For single dimensions arrays:
a2 = a[:]
non-scalers within array will be copied as references. Does the same thing as copy.copy()
For multi dimension arrays:
import copy
a2 = copy.deepcopy(a)
non-scalers within array will be cloned as new objects
Archive for the ‘Python’ Category
Cloning arrays in python
Sunday, April 11th, 2010Python eval
Monday, September 7th, 2009Generally, just use ‘exec’ statement instead of the ‘eval’ function
v = 1
exec 'v = 2'
print v
Python eval is a function meaning it doesn’t allow setting of variables. Usage is:
x = 1
print eval(‘x+1′)
Python – Getting dot to match newlines as well
Thursday, July 23rd, 2009re.DOTALL / re.S – means dot will match newlines
re.MULTILINE / re.M – means that ^$ will only match start and end of string. By default they match start and end of each line
match = re.search(r'^(.+lorem ipsum)(.+)(donor kebab.+)$', s, re.DOTALL + re.MULTILINE)
Python MySQL utf connection + dictionary recordsets
Tuesday, July 14th, 2009# -*- coding: utf-8 -*-
import MySQLdb, MySQLdb.cursors
db_connection = MySQLdb.connect(user="root", passwd="pass",
db="mydb", cursorclass = MySQLdb.cursors.DictCursor,
use_unicode = True)
db = db_connection.cursor()
# assuming that id=1271 has a val that has utf "µ" in it
sql = """
SELECT *
FROM vals
WHERE id = 1271
""" % ()
db.execute(sql)
r = db.fetchall()[0]
val = r['val']
print val
print type(val)
Python unicode + xml.dom.minidom + write to file
Tuesday, July 14th, 2009# -*- coding: utf-8 -*-
import xml.dom.minidom, codecs
impl = xml.dom.minidom.getDOMImplementation()
dom = impl.createDocument(None, "root", None)
root_el = dom.documentElement
ascii_el = dom.createElement('ascii')
root_el.appendChild(ascii_el)
ascii_el.appendChild(dom.createTextNode('abc'))
utf_el = dom.createElement('utf')
root_el.appendChild(utf_el)
utf_el.appendChild(dom.createTextNode(unicode('µ 6000', 'utf-8')))
# There's a couple of ways of dealing with output:
if True:
# Will write a utf encoded file without BOM
# <?xml version="1.0"?>
# Will print "µ" to the console
# type(xmlstr) == 'unicode' i.e. unicode string
xmlstr = dom.toxml()
f = codecs.open('utf_test.xml', 'w', 'utf-8')
f.write(xmlstr)
f.close()
print xmlstr
print type(xmlstr)
else:
# Will write a utf encoded file without BOM (same as above)
# <?xml version="1.0" encoding="utf-8"?>
# Will print "??" to the console
# type(xmlstr) == 'str' -- i.e. byte string
xmlstr = dom.toxml('utf-8')
f = open('utf_test.xml', 'w')
f.write(xmlstr)
f.close()
print xmlstr
print type(xmlstr)
Python – pretty dictionary access for objects
Sunday, June 28th, 2009Instead of hash like access i.e. val = hash['key']
You can achieve a prettier val = obj.key :
class Obj:
..def add(self, k, v):
....self.__dict__[k] = v
o = Obj()
o.add(key, val)