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How to round the number in Python?

weboom — Tue, 29 Dec 2009 00:52:12 +0000

I want to make
x=32.34565
to
32.35

How ?
round(x,2)

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()

High-level copy in Python: shutil

weboom — Mon, 30 Nov 2009 03:10:40 +0000

You can use shutil for high-level file operation (copy, move, delete etc.) in Python.

e.g.,

>>>import shutil

>>>shutil.copy(src,dest)

src is a source file.

dest is a target directory.

How to tell if it is directory or file in Python

weboom — Mon, 30 Nov 2009 03:08:23 +0000

>>>import os

>>>os.path.isdir(fileordirectoryname)

If directory, its output will be True.

If not, it will be False.

How to list files and subdirectories within a directory (Python)

weboom — Mon, 30 Nov 2009 03:05:38 +0000

>>>import os

>>>os.listdir(‘.’)

This will make a list containing the names of files and subdirectories.

How to change directory in python

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

>>>import os

>>>os.chdir(‘..’)

>>>os.chdir(‘/home/weboom/’)

How to pass command line argument in Python

weboom — Sat, 28 Nov 2009 08:21:35 +0000

>python program.py arg1 arg2

To get arg1 and arg2

——-

import sys

arg1 = sys.argv[1]

arg2 = sys.argv[2]

List Index out of Range

weboom — Wed, 18 Nov 2009 22:25:28 +0000

You will get this error when there is no list element to access.

For example,

L=[1, 2, 3]

L[4] doesn’t exist.

If you try to call L[4], you will get the above error.