nominally in the -1 to +1 range) to modulate the fill color by simulating illumination [none]. If no intensity is provided (e.g.shade="") we will instead read intens from the first data column after the symbol parameters (if given).

• L or close : – close=(sym=true, asym=true, envelope=true, left=true, right=true, x0=x0, top=true, bot=true, y0=y0, pen=pen)
  Force closed polygons. Alternatively, add modifiers to build a polygon from a line segment. Add sym=true to build symmetrical envelope around y(x) using deviations dy(x) given in extra column 3. Add asym=true to build asymmetrical envelope around y(x) using deviations dy1(x) and dy2(x) from extra columns 3-4. Add envelope=true to build asymmetrical envelope around y(x) using bounds yl(x) and yh(x) from extra columns 3-4. Add left=true or right=true or x0=x0 to connect first and last point to anchor points at either xmin, xmax, or x0, or
  bot=true or top=true or y0=y0 to connect first and last point to anchor points at either ymin, ymax, or y0.
  Polygon may be painted (fill) and optionally outlined by adding pen=pen.

• N or noclip or no_clip : noclip=true|noclip=:r|noclip=:c
  Do NOT clip symbols that fall outside map border [Default plots points whose coordinates are strictly inside the map border only]. This option does not apply to lines and polygons which are always clipped to the map region. For periodic (360-longitude) maps we must plot all symbols twice in case they are clipped by the repeating boundary. The noclip will turn off clipping and not plot repeating symbols. Use noclip=:r to turn off clipping but retain the plotting of such repeating symbols, or use noclip=:c to retain clipping but turn off plotting of repeating symbols.

• S or symbol : – symbol=(symb=name, size=val, unit=unity) or marker|Marker|shape=name, markersize| MarkerSize|ms|size=val
  Plot symbols (including vectors, pie slices, fronts, decorated or quoted lines). If present, size is symbol size in the unit set in gmt.conf (unless c, i, or p is appended to markersize or synonym or cm, inch, point as unity when using the symbol=(symb=name,size=val,unitunity) form). If the symbol name is not given it will be read from the last column in the input data (must come from a file name or a GMTdataset); this cannot be used in conjunction with binary input (data from file). Optionally, append c, i,or p to indicate that the size information in the input data is in units of cm, inch, or point, respectively [Default is $PROJ\_LENGTH\_UNIT$]. Note: if you provide both size and symbol via the input file you must use $PROJ\_LENGTH\_UNIT$ to indicate the unit used for the symbol size or append the units to the sizes in the file. If symbol sizes are expected via the third data column then you may convert those values to suitable symbol sizes via the incol mechanism.
  You can change symbols by adding the required -S option to any of your multisegment headers (GMTdataset only). Choose between these symbol codes:
  - or x-dash size is the length of a short horizontal (x-dir) line segment.
  + or plus size is diameter of circumscribing circle.
  a or * or star size is diameter of circumscribing circle.
  c or circle size is diameter of circle.
  d or diamond size is diameter of circumscribing circle.
  e or ellipse Direction (in degrees counter-clockwise from horizontal), major_axis, and minor_axis must be found in columns 3, 4, and 5.
  E or Ellipse Same as ellipse, 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 (ellipse leaves the directions unchanged.) Furthermore, the axes lengths must be given in geographical instead of plot-distance units. An exception occurs for a linear projection in which we assume the ellipse axes are given in the same units as region. For degenerate ellipses (circles) with just the diameter given, use Ellipse-. The diameter is excepted to be given in column 3. Alternatively, append the desired diameter to E- and this fixed diameter is used instead (e.g.symbol="E-500"). For allowable geographical units, see UNITS.
  front Draw a front. See Front lines
  g or octagon size is diameter of circumscribing circle.
  h or hexagon size is diameter of circumscribing circle.
  i or v or inverted_tri size is diameter of circumscribing circle.
  j or rotated_rec Rotated rectangle. Direction (in degrees counter-clockwise from horizontal), x-dimension, and y-dimension must be found in columns 3, 4, and 5.
  J or Rotated_rec Same as rotated_rec, 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 (rotated_rec leaves the directions unchanged.) Furthermore, the dimensions must be given in geographical instead of plot-distance units. For a degenerate rectangle (square) with one dimension given, use J-. The dimension is excepted to be given in column 3. Alternatively, append the dimension diameter to J- and this fixed dimension is used instead. An exception occurs for a linear projection in which we assume the dimensions are given in the same units as region. For allowable geographical units, see UNITS.
  m or matang math angle arc, optionally with one or two arrow heads [Default is no arrow heads]. The size is the length of the vector head. Arc width is set by pen, with vector head outlines defaulting to half of arc width. The radius of the arc and its start and stop directions (in degrees counter-clockwise from horizontal) must be given in columns 3-5. See Vector Attributes for specifying other attributes.
  M or Matang Same as matang but switches to straight angle symbol if angles subtend 90 degrees exactly.
  n or pentagon size is diameter of circumscribing circle.
  p or point No size needs to be specified (1 pixel is used).
  quoted lines i.e., lines with annotations such as contours. See Quoted lines
  r or rectangle No size needs to be specified, but the x- and y-dimensions must be found in columns 3 and 4.
  R or roundrect Rounded rectangle. No size needs to be specified, but the x- and y-dimensions and corner radius must be found in columns 3, 4, and 5.
  s or square size is diameter of circumscribing circle.
  t or ^ or triangle size is diameter of circumscribing circle.
  x or cross size is diameter of circumscribing circle.
  y or y-dash (|). size is the length of a short vertical (y-dir) line segment.
  decorated i.e., lines with symbols along them. See Decorated lines
  

• W or pen=pen
  Set pen attributes for lines or the outline of symbols [Defaults: width = default, color = black, style = solid]. See Pen attributes. If the modifier pen=(cline=true) is appended then the color of the line are taken from the CPT (see cmap). If instead modifier pen=(csymbol=true) is appended then the color from the cpt file is applied to symbol fill. Use pen=(colored=true) for both effects. You can also append one or more additional line attribute modifiers: offset=val will start and stop drawing the line the given distance offsets from the end point. Append unit u from c | i | p to indicate plot distance on the map or append map distance units instead (see below); bezier=true will draw the line using a Bezier spline; vspecs will place a vector head at the ends of the lines. You can use vec_start and vec_stop to specify separate vector specs at each end [shared specs]. See the Vector Attributes for more information.

• U or time_stamp : time_stamp=true|time_stamp=(just="code", pos=(dx,dy), label="label", com=true)
  Draw GMT time stamp logo on plot. More at timestamp

• V or verbose : verbose=true|verbose=level
  Select verbosity level. More at verbose

• X or x_off or x_offset : xoff=[] | *xoff=x-shift|x_off=(shift=x-shift, mov="a|c|f|r")
  Shift plot origin. More at x_off

• Y or y_off or y_offset : yoff=[] | *yoff=y-shift|y_off=(shift=y-shift, mov="a|c|f|r")
  Shift plot origin. More at y_off

Units

For map distance unit, append unit d for arc degree, m for arc minute, and s for arc second, or e for meter [Default], f for foot, k for km, M for statute mile, n for nautical mile, and u for US survey foot. By default we compute such distances using a spherical approximation with great circles (spheric_dist=:g). You can use spheric_dist=:f to perform “Flat Earth” calculations (quicker but less accurate) or spheric_dist=:e to perform exact geodesic calculations (slower but more accurate; see $PROJ\_GEODESIC$ for method used).

Examples

Decorated curve with blue stars

    xy = gmt("gmtmath -T0/180/1 T SIND 4.5 ADD");
    lines(xy, axis=:af, pen=(1,:red), decorated=(dist=(2.5,0.25), symbol=:star,
          symbsize=1, pen=(0.5,:green), fill=:blue, dec2=true), show=true)