fix #15 implement dynamic capacity to text

This commit implements a new capasity to human readable string function
that supports all kinds of speeds ranging from 1k to 1000Exabit++

utils.py

@@ -58,22 +58,28 @@ def edge_labels(edges, edgegroups=[], suppress_default=True):
 
 
 def cap2str(capacity):
-
-    mapping = {  1984     : '2Mbit/s',
-                34000     : '34Mbit/s',
-                34010     : '34Mbit/s',
-                100000    : '100Mbit/s',
-                155000    : '155Mbit/s',
-                1000000   : '1Gbit/s',
-                2488000   : '2.5Gbit/s',
-                10000000  : '10Gbit/s',
-                100000000 : '100Gbit/s'
-              }
-
-    if type(capacity) != type(int):
-        capacity = int(capacity)
-    if not capacity in mapping: return "Unkown"
-    return mapping[capacity]
+    """Capacity to Human Readable string convertion
+
+    Converts the given Capacity in Kbit to human readable representation,
+    It will return a one digit decimal precition and omitts the decimal 
+    if its zero
+    """
+    if capacity < 1000: 
+        s, i = "K", float(capacity) 
+    elif capacity < 1000000: 
+        s, i = "M", round(float(capacity)/1000.0, 1) 
+    elif capacity < 1000000000: 
+        s, i = "G", round(float(capacity)/1000000.0, 1) 
+    elif capacity < 1000000000000: 
+        s, i = "T", round(float(capacity)/1000000000.0,1) 
+    else: 
+        s, i = "E", round(float(capacity)/1000000000000.0,1)
+         
+
+    if i % 1 == 0: 
+        return "{:0.0f}{}bit/s".format(i, s) 
+    else: 
+        return "{:0.1f}{}bit/s".format(i, s) 
 
 def read_linkloads(G, host, url):