根據密碼學的明文推斷中的統計學規律，一個英語文段中字母字頻有一定的規律。因而對莎士比亞的多份作品做了基本的字頻分析。

1. 指令碼

   import sys
   import csv
   
   if(len(sys.argv) != 2):
       exit(-2)
   
   filename = sys.argv[1]
   alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"#所有正常列印字元
   strings = open(filename).read()#讀取需要統計頻數的文字
   
   len = len(strings)
   
   result = {}
   for i in alphabet:
       counts = strings.count(i)
       i = '{0}'.format(i)
       result[i] = counts
   
   res = sorted(result.items(), key=lambda item: item[1], reverse=True)
   num = 0
   print("Statistic file "+ filename+" ...")
   print("Result sheet will be saved to "+filename+".analysis.csv\n")
   
   for data in res:
       num += 1
       print("Char '" + data[0] + "' appeared "+ str(data[1]) + "times with percentage "+ str( 100 * data[1]/len) + "%")
   
   print('\nRESULT')
   
   for i in res:
       flag = str(i[0])
       print(flag[0], end="")
   
   with open(filename+".analysis.csv", "w",encoding='utf-8',newline='') as csvfile:  # 開啟檔案
   
       writer = csv.writer(csvfile)
   
       #先寫入columns_name
       writer.writerow(["char","count"])
       #寫入多行用writerows
       writer.writerows(res)
    
   

2. 示例資料（以hamlet_TXT_FolgerShakespeare.txt.analysis.csv為例）

   1. csv檔案
      此分析檔案包含了對整個個文段，即資料夾/text下的對應文章的字元個數分析結果。

   2. .txt.output.txt檔案
      此檔案格式如下

      Statistic file hamlet_TXT_FolgerShakespeare.txt ... 
      #從hamlet_TXT_FolgerShakespeare.txt統計字頻
      Result sheet will be saved to hamlet_TXT_FolgerShakespeare.txt.analysis.csv
      #將此字頻表儲存到hamlet_TXT_FolgerShakespeare.txt.analysis.csv
      
      Char 	'e' appeared 	14843 times	(8.396026834704106%)
      #字元	   'e'出現了		14843次，頻率為8.396026834704106%
      Char 	't' appeared 	10981 times	(6.211464708743905%)
      #...
      Char 	'8' appeared 	0 times	(0.0%)
      
      Sorting result:
      #按照出現先後排序
      etoasnhirldumywfcgpbTAIvEkHLONRMSWGPUBCDFKxYQqjzVZJ123450679X8
       
      

下載附件