Add a gallery example for plotting Cartesian, circular and geographic vectors

examples/gallery/plot/vectors.py

@@ -0,0 +1,59 @@
+"""
+Vectors
+------
+
+The :meth:`pygmt.Figure.plot` method can plot cartesian, circular, and geographic vectors.
+The `style` parameter controls vector attributes as in GMT6
+
+"""
+import numpy as np
+import pygmt
+
+# Create a plot with 15x15 cm basemap, Mercator projection (M) over the continental US
+region = [-127, -64, 24, 53]
+fig = pygmt.Figure()
+fig.coast(region=region, projection="M15c", B="10.0", N="1", A="4000", W="0.25p,black")
+
+
+# plot math angle arcs with different radii
+x = -110
+y = 37
+startdir = 90
+stopdir = 180
+radius = 1.8
+pen = "1.5p,black"
+arcstyles = np.repeat("m0.5c+ea", 7)
+for arcstyle in arcstyles:
+    data = np.array([[x, y, radius, startdir, stopdir]])
+    fig.plot(data=data, style=arcstyle, color="red3", pen=pen)
+    stopdir += 40
+    radius -= 0.2
+fig.text(text="CIRCULAR", x=-112, y=44.2, font="13p,Helvetica-Bold,black", fill="white")
+
+
+# plot cartesian vectors with different lengths
+x = np.linspace(-100, -100, 12)  # x vector coordinates
+y = np.linspace(33, 42.5, 12)  # y vector coordinates
+xvec = np.linspace(1, 5, 12)  # dx vector data
+yvec = np.zeros(np.shape(y))  # dy vector data
+style = "v0.2+e+a40+gred+h0+p1p,red+z0.35"
+pen = "1.0p,red"
+fig.plot(x=x, y=y, style=style, pen=pen, direction=[xvec, yvec])
+fig.text(text="CARTESIAN", x=-95, y=44.2, font="13p,Helvetica-Bold,red", fill="white")
+
+
+# plot geographic vectors using endpoints
+NYC = [-74.0060, 40.7128]
+CHI = [-87.6298, 41.8781]
+SEA = [-122.3321, 47.6062]
+NO = [-90.0715, 29.9511]
+style = "=0.5+e+a30+gblue+h0.5+p1p,blue+s"  # = for geographic coordinates, +s for coord end points
+pen = "1.0p,blue"
+data = np.array([[NYC[0], NYC[1], CHI[0], CHI[1]]])
+data = np.vstack((data, np.array([[NYC[0], NYC[1], SEA[0], SEA[1]]])))
+data = np.vstack((data, np.array([[NYC[0], NYC[1], NO[0], NO[1]]])))
+fig.plot(data=data, style=style, pen=pen)
+fig.text(
+    text="GEOGRAPHIC", x=-74.5, y=44.2, font="13p,Helvetica-Bold,blue", fill="white"
+)
+fig.show()