Added labels keyword when saving data to a txt file.

Author: Carlos Carreiras

biosppy/storage.py

@@ -278,45 +278,71 @@ def load_h5(path, label):
 
 
 def store_txt(path, data, sampling_rate=1000., resolution=None, date=None,
-              precision=6):
+              labels=None, precision=6):
     """Store data to a simple text file.
 
     Parameters
     ----------
     path : str
         Path to file.
     data : array
-        Data to store.
+        Data to store (up to 2 dimensions).
     sampling_rate : int, float, optional
         Sampling frequency (Hz).
     resolution : int, optional
         Sampling resolution.
     date : datetime, str, optional
         Datetime object, or an ISO 8601 formatted date-time string.
+    labels : list, optional
+        Labels for each column of `data`.
     precision : int, optional
         Precision for string conversion.
 
+    Raises
+    ------
+    ValueError
+        If the number of data dimensions is greater than 2.
+    ValueError
+        If the number of labels is inconsistent with the data.
+
     """
 
     # ensure numpy
     data = np.array(data)
 
+    # check dimension
+    if data.ndim > 2:
+        raise ValueError("Number of data dimensions cannot be greater than 2.")
+
     # build header
     header = "Simple Text Format\n"
-    header += "Sampling Rate (Hz): %0.2f\n" % sampling_rate
+    header += "Sampling Rate (Hz):= %0.2f\n" % sampling_rate
     if resolution is not None:
-        header += "Resolution: %d\n" % resolution
+        header += "Resolution:= %d\n" % resolution
     if date is not None:
         if isinstance(date, basestring):
-            header += "Date: %s\n" % date
+            header += "Date:= %s\n" % date
         elif isinstance(date, datetime.datetime):
-            header += "Date: %s\n" % date.isoformat()
+            header += "Date:= %s\n" % date.isoformat()
     else:
         ct = datetime.datetime.utcnow().isoformat()
-        header += "Date: %s\n" % ct
+        header += "Date:= %s\n" % ct
 
     # data type
-    header += "Data Type: %s" % data.dtype
+    header += "Data Type:= %s\n" % data.dtype
+
+    # labels
+    if data.ndim == 1:
+        ncols = 1
+    elif data.ndim == 2:
+        ncols = data.shape[1]
+
+    if labels is None:
+        labels = ['%d' % i for i in xrange(ncols)]
+    elif len(labels) != ncols:
+        raise ValueError("Inconsistent number of labels.")
+
+    header += "Labels:= %s" % '\t'.join(labels)
 
     # normalize path
     path = utils.normpath(path)
@@ -361,14 +387,14 @@ def load_txt(path):
 
     # extract header
     mdata_tmp = {}
-    fields = ['Sampling Rate', 'Resolution', 'Date', 'Data Type']
+    fields = ['Sampling Rate', 'Resolution', 'Date', 'Data Type', 'Labels']
     values = []
     for item in lines:
         if '#' in item:
             # parse comment
             for f in fields:
                 if f in item:
-                    mdata_tmp[f] = item.split(': ')[1].strip()
+                    mdata_tmp[f] = item.split(':= ')[1].strip()
                     fields.remove(f)
                     break
         else:
@@ -394,6 +420,11 @@ def load_txt(path):
         mdata['date'] = d
     except (KeyError, ValueError):
         pass
+    try:
+        labels = mdata_tmp['Labels'].split('\t')
+        mdata['labels'] = labels
+    except KeyError:
+        pass
 
     # load array
     data = np.genfromtxt(values, dtype=dtype, delimiter='\t')