MAINT: Fix alerts from http://lgtm.com (#9292)

* make exception raising 2/3 compatible
* remove unnecesary else statement after while loop without break clause
* ensure file is always enclosed even in the event of an exception
* ensure list comprehension variable does not override enclosing loop variable

4 files changed, 41 insertions, 50 deletions

diff --git a/numpy/_import_tools.py b/numpy/_import_tools.py
index 18ac78d29..cb8bc477c 100644
--- a/numpy/_import_tools.py
+++ b/numpy/_import_tools.py
@@ -303,8 +303,7 @@ class PackageLoader(object):
                     lines.append(line)
                     line = tab
                 line += ' ' + word
-            else:
-                lines.append(line)
+            lines.append(line)
         return '\n'.join(lines)
 
     def get_pkgdocs(self):
diff --git a/numpy/f2py/crackfortran.py b/numpy/f2py/crackfortran.py
index 0f5e6e023..677f4bae3 100755
--- a/numpy/f2py/crackfortran.py
+++ b/numpy/f2py/crackfortran.py
@@ -308,22 +308,21 @@ def is_free_format(file):
     # f90 allows both fixed and free format, assuming fixed unless
     # signs of free format are detected.
     result = 0
-    f = open(file, 'r')
-    line = f.readline()
-    n = 15  # the number of non-comment lines to scan for hints
-    if _has_f_header(line):
-        n = 0
-    elif _has_f90_header(line):
-        n = 0
-        result = 1
-    while n > 0 and line:
-        if line[0] != '!' and line.strip():
-            n -= 1
-            if (line[0] != '\t' and _free_f90_start(line[:5])) or line[-2:-1] == '&':
-                result = 1
-                break
+    with open(file, 'r') as f:
         line = f.readline()
-    f.close()
+        n = 15  # the number of non-comment lines to scan for hints
+        if _has_f_header(line):
+            n = 0
+        elif _has_f90_header(line):
+            n = 0
+            result = 1
+        while n > 0 and line:
+            if line[0] != '!' and line.strip():
+                n -= 1
+                if (line[0] != '\t' and _free_f90_start(line[:5])) or line[-2:-1] == '&':
+                    result = 1
+                    break
+            line = f.readline()
     return result
 
 
@@ -3335,8 +3334,7 @@ if __name__ == "__main__":
     if pyffilename:
         outmess('Writing fortran code to file %s\n' % repr(pyffilename), 0)
         pyf = crack2fortran(postlist)
-        f = open(pyffilename, 'w')
-        f.write(pyf)
-        f.close()
+        with open(pyffilename, 'w') as f: 
+            f.write(pyf)
     if showblocklist:
         show(postlist)
diff --git a/numpy/lib/npyio.py b/numpy/lib/npyio.py
index cb3b7534d..187a6722a 100644
--- a/numpy/lib/npyio.py
+++ b/numpy/lib/npyio.py
@@ -1014,7 +1014,7 @@ def loadtxt(fname, dtype=float, comments='#', delimiter=None,
             if len(vals) == 0:
                 continue
             if usecols:
-                vals = [vals[i] for i in usecols]
+                vals = [vals[j] for j in usecols]
             if len(vals) != N:
                 line_num = i + skiprows + 1
                 raise ValueError("Wrong number of columns at line %d"
diff --git a/tools/npy_tempita/__init__.py b/tools/npy_tempita/__init__.py
index daf2606c8..dfb40e965 100644
--- a/tools/npy_tempita/__init__.py
+++ b/tools/npy_tempita/__init__.py
@@ -153,9 +153,8 @@ class Template(object):
 
     def from_filename(cls, filename, namespace=None, encoding=None,
                       default_inherit=None, get_template=get_file_template):
-        f = open(filename, 'rb')
-        c = f.read()
-        f.close()
+        with open(filename, 'rb') as f:
+            c = f.read()
         if encoding:
             c = c.decode(encoding)
         elif PY3:
@@ -315,33 +314,31 @@ class Template(object):
                     'invalid syntax in expression: %s' % code)
             return value
         except:
-            exc_info = sys.exc_info()
-            e = exc_info[1]
-            if getattr(e, 'args', None):
-                arg0 = e.args[0]
+            e_type, e_value, e_traceback = sys.exc_info()
+            if getattr(e_value, 'args', None):
+                arg0 = e_value.args[0]
             else:
-                arg0 = coerce_text(e)
-            e.args = (self._add_line_info(arg0, pos),)
+                arg0 = coerce_text(e_value)
+            e_value.args = (self._add_line_info(arg0, pos),)            
             if PY3:
-                raise(e)
+                raise e_value
             else:
-                raise (exc_info[1], e, exc_info[2])
+                exec('raise e_type, e_value, e_traceback')
 
     def _exec(self, code, ns, pos):
         # __traceback_hide__ = True
         try:
             exec(code, self.default_namespace, ns)
         except:
-            exc_info = sys.exc_info()
-            e = exc_info[1]
-            if e.args:
-                e.args = (self._add_line_info(e.args[0], pos),)
+            e_type, e_value, e_traceback = sys.exc_info()
+            if e_value.args:
+                e_value.args = (self._add_line_info(e_value.args[0], pos),)
             else:
-                e.args = (self._add_line_info(None, pos),)
+                e_value.args = (self._add_line_info(None, pos),)
             if PY3:
-                raise(e)
+                raise e_value
             else:
-                raise (exc_info[1], e, exc_info[2])
+                exec('raise e_type, e_value, e_traceback')
 
     def _repr(self, value, pos):
         # __traceback_hide__ = True
@@ -358,13 +355,12 @@ class Template(object):
                 if (is_unicode(value) and self.default_encoding):
                     value = value.encode(self.default_encoding)
         except:
-            exc_info = sys.exc_info()
-            e = exc_info[1]
-            e.args = (self._add_line_info(e.args[0], pos),)
+            e_type, e_value, e_traceback = sys.exc_info()
+            e_value.args = (self._add_line_info(e_value.args[0], pos),)
             if PY3:
-                raise(e)
+                raise e_value
             else:
-                raise (exc_info[1], e, exc_info[2])
+                exec('raise e_type, e_value, e_traceback')
         else:
             if self._unicode and isinstance(value, bytes):
                 if not self.default_encoding:
@@ -1295,9 +1291,8 @@ def fill_command(args=None):
         template_content = sys.stdin.read()
         template_name = '<stdin>'
     else:
-        f = open(template_name, 'rb', encoding="latin-1")
-        template_content = f.read()
-        f.close()
+        with open(template_name, 'rb', encoding="latin-1") as f: 
+            template_content = f.read()
     if options.use_html:
         TemplateClass = HTMLTemplate
     else:
@@ -1305,9 +1300,8 @@ def fill_command(args=None):
     template = TemplateClass(template_content, name=template_name)
     result = template.substitute(vars)
     if options.output:
-        f = open(options.output, 'wb')
-        f.write(result)
-        f.close()
+        with open(options.output, 'wb') as f: 
+            f.write(result)
     else:
         sys.stdout.write(result)