add default objects if loading fails

src/data.py

@@ -2,6 +2,8 @@
 # -*- coding: utf-8 -*-
 """Read and write data to or from file.
 
+:Date: 2019-06-12
+
 .. module:: data
   :platform: *nix, Windows
   :synopsis: Handle data files.
@@ -11,7 +13,7 @@
 from __future__ import print_function
 import pickle
 
-def data_read(file_name, x_column, y_column):
+def data_read(file_name, x_column, y_column, default=None, verbose=False):
   """Read ascii data file.
 
   :param filename: file to read
@@ -20,27 +22,43 @@ def data_read(file_name, x_column, y_column):
   :type x_column: int
   :param y_column: column index for the y data (first column is 0)
   :type y_column: int
+  :param default: return object if data loading fails
+  :type default: object
+  :param verbose: verbose information (default = False)
+  :type verbose: bool
 
   :returns: x and y
   :rtype: tuple(list, list)
   """
   import re
-  file = open(file_name)
-  x = []
-  y = []
-  for row in file:
-    fields = re.split(r'\s+', row.strip())
-    #print(filds)
-    x.append(float(fields[x_column]))
-    y.append(float(fields[y_column]))
-  file.close()
+
+  x = default
+  y = default
+
+  if verbose:
+    print('check if data is available')
+  try:
+    file = open(file_name)
+    x = []
+    y = []
+    for row in file:
+      fields = re.split(r'\s+', row.strip())
+      #print(filds)
+      x.append(float(fields[x_column]))
+      y.append(float(fields[y_column]))
+    file.close()
+  except IOError:
+    if verbose:
+      print('data file not found')
   return x, y
 
-def data_load(file_name, verbose=False):
+def data_load(file_name, default=None, verbose=False):
   """Load stored program objects from binary file.
 
   :param file_name: file to load
   :type file_name: str
+  :param default: return object if data loading fails
+  :type default: object
   :param verbose: verbose information (default = False)
   :type verbose: bool
 
@@ -56,7 +74,7 @@ def data_load(file_name, verbose=False):
       print('found:')
       print(object_data)
   except IOError:
-    object_data = None
+    object_data = default
     if verbose:
       print('no saved datas found')
   return object_data