grass.script: Fix sign and hemisphere handling in float_or_dms

python/grass/script/tests/utils_test.py

@@ -26,6 +26,32 @@ def test_unrecognized_separator():
     assert gs.separator("apple") == "apple"
 
 
+@pytest.mark.parametrize(
+    ("dms", "expected"),
+    [
+        ("26:45:30", 26.758333333333333),
+        ("+26:45:30", 26.758333333333333),
+        ("-26:45:30", -26.758333333333333),
+        ("26:45:30N", 26.758333333333333),
+        ("26:45:30E", 26.758333333333333),
+        ("26:45:30S", -26.758333333333333),
+        ("26:45:30W", -26.758333333333333),
+        ("-0:30:0", -0.5),
+        ("12.5", 12.5),
+        ("-12.5", -12.5),
+    ],
+)
+def test_float_or_dms(dms, expected):
+    """Check that sign and hemisphere letters are applied to the whole value"""
+    assert gs.float_or_dms(dms) == pytest.approx(expected)
+
+
+def test_float_or_dms_empty():
+    """Check that an empty string is reported as an invalid value"""
+    with pytest.raises(ValueError, match="could not convert"):
+        gs.float_or_dms("")
+
+
 def test_KeyValue_keys():
     """Check that KeyValue class works like a Dict"""
     kv = gs.KeyValue()

python/grass/script/utils.py

@@ -50,13 +50,26 @@ def float_or_dms(s) -> float:
     >>> round(float_or_dms("26:0:0.1"), 5)
     26.00003
 
+    A leading minus sign or a trailing S or W hemisphere letter
+    makes the result negative:
+
+    >>> round(float_or_dms("-26:45:30"), 5)
+    -26.75833
+    >>> round(float_or_dms("26:45:30S"), 5)
+    -26.75833
+
     :param s: DMS value
 
     :return: float value
     """
-    if s[-1] in {"E", "W", "N", "S"}:
+    negative = s[-1:] in {"S", "W"}
+    if s[-1:] in {"E", "W", "N", "S"}:
         s = s[:-1]
-    return sum(float(x) / 60**n for (n, x) in enumerate(s.split(":")))
+    if s[:1] in {"-", "+"}:
+        negative = negative or s[0] == "-"
+        s = s[1:]
+    value = sum(float(x) / 60**n for (n, x) in enumerate(s.split(":")))
+    return -value if negative else value
 
 
 def separator(sep: str) -> str:

scripts/r.import/r.import.py

@@ -353,18 +353,10 @@ def main():
                 w = srcregion["w"]
             except ValueError:  # import into latlong, expect 53:39:06.894826N
                 srcregion = gs.parse_key_val(tgtextents, vsep=" ")
-                n = gs.float_or_dms(srcregion["n"][:-1]) * (
-                    -1 if srcregion["n"][-1] == "S" else 1
-                )
-                s = gs.float_or_dms(srcregion["s"][:-1]) * (
-                    -1 if srcregion["s"][-1] == "S" else 1
-                )
-                e = gs.float_or_dms(srcregion["e"][:-1]) * (
-                    -1 if srcregion["e"][-1] == "W" else 1
-                )
-                w = gs.float_or_dms(srcregion["w"][:-1]) * (
-                    -1 if srcregion["w"][-1] == "W" else 1
-                )
+                n = gs.float_or_dms(srcregion["n"])
+                s = gs.float_or_dms(srcregion["s"])
+                e = gs.float_or_dms(srcregion["e"])
+                w = gs.float_or_dms(srcregion["w"])
 
             env["GRASS_REGION"] = gs.region_env(n=n, s=s, e=e, w=w)