= Python =
Python is a programming language that lets you work more quickly and integrate your systems more effectively.
Links:
* [[http://docs.python.org/2/library/]]
* [[http://www.tutorialspoint.com/python/]]
== Python3 ==
=== Install from SlackBuild ===
* cd /tmp
* wget http://slackbuilds.org/slackbuilds/13.1/development/python3.tar.gz
* tar xvzf python3.tar.gz
* cd python3
* wget http://python.org/ftp/python/3.1.3/Python-3.1.3.tar.bz2
* ./python3.SlackBuild
* installpkg /tmp/python3-3.1.1-i486-1_SBo.tgz
== UTF-8 ==
At the start of source code files:
{{{#!highlight python
# -*- coding: utf-8 -*-
print u"Olá mundo" # hello world in portuguese
}}}
Letter '''á''' is encoded as hexadecimal '''0xC3A1''' in UTF-8 and as '''0x00E1''' in UTF-16.
[[http://www.fileformat.info/info/unicode/char/e1/index.htm]]
Letter '''ú''' is encoded as hexadecimal '''0xC3BA''' in UTF-8, as '''0x00FA''' in UTF-16 and as '''0xFA''' in latin-1/ISO8859-1/CP-1252.
{{{#!highlight python
#utf-8 data
utf81 ='\xc3\xba'
# convert from utf-8 to unicode
unic = utf81.decode('utf-8')
for c in unic:
print '%04X'%(ord(c))
# convert from unicode to latin1/ISO8859-1 CP-1252
lat1=unic.encode('latin1')
for c in lat1:
print '%02X'%(ord(c))
}}}
== Utf-8 and Unicode ==
{{{#!highlight python
utf81='\xe1\xb7\x97' #utf-8 data
unic = utf81.decode('utf-8') #converts from utf-8 to unicode (utf-16)
for c in unic:
print '%04X'%(ord(c))
type(unic) # unicode, 2 bytes per char
type(utf81) # str, 1 bytes per char
}}}
== Time and date ==
{{{#!highlight python
import time
# get seconds since epoch until now in UTC to a string year-month-dayThour:minute:second
strutc = time.strftime('%Y-%m-%dT%H:%M:%S', time.gmtime() )
# get seconds since epoch until now in localtime to a string year-month-dayThour:minute:second
strlocal = time.strftime('%Y-%m-%dT%H:%M:%S', time.localtime() )
# number seconds since epoch
nrSeconds = time.mktime(time.gmtime())
nrSeconds = time.time() #usually is UTC on all OS
# from timestamp to string date
import datetime
print(datetime.datetime.fromtimestamp(1284101485).strftime('%Y-%m-%d %H:%M:%S'))
#
def toUTCDateStr(timestamp):
return datetime.datetime.utcfromtimestamp( timestamp ).strftime('%Y-%m-%d %H:%M:%S ')
# timedelta
import datetime
x=datetime.datetime.fromtimestamp(1284101485)
nowx=datetime.datetime.now()
ts=(nowx-x).total_seconds()
print int(ts)
### add , subtract days
import datetime
x = datetime.datetime(2014,1,2)
print x
y = x - datetime.timedelta(days=1)
print y
z = y - datetime.timedelta(days=1)
print z
### convert string with date to time tuple
import time
timeTuple = time.strptime('2014-01-01 10:11:12','%Y-%m-%d %H:%M:%S')
nrSecondsSince1970=time.mktime(timeTuple)
### get seconds since epoch
start = int(datetime.datetime(2014,3,9,0,0,0,0).strftime("%s"))*1000
end = int(datetime.datetime(2014,3,14,23,59,59,999).strftime("%s"))*1000
### string from utc current date
currutc=datetime.datetime.utcnow().strftime("%Y-%m-%d %H:%M:%S")
}}}
== Write and reading data for a plist file ==
A plist file stores data in XML format.
{{{#!highlight python
import plistlib
value = [{'key1':123,'key2':'asdf'},{'keyx1':'testing','keyz1':'yup'}]
# save value in plist file
plistlib.writePlist(value,'/tmp/plist1.plist')
o=plistlib.readPlist('/tmp/plist1.plist')
print o
}}}
Content of the file '''/tmp/plist1.plist'''
{{{#!highlight xml
key1
123
key2
asdf
keyx1
testing
keyz1
yup
}}}
== Threading ==
{{{#!highlight python
#!/usr/bin/python
# timestable.py
# calculates the times table in concurrency
import threading
import time
class TimesTable (threading.Thread):
def __init__(self, timesTable):
threading.Thread.__init__(self) #required
self.timeTable = timesTable
self.count = 1
def run(self):
loop=True
while loop:
time.sleep(1) #sleep for 1 second
result=self.timeTable * self.count
print "%d*%d=%d"%(self.timeTable,self.count,result)
if self.count<10:
self.count = self.count+1
else:
self.count=1
# create threads
timesTable2 = TimesTable(2)
timesTable5 = TimesTable(7)
# start the threads
timesTable2.start()
timesTable5.start()
}}}
== unit tests (pyunit) ==
{{{#!highlight python
#filename: unitTest.py
#Run tests: python unitTest.py
#Should fail on testAdd2
import unittest
class SimpleTestCase(unittest.TestCase):
def setUp(self):
self.res=4
def tearDown(self):
self.res=0
def testAdd1(self):
res=2+2
self.assertEqual(self.res,res,'')
def testAdd2(self):
res=2+3
self.assertEqual(self.res,res,'')
def testAdd3(self):
res=2+3
self.assertNotEqual(self.res,res,'')
if __name__ == '__main__':
unittest.main()
}}}
== unit tests coverage (pyunit) ==
* http://coverage.readthedocs.io/en/latest/cmd.html
* pip install coverage
'''tests.py'''
{{{#!highlight python
import unittest
from impl import add
from impl import sub
class TestCase(unittest.TestCase):
def test_add(self):
self.assertEqual(5,add(2,3))
# def test_sub(self):
# self.assertEqual(1,add(3,2))
if __name__ == '__main__':
unittest.main()
}}}
'''impl.py'''
{{{#!highlight python
def add(arg1,arg2):
return arg1+arg2
def sub(arg1,arg2):
return arg-+arg2
}}}
Steps:
* coverage erase
* coverage run tests.py
* coverage report -m impl.py
* coverage html impl.py #in htmlcov folder
== cython ==
Installation:
* su
* cd /tmp
* wget http://cython.org/release/Cython-0.19.1.tar.gz
* tar xvzf Cython-0.19.1.tar.gz
* cd Cython-0.19.1
* python setup.py build
* python setup.py install
== pymssql ==
Requires cython.
Installation:
* su
* cd /tmp
* wget [[http://pymssql.googlecode.com/files/pymssql-2.0.0b1-dev-20111019.tar.gz]]
* tar xvvzf pymssql-2.0.0b1-dev-20111019.tar.gz
* cd pymssql-2.0.0b1-dev-20111019
* python setup.py build
* python setup.py install
* python
* import pymssql
== pywhois ==
Python module for retrieving WHOIS information of domains [[http://code.google.com/p/pywhois/]].
Fetch code with mercurial:
* cd /tmp
* hg clone https://code.google.com/p/pywhois/
* cd pywhois
* python setup.py build
* python setup.py install
== Syntax highlighting on Vim for wsgi ==
Edit ~./.vimrc:
{{{#!highlight bash
syntax on
filetype on
au BufNewFile,BufRead *.wsgi set filetype=python
}}}
== Get file modification time ==
{{{#!highlight python
import os
nrSeconds=os.path.getmtime('/folder/file') # unix epoch, nr secs since 1970-01-01 00:00:00
}}}
== Kill process with PID ==
{{{#!highlight python
import os
import signal
os.kill(pid,signal.SIGTERM)
}}}
== Log message to /var/log/messages or /var/log/syslog ==
{{{#!highlight python
import syslog
syslog.syslog(syslog.LOG_INFO,'message to syslog')
}}}
{{{#!highlight python
import syslog
syslog.syslog(syslog.LOG_DEBUG,'DEBUG')
syslog.syslog(syslog.LOG_INFO,'INFO')
syslog.syslog(syslog.LOG_WARNING,'WARNING')
syslog.syslog(syslog.LOG_ERR,'ERR')
syslog.syslog(syslog.LOG_CRIT,'CRIT')
}}}
||OS||File||Logged levels||
||Slack64 14||/var/log/messages|| INFO ||
||Slack64 14||/var/log/syslog|| WARNING ERR CRIT ||
||CentOS 6.4||/var/log/messages|| INFO WARNING ERR CRIT ||
||Ubuntu 12.04 Precise||/var/log/syslog||DEBUG INFO WARNING ERR CRIT ||
||Debian 7.0 Wheezy||/var/log/syslog||DEBUG INFO WARNING ERR CRIT ||
== Simple process monitor ==
{{{#!highlight python
# example service, dummyService.py
import time
while True:
try:
f=open('filex.log','wb')
f.write('%f'%(time.time()))
f.close()
time.sleep(5)
except KeyboardInterrupt:
quit()
}}}
{{{#!highlight python
#service monitor.py
# * * * * * /usr/bin/python /home/vitor/svc/monitor.py
import os
import syslog
import subprocess
if __name__=="__main__":
files = os.listdir('/proc')
script="dummyService.py"
prefix="dummyService:"
svcRunning=False
for file in files:
if file.isdigit():
cmdline = open('/proc/%s/cmdline'%(file),'r').read()
proc = "%s %s "%(file,cmdline)
if script in proc :
svcRunning=True
if svcRunning==False:
syslog.syslog(syslog.LOG_INFO,'%s process created '%(prefix) )
# run exec process on python Popen
subprocess.Popen(['/usr/bin/python','dummyService.py'],cwd='/home/userx/svc')
}}}
== Read URL content ==
{{{#!highlight python
import urllib2
r=urllib2.urlopen('http://www.sapo.pt')
resp=r.read()
print resp
}}}
== Windows service ==
Install http://sourceforge.net/projects/pywin32/files/pywin32/Build%20218/pywin32-218.win32-py2.5.exe/download for Python 2.5 for Windows.
Adapted from http://ryrobes.com/python/running-python-scripts-as-a-windows-service/
{{{#!highlight python
# C:\cmt\test>python testWinSvc.py install
# C:\cmt\test>python testWinSvc.py start
# C:\cmt\test>python testWinSvc.py stop
# C:\cmt\test>python testWinSvc.py remove
# C:\cmt\test>service.msc
import win32service
import win32serviceutil
import win32api
import win32con
import win32event
import win32evtlogutil
import os, sys, string, time
class aservice(win32serviceutil.ServiceFramework):
_svc_name_ = "MyServiceShortName"
_svc_display_name_ = "My Service Long Fancy Name!"
_svc_description_ = "THis is what my crazy little service does - aka a DESCRIPTION! WHoa!"
def __init__(self, args):
win32serviceutil.ServiceFramework.__init__(self, args)
self.hWaitStop = win32event.CreateEvent(None, 0, 0, None)
def SvcStop(self):
self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING)
win32event.SetEvent(self.hWaitStop)
def SvcDoRun(self):
import servicemanager
servicemanager.LogMsg(servicemanager.EVENTLOG_INFORMATION_TYPE,servicemanager.PYS_SERVICE_STARTED,(self._svc_name_, ''))
self.timeout = 1000 #1 second
# This is how long the service will wait to run / refresh itself (see script below)
while 1:
# Wait for service stop signal, if I timeout, loop again
rc = win32event.WaitForSingleObject(self.hWaitStop, self.timeout)
# Check to see if self.hWaitStop happened
if rc == win32event.WAIT_OBJECT_0:
# Stop signal encountered
servicemanager.LogInfoMsg("SomeShortNameVersion - STOPPED!") #For Event Log
break
else:
try:
handle = open('c:/windows/temp/outx1.txt', "a")
handle.write('%s \n' % ('tst svc'))
handle.close()
except:
pass
def ctrlHandler(ctrlType):
return True
if __name__ == '__main__':
win32api.SetConsoleCtrlHandler(ctrlHandler, True)
win32serviceutil.HandleCommandLine(aservice)
}}}
== Logging ==
Adapted from http://docs.python.org/2/howto/logging-cookbook.html#logging-to-multiple-destinations
{{{#!highlight python
import logging
logging.basicConfig(level=logging.DEBUG, \
format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s', \
datefmt='%Y-%m-%d %H:%M:%S %z', \
filename='/tmp/myapp.log', \
filemode='a')
#log to console
console = logging.StreamHandler()
console.setLevel(logging.INFO)
formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
console.setFormatter(formatter)
logging.getLogger('').addHandler(console)
logging.info('Jackdaws love my big sphinx of quartz.')
#other loggers
logger1 = logging.getLogger('myapp.area1')
logger2 = logging.getLogger(__name__)
logger1.debug('Quick zephyrs blow, vexing daft Jim.')
logger1.info('How quickly daft jumping zebras vex.')
logger2.warning('Jail zesty vixen who grabbed pay from quack.')
logger2.error('The five boxing wizards jump quickly.')
}}}
Copied from http://docs.python.org/2/howto/logging-cookbook.html#configuration-server-example
Logging configurable on runtime, receiving new parameters by socket
Server:
{{{#!highlight python
import logging
import logging.config
import time
import os
# read initial config file
logging.config.fileConfig('logging.conf')
# create and start listener on port 9999
t = logging.config.listen(9999)
t.start()
logger = logging.getLogger('simpleExample')
try:
# loop through logging calls to see the difference
# new configurations make, until Ctrl+C is pressed
while True:
logger.debug('debug message')
logger.info('info message')
logger.warn('warn message')
logger.error('error message')
logger.critical('critical message')
time.sleep(5)
except KeyboardInterrupt:
# cleanup
logging.config.stopListening()
t.join()
}}}
Client:
{{{#!highlight python
#!/usr/bin/env python
import socket, sys, struct
with open(sys.argv[1], 'rb') as f:
data_to_send = f.read()
HOST = 'localhost'
PORT = 9999
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print('connecting...')
s.connect((HOST, PORT))
print('sending config...')
s.send(struct.pack('>L', len(data_to_send)))
s.send(data_to_send)
s.close()
print('complete')
}}}
== Logging with date rotation and email ==
{{{#!highlight python
import logging
from logging.handlers import TimedRotatingFileHandler
from logging.handlers import SMTPHandler
class Logger(object):
def __init__(self):
loggerName='appx'
logFormatter = logging.Formatter('[%(asctime)s %(name)-12s %(levelname)-8s] %(message)s',datefmt='%Y-%m-%d %H:%M:%S %z')
rotatingLogHandler = TimedRotatingFileHandler('%s.log'%(loggerName),when='midnight',utc=True)
rotatingLogHandler.setFormatter(logFormatter)
rotatingLogHandler.setLevel(logging.DEBUG)
smtpLogHandler = SMTPHandler(mailhost='hostx.com', fromaddr='mail@hostx.com', toaddrs='dest@hostx.com', subject=loggerName, \
credentials=('accountx','12345678'), secure=None)
smtpLogHandler.setFormatter(logFormatter)
smtpLogHandler.setLevel(logging.WARNING)
self.logger = logging.getLogger(loggerName)
self.logger.addHandler(rotatingLogHandler)
self.logger.addHandler(smtpLogHandler)
self.logger.setLevel(logging.DEBUG)
def debug(self,m):
self.logger.debug(m)
def info(self,m):
self.logger.info(m)
def warning(self,m):
self.logger.warning(m)
def error(self,m):
self.logger.error(m)
def critical(self,m):
self.logger.critical(m)
}}}
== pytz - World Timezone Definitions for Python ==
{{{#!highlight python
import pytz
import datetime
#fmt = '%Y-%m-%d %H:%M:%S %Z%z'
london=pytz.timezone('Europe/London')
lisbon=pytz.timezone('Europe/Lisbon')
paris =pytz.timezone('Europe/Paris')
utc = pytz.timezone('UTC')
berlin = pytz.timezone('Europe/Berlin')
print
dtx = datetime.datetime(2002, 12, 27, 12, 0, 0,tzinfo=utc )
print
print 'UTC ' , dtx
print 'London ',dtx.astimezone(london)
print 'Lisbon ',dtx.astimezone(lisbon)
print 'Paris ',dtx.astimezone(paris)
print 'Berlin ',dtx.astimezone(berlin)
print
dty = datetime.datetime(2002, 8, 27, 13, 0, 0,tzinfo=utc )
print 'UTC ',dty
print 'London ',dty.astimezone(london)
print 'Lisbon ',dty.astimezone(lisbon)
print 'Paris ',dty.astimezone(paris)
print 'Berlin ',dty.astimezone(berlin)
}}}
== Sort example ==
{{{#!highlight python
class Acme(object):
def __init__(self,valuex):
self.valuex=valuex
def __cmp__(self, other):
if self.valuex==other.valuex:
return 0
if self.valuex>other.valuex:
return 1
if self.valuex>> import testex
Traceback (most recent call last):
File "", line 1, in
ImportError: No module named testex
>>> import sys
>>> sys.path.append('/tmp') # add /tmp to modules paths
>>> testex.test1()
Allright !!!!
}}}
By default on Linux systems, modules are also searched in '''~/.local/pythonXX.YY/site-packages'''. If the file testex.py would exist, it would also be used without being necessary to add the folder /tmp to the '''sys.path''' . For the user vitor and python 2.7 the path would be '''/home/vitor/.local/lib/python2.7/site-packages''' .
== Math ==
{{{#!highlight python
# round float to 6 decimal places
nr=1.23456789
print round(nr,6)
# round float to 4 decimal places
nr=1.23456789
print round(nr,4)
}}}
== SMTP ==
{{{#!highlight python
import smtplib
class Smtp(object):
def __init__(self,server,port,user,passx,appName):
self.server=server
self.port=port
self.user=user
self.passx=passx
self.appName=appName
def send(self,fromx,tox,subjectx,contentType,body):
s=smtplib.SMTP()
s.connect(self.server,self.port)
s.ehlo(self.appName)
s.login(self.user,self.passx)
msg='From: %s\r\nTo: %s\r\nSubject: %s\r\nContent-Type: %s\r\n\r\n%s'%(fromx,tox,subjectx,contentType,body)
s.sendmail(fromx,tox,msg)
s.quit()
s=Smtp('mail.example.org',25,'norep@example.org','12345678','TestApp')
# content types: text/plain text/html
s.send('norep@example.org',['user1@example.org','user2@example.org'],'Subject','text/plain','Body mail')
}}}
== JSON serializable ==
{{{#!highlight python
from json import JSONEncoder
import json
class EncoderJSON(JSONEncoder):
def default(self, o):
return o.getJSONDict()
class Acme(object):
def __init__(self,paramx,valuex):
self.paramx=paramx
self.valuex=valuex
def getJSONDict(self):
return {'paramx':self.paramx ,'valuex':self.valuex}
def __repr__(self):
return '%s %s %s'%(self.paramx ,self.valuex)
if __name__=='__main__':
listx=[]
listx.append(Acme('p1','v1'))
listx.append(Acme('p2','v2'))
# json.dumps likes lists and dictionaries
print( json.dumps(listx,cls=EncoderJSON) )
# output [{"valuex": "v1", "paramx": "p1"}, {"valuex": "v2", "paramx": "p2"}]
}}}
== Decorators ==
http://simeonfranklin.com/blog/2012/jul/1/python-decorators-in-12-steps/
Wraps functions with functionality, before, after , changes parameters of the decorated function.
{{{#!highlight python
#decorator logger
def logger(func):
def inner(*args, **kwargs): # step 1
print "Arguments were: %s, %s" % (args, kwargs)
return func(*args, **kwargs) # step 2
return inner
@logger
def foo1(x, y=1):
return x * y
if __name__=='__main__':
foo1(2,2)
}}}
{{{#!highlight python
import sys
from os import path
#decorator adder
def add_one_args(decoratedFunction):
def interceptor(*args, **kwargs): # step 1
print "Arguments were: %s, %s" % (args, kwargs)
index=0
new_args=[]
# change input
isnotint=False
for arg in args:
if isinstance(arg,int):
new_args.append(arg+1)
else:
isnotint=True
index=index+1
if isnotint==False:
args=tuple(new_args)
decoratedFuncReturn = decoratedFunction(*args, **kwargs) # step 2
# change output
decoratedFuncReturn = decoratedFuncReturn * 2
return decoratedFuncReturn
return interceptor
@add_one_args
def foo1(x, y=1):
print('Got arguments in foo1 %d %d'%(x,y))
mul = x * y
print('Multiplication result inside function %d'%(mul))
return mul
if __name__=='__main__':
print( foo1(2,2) )
print( sys.path )
print( sys.prefix )
print( sys.exec_prefix )
here = path.abspath(path.dirname(__file__))
print(here)
}}}
== Dictionaries ==
{{{#!highlight python
Type "help", "copyright", "credits" or "license" for more information.
a={} #create dictionary
if 'keyx' in a: print 'ok' #check if key keyx exists
a['keyx']=1 # create key keyx with value 1
if 'keyx' in a: print 'ok' #checks keyx existence
a['key2']={} # create key key2
if 'keyx' in a['key2']: print 'ok' # check if keyx exists in key2
a['key2']['keyx']=3 # create keyx inside key2
if 'keyx' in a['key2']: print 'ok'
}}}
== Exceptions ==
Example 1
{{{#!highlight python
def dummyMethod(datax):
try:
if 'key1' in datax:
key1 = datax['key1']
if 'key2' in key1:
key2 = dvi['key2']
print('key2 is %s '%(key2))
except Exception,ex:
print('Error in dummyMethod %s'%( str(ex) ) )
}}}
== Install pip ==
* easy_install pip
== Regular expressions ==
{{{#!python
import re
listx=['aa12.txt','a123sss.txt','bs11bb.txt','123aaaa.sql','a12.txt','aaaa12','20ghj','6657']
for item in listx:
res = re.match('^(\D+)(\d+)(\D+)$',item)
if res!=None:
decimal = int(res.group(2)) + 1
print('A: mv %s %s%d%s'%(item , res.group(1),decimal , res.group(3) ))
res = re.match('^(\d+)(\D+)$',item)
if res!=None:
decimal = int(res.group(1)) + 1
print('B: mv %s %d%s'%(item , decimal,res.group(2)))
res = re.match('^(\D+)(\d+)$',item)
if res!=None:
decimal = int(res.group(2)) + 1
print('C: mv %s %s%d'%(item , res.group(1),decimal))
res = re.match('^(\d+)$',item)
if res!=None:
decimal = int(res.group(1)) + 1
print('D: mv %s %d'%(item , decimal))
'''
#ouput
python addNumber.py
A: mv aa12.txt aa13.txt
A: mv a123sss.txt a124sss.txt
A: mv bs11bb.txt bs12bb.txt
B: mv 123aaaa.sql 124aaaa.sql
A: mv a12.txt a13.txt
C: mv aaaa12 aaaa13
B: mv 20ghj 21ghj
D: mv 6657 6658
'''
}}}
== Command line arguments ==
* import sys
{{{#!highlight python
import sys
# ...
if __name__=='__main__':
intArgA = int(sys.argv[1])
intArgB = int(sys.argv[2])
intArgC = int(sys.argv[3])
}}}
== Run python code in shell without source code file .py ==
{{{#!highlight sh
echo "" | xargs -i echo -e "strx='{}'\nsplitted = strx.split(' ')\nfor spl in splitted:\n\tif 'msgId' in spl:\n\t\tprint spl.split('=')[1]" | python
}}}
{{{#!highlight python
strx='{}' # where xargs value is used
splitted = strx.split(' ')
for spl in splitted:
if 'msgId' in spl:
print spl.split('=')[1]
}}}
== Alias identifier inside module ==
{{{
>>> from json import dumps as jsonDumps
>>> jsonDumps({'key':'value'})
'{"key": "value"}'
>>> print jsonDumps({'key':'value' , 'key2':1234})
{"key2": 1234, "key": "value"}
>>>
}}}
== Execute process using subprocess ==
{{{#!highlight python
import subprocess
if __name__=='__main__':
try:
args=[]
args.append('ls')
args.append('/tmpx')
out = subprocess.check_output(args, stderr=subprocess.STDOUT, shell=False)
print( out )
except subprocess.CalledProcessError as ex1:
print("Exception command: %s"%(ex1.cmd) )
print("Exception code: %s"%(ex1.returncode) )
print("Exception output: %s"%(ex1.output) )
except Exception as ex2:
print("General exception %s"%(ex2.message) )
}}}
== Recursion ==
{{{#!highlight python
def factorial(n):
if n > 0: return n * factorial(n-1)
else: return 1
def fibo(n):
if n==0: return 0
if n==1: return 1
if n>1: return fibo(n-1) + fibo(n-2)
def sum(idx,lista):
if idx<0: return 0
if idx>=0: return lista[idx] + sum(idx-1,lista)
if __name__=='__main__':
print( factorial(4) )
print( fibo(3) )
lst=[1,2,3,4]
print( sum(len(lst)-1,lst) )
}}}
== Python3 virtual environment ==
* https://packaging.python.org/tutorials/installing-packages/#creating-virtual-environments
Python “Virtual Environments” allow Python packages to be installed in an isolated location for a particular application, rather than being installed globally.
You can deactivate a virtual environment by typing “deactivate” in your shell.
{{{#!highlight bash
sudo apt-get install python3-venv
python3 -m venv testVenv
source testVenv/bin/activate
pip install --upgrade pip
pip install -i https://testpypi.python.org/pypi vbhelloworld
pip uninstall vbhelloworld
}}}
* https://docs.python.org/3/library/venv.html#module-venv
When a virtual environment is active (i.e., the virtual environment’s Python interpreter is running), the attributes sys.prefix and sys.exec_prefix point to the base directory of the virtual environment, whereas sys.base_prefix and sys.base_exec_prefix point to the non-virtual environment Python installation which was used to create the virtual environment.
If a virtual environment is not active, then sys.prefix is the same as sys.base_prefix and sys.exec_prefix is the same as sys.base_exec_prefix (they all point to a non-virtual environment Python installation).
== List Comprehensions ==
{{{#!highlight python
squares = [x**2 for x in range(10)]
# squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
sequence = [x for x in range(1,9)]
# sequence [1, 2, 3, 4, 5, 6, 7, 8]
range(10)
# [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
squares = [x**2 for x in range(10) if x<= 4]
# squares [0, 1, 4, 9, 16]
}}}
== Python 2 virtual env ==
{{{#!highlight sh
# in windows with powershell
cd ~
pip install virtualenv --user
# add the scripts folder to the user path c:\users\userx\AppData\Roaming\Python\Scripts
# using cmd
cd %HOME_PATH%
mkdir tmp
cd tmp
virtualenv.exe test_env
cd test_env
Scripts\activate.bat
}}}
{{{#!highlight python
import sys
sys.path
}}}
== Generator functions yield ==
{{{#!highlight python
#test yield
def factorial(val):
v=val
res=1
while v>1:
res=res*v
v=v-1
yield None # v
yield res
if __name__ == "__main__":
for i in factorial(3):
print(i)
f = factorial(4)
iterate=True
while iterate:
try:
print( f.next() )
#print( next(f) )
except StopIteration as ex:
iterate=False
}}}
'''Output:'''
{{{#!highlight bash
python test_yeld.py
None
None
6
None
None
None
24
}}}
== XML parse with minidom ==
* https://docs.python.org/2/library/xml.dom.minidom.html
{{{#!highlight python
from xml.dom import minidom
print("Hello world")
a="aaaabbcc"
doc = minidom.parseString(a) # return document
tags = doc.getElementsByTagName("b")
for t in tags:
print(t.firstChild.nodeValue)
}}}
== Environment variable ==
{{{#!highlight python
import os
print(os.environ)
}}}
== XSD and objectify XML ==
'''test.py'''
{{{#!highlight python
from lxml import objectify
from StringIO import StringIO
from lxml import etree
f = open('test.xsd')
xsddata=''
for line in f:
xsddata = xsddata + line
f.close()
xmlschema_doc = etree.parse(StringIO(xsddata))
xmlschema = etree.XMLSchema(xmlschema_doc)
print xmlschema
parser = objectify.makeparser(schema=xmlschema)
xml = "test"
a = objectify.fromstring(xml, parser)
print(a.b)
}}}
'''test.xsd'''
{{{#!highlight xml
}}}
'''Other example ....'''
'''acme.xsd'''
{{{highlight xml
}}}
'''test.xsd'''
{{{#!highlight xml
}}}
'''acme.py'''
{{{#!highlight python
from lxml import objectify
from StringIO import StringIO
from lxml import etree
import os
f = open('acme.xsd')
xsddata=''
for line in f:
xsddata = xsddata + line
f.close()
xmlschema = etree.XMLSchema(etree.parse(StringIO(xsddata)))
xml = """
cccc
hhjjkk
1234
"""
doc = etree.fromstring(xml, etree.XMLParser(schema=xmlschema) )
# https://lxml.de/api/lxml.etree._Element-class.html
bNode = doc.getchildren()[0]
otherNode = doc.getchildren()[2]
print bNode.text
print otherNode.text
}}}
== Debugger ==
{{{#!highlight python
# python test.py
# DEBUG=on python test.py
import os
# ....
if 'DEBUG' in os.environ:
# breakpoint
import pdb; pdb.set_trace()
# commands
# c continue
# q quit
# n next
# l list
# s step
}}}