also deal with differences in size_str

diff --git a/src/file_helpers.py b/src/file_helpers.py
index b9e932b..e98937c 100644 (file)
--- a/src/file_helpers.py
+++ b/src/file_helpers.py
@@ -404,24 +404,39 @@ def find_mount_point(path):
     return path
 
 
-def size_str(byte_number):
-    """ round byte_number to something easily human-readable like '1.5G' """
+def size_str(byte_number, is_diff=False):
+    """ round byte_number to something easily human-readable like '1.5G'
 
+    :param bool is_diff: set to True to include a '+' or '-' in output;
+                         default: False
+    """
+
+    # constants
     units = 'B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'
     factor = 1024
     thresh_add_comma = 10.   # below this, return 1.2G, above this return 12G
 
+    # prepare
+    if byte_number < 0:
+        sign_str = '-'
+    elif is_diff:
+        sign_str = '+'
+    else:
+        sign_str = ''
     curr_fac = 1
-    curr_num = float(byte_number)
+    curr_num = abs(float(byte_number))
+
+    # loop
     for unit in units:
         if curr_num > factor:
             curr_num /= factor
             continue
         elif curr_num < thresh_add_comma and unit != 'B':   # e.g. 1.2G
-            return '{0:.1f}{1}'.format(curr_num, unit)
+            return '{2}{0:.1f}{1}'.format(curr_num, unit, sign_str)
         else:   # e.g. 12G or 1B
-            return '{0:d}{1}'.format(int(round(curr_num)), unit)
+            return '{2}{0:d}{1}'.format(int(round(curr_num)), unit, sign_str)
 
     # have an impossible amount of data.  (>1024**4 GB)
     # undo last "/factor" and show thousand-separator
-    return '{0:,d}{1}'.format(int(round(curr_num*factor)), units[-1])
+    return '{2}{0:,d}{1}'.format(int(round(curr_num*factor)), units[-1],
+                                 sign_str)