''' # Python 2.3
fn = r'H:\TEMP\temsys\elements.txt'
data = [item.split()
for item in open(fn).readlines()]
dataDict
= dict(zip([float(i[1]) for
i in data], [j[0] for j in data]))
print dataDict
keys = dataDict.keys()
keys.sort()
outList
= [[dataDict[key], '%0.5f' % key] for key in keys]
print outList
'''
# Python 2.4
fn = r'H:\TEMP\temsys\elements.txt'
data = [item.split()
for item in open(fn).readlines()]
dataDict
= dict(zip([float(i[1]) for
i in data], [j[0] for j in data]))
print dataDict
outList
= [[dataDict[key], '%01.5f' % key] for key in sorted(dataDict.keys())]
print outList
''' Data
Ac 227.0
Ag 107.868
Al 26.98154
Am 241.1
Ar 39.948
As 74.9216
'''
'''
>>>
{39.948: 'Ar', 227.0: 'Ac',
[['Al', '26.98154'],
['Ar', '39.94800'], ['As', '74.92160'], ['Ag',
'107.86800'], ['Ac', '227.00000'], ['Am', '241.10000']]
>>>
'''
'''
dataList
= [[float(weight), elem] for elem,
weight in [item.split() for item in data]]
dataList.sort()
print dataList
'''