代码如下

# __author__ == 'xjiao'
# -*- coding:utf-8 -*-

import csv

def readTable(fileobj):
    """Read Periodic Table file into a dict.with element symbol as key."""
    dataFile = csv.reader(fileobj)
    periodicTable = {}

    for row in dataFile:
        #ignore header rows:elements begin with a number
        if row[0].isdigit():
            symbol = row[1]
            periodicTable[symbol] = row[:8]   #ignore end of row

    return periodicTable

def parseElement(elementStr):
    """Parse element string into symbol and quantity.
    e.e. Si2 return （'Si',s）"""

    symbol = ""
    quantity = ""
    for ch in elementStr:
        if ch.isalpha():
            symbol = symbol + ch
        else:
            quantity = quantity + ch
    if quantity == "":#if no number,default is 1
        quantity = 1

    return symbol,int(quantity)

#Read file
fileHandle = open('Periodic-Table.csv','rU')

#Create Dictionary of Periodic Table using element symbols as keys
periodicTable = readTable(fileHandle)

#Promot for input and convert compound into a list of element
compoundString = \
    raw_input("Input a chemical compound,hyphenated,e.g. C-O2:")
compoundList = compoundString.split('-')

#Initialize atomic mass
mass = 0
print "The compound is composed of:",

#Parse comound list into symbol-quantity pairs,print name,and add mass
for c in compoundList:
    symbol,quantity = parseElement(c)
    print periodicTable[symbol][5], #print element name
    mass = mass +quantity*float(periodicTable[symbol][6])

print "\n\nThe atomic mass of the compound is",mass

fileHandle.close()

输出结果如下：

D:\python\python.exe E:/python_project/Chapter8-3.py
Input a chemical compound,hyphenated,e.g. C-O2:H2-S-O4
The compound is composed of: hydrogen sulfur oxygen 

The atomic mass of the compound is 98.086

Process finished with exit code 0