Add enums GridFormat for GMT grid format ID (#3449)

Co-authored-by: Wei Ji <[email protected]>

pygmt/enums.py

@@ -0,0 +1,39 @@
+"""
+Enumerations for PyGMT.
+"""
+
+from enum import IntEnum
+
+
+class GridFormat(IntEnum):
+    """
+    Enum for the GMT grid format ID.
+
+    These enums are defined in 'gmt_grdio.h'.
+    """
+
+    UNKNOWN = 0  #: Unknown grid format
+    BF = 1  #: GMT native, C-binary format (32-bit float)
+    BS = 2  #: GMT native, C-binary format (16-bit integer)
+    RB = 3  #: SUN rasterfile format (8-bit standard)
+    BB = 4  #: GMT native, C-binary format (8-bit integer)
+    BM = 5  #: GMT native, C-binary format (bit-mask)
+    SF = 6  #: Golden Software Surfer format 6 (32-bit float)
+    CB = 7  #: GMT netCDF format (8-bit integer, deprecated)
+    CS = 8  #: GMT netCDF format (16-bit integer, deprecated)
+    CI = 9  #: GMT netCDF format (32-bit integer, deprecated)
+    CF = 10  #: GMT netCDF format (32-bit float, deprecated)
+    CD = 11  #: GMT netCDF format (64-bit float, deprecated)
+    RF = 12  #: GEODAS grid format GRD98 (NGDC)
+    BI = 13  #: GMT native, C-binary format (32-bit integer)
+    BD = 14  #: GMT native, C-binary format (64-bit float)
+    NB = 15  #: GMT netCDF format (8-bit integer)
+    NS = 16  #: GMT netCDF format (16-bit integer)
+    NI = 17  #: GMT netCDF format (32-bit integer)
+    NF = 18  #: GMT netCDF format (32-bit float)
+    ND = 19  #: GMT netCDF format (64-bit float)
+    SD = 20  #: Golden Software Surfer format 7 (64-bit float, read-only)
+    AF = 21  #: Atlantic Geoscience Center format AGC (32-bit float)
+    GD = 22  #: Import through GDAL
+    EI = 23  #: ESRI Arc/Info ASCII Grid Interchange format (ASCII integer)
+    EF = 24  #: ESRI Arc/Info ASCII Grid Interchange format (ASCII float)