Plot lines

Plotting lines is handled by pygmt.Figure.plot.

This tutorial assumes the use of a Python notebook, such as IPython or Jupyter Notebook. To see the figures while using a Python script instead, use fig.show(method="external) to display the figure in the default PDF viewer.

To save the figure, use fig.savefig("figname.pdf") where "figname.pdf" is the desired name and file extension for the saved figure.

import pygmt

Plot lines

Create a Cartesian figure using projection parameter and set the axis scales using region (in this case, each axis is 0-10). Pass a list of x and y values to be plotted as a line.

fig = pygmt.Figure()
fig.plot(
    region=[0, 10, 0, 10],
    projection="X25c/20c",
    frame="a",
    x=[1, 8],
    y=[5, 9],
    pen="1p,black",
)
fig.show()
plot lines

Out:

<IPython.core.display.Image object>

Additional line segments can be added by including additional values for x and y.

fig = pygmt.Figure()
fig.plot(
    region=[0, 10, 0, 10],
    projection="X25c/20c",
    frame="a",
    x=[1, 6, 9],
    y=[5, 7, 4],
    pen="1p,black",
)
fig.show()
plot lines

Out:

<IPython.core.display.Image object>

To plot multiple lines, pygmt.Figure.plot needs to be used for each additional line. Parameters such as region, projection, and frame do not need to be repeated in subsequent uses.

fig = pygmt.Figure()
fig.plot(
    region=[0, 10, 0, 10],
    projection="X25c/20c",
    frame="a",
    x=[1, 6, 9],
    y=[5, 7, 4],
    pen="2p,blue",
)
fig.plot(x=[2, 4, 10], y=[3, 8, 9], pen="2p,red")
fig.show()
plot lines

Out:

<IPython.core.display.Image object>

Change line attributes

The line attributes can be set using the pen parameter. pen takes a string argument with the optional values width,color,style.

In the example below, the pen width is set to "5p", and with black as the default color and solid as the default style.

fig = pygmt.Figure()
fig.plot(
    region=[0, 10, 0, 10],
    projection="X25c/20c",
    frame="a",
    x=[1, 8],
    y=[3, 9],
    pen="5p",
)
fig.show()
plot lines

Out:

<IPython.core.display.Image object>

The line color can be set and is added after the line width to the pen argument. In the example below, the line color is set to “red”.

fig = pygmt.Figure()
fig.plot(
    region=[0, 10, 0, 10],
    projection="X25c/20c",
    frame="a",
    x=[1, 8],
    y=[3, 9],
    pen="5p,red",
)
fig.show()
plot lines

Out:

<IPython.core.display.Image object>

The line style can be set and is added after the line width or color to the pen argument. In the example below, the line color is set to dot dot dash, and the default color black is used.

fig = pygmt.Figure()
fig.plot(
    region=[0, 10, 0, 10],
    projection="X25c/20c",
    frame="a",
    x=[1, 8],
    y=[3, 9],
    pen="5p,..-",
)
fig.show()
plot lines

Out:

<IPython.core.display.Image object>

The line width, color, and style can all be set in the same pen argument. In the example below, the line width is set to 7p, the color is set to green, and the line style is dash dot dash.

For a gallery showing other pen settings, see Line styles.

fig = pygmt.Figure()
fig.plot(
    region=[0, 10, 0, 10],
    projection="X25c/20c",
    frame="a",
    x=[1, 8],
    y=[3, 9],
    pen="7p,green,-.-",
)
fig.show()
plot lines

Out:

<IPython.core.display.Image object>

Total running time of the script: ( 0 minutes 6.486 seconds)

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