2013年8月12日Python的5個最有價值問題

問:Python怎麼在字典裏刪除值但保留相應的鍵

答:

假設3都在值裏,而非鍵
>>> for v in D1.values():
...     if 3 in v:
...         v.remove(3)
...
>>> D1
{'A1': [2], 'C1': [4, 5], 'B1': [3]}

這個代碼還能適用於更多狀況,好比:
>>> D1 = {'A1' : [2, 3], 'B1': [3, 3], 'C1' : [4, 5]}
>>> for k, v in D1.items():
...     D1[k] = filter(lambda x: x!=3, v)
...
>>> D1
{'A1': [2], 'C1': [4, 5], 'B1': []}

問:Python的TKinter框架怎麼建立實體表

答:

from Tkinter import *

from string import ascii_lowercase

  

class app(Frame):

     def __init__( self , master = None ):

         Frame.__init__( self , master)

         self .grid()

         self .create_widgets()

  

     def create_widgets( self ):

         self .entries = {}

         self .tableheight = 9

         self .tablewidth = 9

         counter = 0

         for row in xrange ( self .tableheight):

             for column in xrange ( self .tablewidth):

                 self .entries[counter] = Entry( self , width = 5 )

                 self .entries[counter].grid(row = row, column = column)

                 counter + = 1

  

prog = app()

prog.master.title( 'Sudoku' )

prog.mainloop()

 

問:Python怎麼轉換Dictionary爲DataFrame?

答:

import json

import pandas as pd

  

db = json.loads( open ( 'pruItems.json' , 'r' ).read())

pieces = []

for d in db:

     if d[ 'data' ]:

         df = pd.DataFrame(d[ 'data' ])

         df.columns = [ 'date' , 'bid' , 'ask' ]

         df = df.set_index( 'date' )

         pieces.append(df)

  

df = pd.concat(pieces, axis = 1 , keys = [d[ 'fund' ] for d in db])

  

print df

輸出:

                 TGC               FEF              FAF       

                 bid      ask      bid      ask     bid     ask

date                                                         

18/06/2013  34.8400  34.8400  14.9179  14.9179  6.6780  6.6780

17/06/2013  34.4900  34.4900  14.8712  14.8712  6.6510  6.6570

 

問:Python怎麼使用BeautifulSoup來提取兩個Html標籤之間的內容

答:

使用.content

>>> from bs4 import BeautifulSoup as BS

>>> html = """<li class="li_dataline2">

...

...

... <b> Expiry date: </b>14/09/2013

...

...

... </li>"""

>>> soup = BS(html)

>>> print soup.find( 'li' , { 'class' : 'li_dataline2' }).contents[ - 1 ].strip()

14 / 09 / 2013