Force the default position for image

Author: seisman

pygmt/src/image.py

@@ -19,19 +19,19 @@ def image(  # noqa: PLR0913
     self,
     imagefile: PathLike,
     position: Position | None = None,
-    height: float | str | None = None,
     width: float | str | None = None,
-    replicate: int | Sequence[int] | None = None,
+    height: float | str | None = None,
     dpi: float | str | None = None,
+    replicate: int | Sequence[int] | None = None,
     box: Box | bool = False,
     monochrome: bool = False,
     projection: str | None = None,
     region: Sequence[float | str] | str | None = None,
     verbose: Literal["quiet", "error", "warning", "timing", "info", "compat", "debug"]
     | bool = False,
     panel: int | Sequence[int] | bool = False,
-    transparency: float | None = None,
     perspective: float | Sequence[float] | str | bool = False,
+    transparency: float | None = None,
     **kwargs,
 ):
     r"""
@@ -70,8 +70,8 @@ def image(  # noqa: PLR0913
         contain an appropriate BoundingBox. A raster file can have a depth of 1, 8, 24,
         or 32 bits and is read via GDAL.
     position
-        Specify the position of the image on the plot. See
-        :class:`pygmt.params.Position` for details.
+        Position of the image on the plot. Pass a :class:`pygmt.params.Position` object
+        to specify the location, anchor, and offset. [Default is at the plot origin.]
     width
     height
         Width (and height) of the image in plot coordinates (inches, cm, etc.). If
@@ -124,6 +124,14 @@ def image(  # noqa: PLR0913
         )
         raise GMTInvalidInput(msg)
 
+    # width is required when only height is given.
+    if width is None and height is not None:
+        width = 0
+
+    # Default position at the plot origin.
+    if position is None:
+        position = Position((0, 0), cstype="plotcoords")
+
     aliasdict = AliasSystem(
         D=[
             Alias(position, name="position"),