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How to write lines (Python)

weboom — Tue, 22 Dec 2009 19:53:16 +0000

Use writelines()

e.g.

# read lines in a file

import sys

arg1 = sys.argv[1]
f = open(arg1, 'r')
lines = f.readlines()

f.close()
arg='out_'+arg1

FILE=open(arg,'w')
for line in lines:

     words = line.split(' ')

     if words[1] == 'hypnos':

          FILE.writelines(line)

FILE.close()

Find word in a string (Python)

weboom — Tue, 22 Dec 2009 19:36:21 +0000

When you want to find a word in a string, use find()

e.g.

import sys

arg1 = sys.argv[1] # passing the first argument
if arg1.find("off") == -1: # if arg1 does not contain "off"

  # do something

else:

  # do something

Python: How to read lines

weboom — Tue, 22 Dec 2009 19:32:44 +0000

Use readlines()

For example,

arg = "filename"

f = open(arg, 'r')

lines = f.readlines()
f.close()

How to change directory in python

weboom — Mon, 30 Nov 2009 02:59:50 +0000

>>>import os

>>>os.chdir(‘..’)

>>>os.chdir(‘/home/weboom/’)

Do you want to use datetime.datetime.now ?

weboom — Tue, 04 Aug 2009 07:49:13 +0000

Then,

import datetime

What is Python dictionary?

weboom — Sun, 02 Aug 2009 19:18:28 +0000

If you don’t want to refer to the elements of a collection by their position number but prefer some other type of object as a key,

use a python dictionary

———–

e.g.,

>>> tel = {'jack': 4098, 'sape': 4139}
>>> tel['guido'] = 4127
>>> tel
{'sape': 4139, 'guido': 4127, 'jack': 4098}
>>> tel['jack']
4098
>>> del tel['sape']
>>> tel['irv'] = 4127
>>> tel
{'guido': 4127, 'irv': 4127, 'jack': 4098}
>>> tel.keys()
['guido', 'irv', 'jack']
>>> 'guido' in tel
True

list vs. tuple

weboom — Sun, 02 Aug 2009 19:12:40 +0000

Python list and tuple, both of them consists of multiple objects identified its position.

list

L=[1, 2, 3]

tuple

T=(1,2,3)

Difference between them is that tuple is immutable.

That is,

L[0]=100

is OK, but

T[0]=100

is not allowed.

What is Python tuple?

weboom — Sun, 02 Aug 2009 19:09:51 +0000

Python tuple

consist of a number of objects which can be referenced by their position number within the object.

———

e.g.,

fruit = (“Apple”,”Banana”,”Cherry”,”Fig”,”Grapefruit”)

What for "unicode"?

weboom — Sun, 02 Aug 2009 05:22:02 +0000

__unicode__

is for displaying objects.

———–

For example,

>>>p = Card.objects.create(name=’Hot Pot’, city=’San Diego’)

>>>card_list = Card.objects.all()

>>>card_list

[]

without __unicode__, you will see just “Card object”

if you define __unicode__

def __unicode__(self):

return self.name

then, you will see

[]

What is Python list?

weboom — Sun, 02 Aug 2009 05:02:49 +0000

Python list

is a container that holds a number of other objects, in a given order.

L=[1, 2, 3, 4]