Allow passing in scalar number to x and y in plot

pygmt/base_plotting.py

@@ -361,8 +361,8 @@ def plot(self, x=None, y=None, data=None, sizes=None, direction=None, **kwargs):
 
         Parameters
         ----------
-        x, y : 1d arrays
-            Arrays of x and y coordinates of the data points.
+        x, y : float or 1d arrays
+            The x and y coordinates, or arrays of x and y coordinates of the data points
         data : str or 2d array
             Either a data file name or a 2d numpy array with the tabular data.
             Use option *columns* (i) to choose which columns are x, y, color,
@@ -426,7 +426,9 @@ def plot(self, x=None, y=None, data=None, sizes=None, direction=None, **kwargs):
             elif kind == "matrix":
                 file_context = lib.virtualfile_from_matrix(data)
             elif kind == "vectors":
-                file_context = lib.virtualfile_from_vectors(x, y, *extra_arrays)
+                file_context = lib.virtualfile_from_vectors(
+                    np.atleast_1d(x), np.atleast_1d(y), *extra_arrays
+                )
 
             with file_context as fname:
                 arg_str = " ".join([fname, build_arg_string(kwargs)])

pygmt/tests/test_plot.py

@@ -256,3 +256,14 @@ def test_plot_vectors():
         frame="af",
     )
     return fig
+
+
+@pytest.mark.mpl_image_compare
+def test_plot_scalar_xy():
+    "Plot symbols given scalar x, y coordinates"
+    fig = Figure()
+    fig.basemap(region=[-2, 2, -2, 2], frame=True)
+    fig.plot(x=-1.5, y=1.5, style="c1c")
+    fig.plot(x=0, y=0, style="t1c")
+    fig.plot(x=1.5, y=-1.5, style="s1c")
+    return fig