Add missing aliases to pygmt.grdgradient

pygmt/src/grdgradient.py

@@ -21,7 +21,10 @@
     D="direction",
     E="radiance",
     G="outgrid",
+    N="normalize",
+    Q="norm_control",
     R="region",
+    S="slope_file",
     V="verbose",
     n="interpolation",
 )
@@ -89,6 +92,40 @@ def grdgradient(grid, **kwargs):
         algorithm; in this case the *azim* and *elev* are hardwired to 315
         and 45 degrees. This means that even if you provide other values
         they will be ignored.)
+    normalize : str or bool
+        [**e**\|\ **t**][*amp*][**+a**\ *ambient*][**+s**\ *sigma*]
+        [**+o**\ *offset*].
+        The actual gradients *g* are offset and scaled to produce normalized
+        gradients *gn* with a
+        maximum output magnitude of *amp*. If *amp* is not given, default
+        *amp* = 1. If *offset* is not given, it is set to the average of
+        *g*. **True** yields *gn* = *amp* \* (*g* - *offset*)/max(abs(\ *g* -
+        *offset*)). **e** normalizes using a cumulative Laplace
+        distribution yielding *gn* = *amp* \* (1.0 -
+        exp(sqrt(2) \* (*g* - *offset*)/ *sigma*)), where
+        *sigma* is estimated using the L1 norm of (*g* - *offset*) if it is
+        not given. **t** normalizes using a cumulative Cauchy distribution
+        yielding *gn* = (2 \* *amp* / PI) \* atan( (*g* - *offset*)/
+        *sigma*) where *sigma* is estimated using the L2 norm of (*g* -
+        *offset*) if it is not given. To use *offset* and/or *sigma* from a
+        previous calculation, leave out the argument to the modifier(s) and
+        see `norm_control` for usage.  As a final option, you may add
+        **+a**\ *ambient* to add *ambient* to all nodes after gradient
+        calculations are completed.
+    norm_control : str
+        **c**\|\ **r**\|\ **R**
+        Controls how normalization via `normalize` is carried out.  When
+        multiple  grids should be normalized the same way (i.e., with the same
+        *offset*  and/or *sigma*),
+        we must pass these values via `normalize`.  However, this is
+        inconvenient if we compute these values from a grid.  Use **c** to
+        save  the results  of *offset* and *sigma* to a statistics file; if
+        grid output is not  needed for this run then do not specify `outgrid`.
+        For  subsequent runs,  just use **r** to read these values.  Using
+        **R**  will read then delete the statistics file.
+    slope_file : str
+        Name of output grid file with scalar magnitudes of gradient vectors.
+        Requires `direction` but makes `outgrid` optional.
     {R}
     {V}
     {n}
@@ -103,6 +140,10 @@ def grdgradient(grid, **kwargs):
           ``outgrid``)
     """
     with GMTTempFile(suffix=".nc") as tmpfile:
+        if "Q" in kwargs and "N" not in kwargs:
+            raise GMTInvalidInput(
+                """Must specify normalize if norm_control is specified."""
+            )
         if not args_in_kwargs(args=["A", "D", "E"], kwargs=kwargs):
             raise GMTInvalidInput(
                 """At least one of the following parameters must be specified: