Made logging to file optional.

pysegcnn/core/logging.py

@@ -18,8 +18,38 @@ License
 import pathlib
 
 
+# logging configuration dictionary
+LOGGING_CONFIG = {
+    'version': 1,
+    'disable_existing_loggers': False,
+    'formatters': {
+        'brief': {
+            'format': '%(name)s: %(message)s'
+            },
+        'standard': {
+            'format': '%(asctime)s [%(levelname)s] %(name)s: %(message)s',
+            'datefmt': '%Y-%m-%dT%H:%M:%S'
+            },
+    },
+    'handlers': {
+        'console': {
+            'class': 'logging.StreamHandler',
+            'formatter': 'brief',
+            'level': 'INFO',
+            'stream': 'ext://sys.stderr',
+        },
+    },
+    'loggers': {
+        '': {
+            'handlers': ['console'],
+            'level': 'INFO',
+        },
+    }
+}
+
+
 # the logging configuration dictionary
-def log_conf(logfile):
+def log_conf(logfile=None):
     """Set basic logging configuration.
 
     See the logging `docs`_ for a detailed description of the configuration
@@ -31,7 +61,8 @@ def log_conf(logfile):
     Parameters
     ----------
     logfile : `str` or :py:class:`pathlib.Path`
-        The file to save the logs to.
+        The file to save the logs to. The default is `None`, which means only
+        log to stdout and not to file.
 
     Returns
     -------
@@ -40,44 +71,19 @@ def log_conf(logfile):
 
     """
     # check if the parent directory of the log file exists
-    logfile = pathlib.Path(logfile)
-    if not logfile.parent.is_dir():
-        logfile.parent.mkdir(parents=True, exist_ok=True)
-
-    LOGGING_CONFIG = {
-        'version': 1,
-        'disable_existing_loggers': False,
-        'formatters': {
-            'brief': {
-                'format': '%(name)s: %(message)s'
-                },
-            'standard': {
-                'format': '%(asctime)s [%(levelname)s] %(name)s: %(message)s',
-                'datefmt': '%Y-%m-%dT%H:%M:%S'
-                },
-        },
-        'handlers': {
-            'console': {
-                'class': 'logging.StreamHandler',
-                'formatter': 'brief',
-                'level': 'INFO',
-                'stream': 'ext://sys.stderr',
-            },
+    if logfile is not None:
+        logfile = pathlib.Path(logfile)
+        if not logfile.parent.is_dir():
+            logfile.parent.mkdir(parents=True, exist_ok=True)
 
-            'file': {
+        # add log file to logging configuration
+        LOGGING_CONFIG['handlers']['file'] = {
                 'class': 'logging.FileHandler',
                 'formatter': 'standard',
                 'level': 'INFO',
                 'filename': logfile,
                 'mode': 'a'
             }
-        },
-        'loggers': {
-            '': {
-                'handlers': ['console', 'file'],
-                'level': 'INFO',
-            },
-        }
-    }
+        LOGGING_CONFIG['loggers']['']['handlers'].append('file')
 
     return LOGGING_CONFIG