BUG: Apply more robust string converts in loadtxt

The original dtype converters for bytes and str
did not account for converting objects of str or
bytes dtype respectively. Replace the original
converters with those from numpy.compat, which
are much more robust.

Closes gh-8033.

2 files changed, 11 insertions, 2 deletions

diff --git a/numpy/lib/npyio.py b/numpy/lib/npyio.py
index 05010a2d0..13eb5cefc 100644
--- a/numpy/lib/npyio.py
+++ b/numpy/lib/npyio.py
@@ -702,9 +702,9 @@ def _getconv(dtype):
     elif issubclass(typ, np.complex):
         return lambda x: complex(asstr(x))
     elif issubclass(typ, np.bytes_):
-        return bytes
+        return asbytes
     else:
-        return str
+        return asstr
 
 
 def loadtxt(fname, dtype=float, comments='#', delimiter=None,
diff --git a/numpy/lib/tests/test_io.py b/numpy/lib/tests/test_io.py
index 333891d46..61c9c0636 100644
--- a/numpy/lib/tests/test_io.py
+++ b/numpy/lib/tests/test_io.py
@@ -686,6 +686,15 @@ class TestLoadTxt(TestCase):
                      dtype=dt)
         assert_array_equal(x, a)
 
+    def test_str_dtype(self):
+        # see gh-8033
+        c = ["str1", "str2"]
+
+        for dt in (str, np.bytes_):
+            a = np.array(["str1", "str2"], dtype=dt)
+            x = np.loadtxt(c, dtype=dt)
+            assert_array_equal(x, a)
+
     def test_empty_file(self):
         with suppress_warnings() as sup:
             sup.filter(message="loadtxt: Empty input file:")