Does anyone know of a memory efficient way to generate very large xml files (e.g. 100-500 MiB) in Python?
I've been utilizing lxml, but memory usage is through the roof.
I am trying to get the response codes from Mechanize in python. While I am able to get a 200 status code anything else isn't returned (404 throws and exception and 30x is ignored). Is there a way to get the original status code?
Thanks
The greenlet package is used by gevent and eventlet for asynchronous IO. It is written as a C-extension and therefore doesn't work with Jython or IronPython. If performance is of no concern, what is the easiest approach to implementing the greenlet API in pure Python.
A simple example:
def test1():
print 12
gr2.switch()
print 34
def test2():
print 56
gr1.switch()
print 78
gr1 = greenlet(test1)
gr2 = greenlet(test2)
gr1.switch()
Should print 12, 56, 34 (and not 78).
I am pretty new to python and I discovered by myself that I can create a list of function and call with a for loop.
example:
def a(args):
print "A"
def b(args):
print "B"
def c(args):
print "C " + str(args)
functions = [a,b,c]
for i in functions:
i(1)
So, my question is: is there any good practice or elegant way to use list of functions and what is a good use of all this? (do have a particular name the "list of functions"?)
thank you
In Javascript I can do this:
function A(x) { return x || 3; }
This returns 3 if x is a "non-truthful" value like 0, null, false, and it returns x otherwise. This is useful for empty arguments, e.g. I can do A() and it will evaluate as 3.
Does Python have an equivalent? I guess I could make one out of the ternary operator a if b else c but was wondering what people use for this.
Is there some relatively simple way to programmatically include source code lines to python logger report. For example...
import logging
def main():
something_is_not_right = True
logging.basicConfig(level=logging.DEBUG,
format=('%(filename)s: '
'%(levelname)s: '
'%(funcName)s(): '
'%(lineno)d:\t'
'%(message)s')
)
if something_is_not_right == True:
logging.debug('some way to get previous line of source code here?')
So that output would look like this.
example.py: DEBUG: main(): 14: if something_is_not_right == True:
I'm looking for a way in python to find out which type of file system is being used for a given path. I'm wanting to do this in a cross platform way. On linux I could just grab the output of df -T but that won't work on OSX or windows.
Hi,
I need to compare two files and redirect the different lines to third file. I know using diff command i can get the difference . But, is there any way of doing it in python ? Any sample code will be helpful
I am creating an application that lets users login using Google, Facebook and the website's native login. The site is being built in Python / Django.
What would be the best way to handle login, session management and user authentication?
I do not want to use the in-built Django user management. I am using Django very sparingly(URLs, templates)
Hi
I wrote a matlab code (that easily could be implimented as a function) that convert a series of BMPs to avi. I want a python program to call to this program/function. how do I do it?
thanks
I downloaded a webpage in my python script.
In most cases, this works fine.
However, this one had a response header: GZIP encoding, and when I tried to print the source code of this web page, it had all symbols in my putty.
How do decode this to regular text?
What's the best way of getting the last item from an iterator in Python 2.6? For example, say
my_iter = iter(range(5))
What is the shortest-code / cleanest way of getting 4 from my_iter?
I could do this, but it doesn't seem very efficient:
[x for x in my_iter][-1]
Using python and wsgiref.handlers, I can get a single variable from a form with self.handler.request.get(var_name), but how do I iterate through all form variables, be they from GET and POST? Is it something like this?
for field in self.handler.request.fields:
value = self.handler.request.get(field)
Again, it should include both fields included in the POST and fields from the query string, as in a GET request.
Thanks in advance folks...
How are lists in python stored internally? Is it an array? A linked list? Something else?
Or does the interpreter guess at the right structure for each instance based on length, etc.
If the question is implementation dependent, what about the classic CPython?
Hi
I am trying to perform a 2d convolution in python using numpy
I have a 2d array as follows with kernel H_r for the rows and H_c for the columns
data = np.zeros((nr, nc), dtype=np.float32)
#fill array with some data here then convolve
for r in range(nr):
data[r,:] = np.convolve(data[r,:], H_r, 'same')
for c in range(nc):
data[:,c] = np.convolve(data[:,c], H_c, 'same')
It does not produce the output that I was expecting, does this code look OK
Thanks
how can I use wild cars like '*' when getting a list of files inside a directory in Python? for example, I want something like:
os.listdir('foo/*bar*/*.txt')
which would return a list of all the files ending in .txt in directories that have bar in their name inside of the foo parent directory.
how can I do this?
thanks.
Given a PyObject* pointing to a python object, how do I invoke one of the object methods? The documentation never gives an example of this:
PyObject* obj = ....
PyObject* args = Py_BuildValue("(s)", "An arg");
PyObject* method = PyWHATGOESHERE(obj, "foo");
PyObject* ret = PyWHATGOESHERE(obj, method, args);
if (!ret) {
// check error...
}
This would be the equivalent of
>>> ret = obj.foo("An arg")
Format is like:
CHINA;2002-06-25 00:00:00.000;5,60
CHINA;2002-06-26 00:00:00.000;5,32
CHINA;2002-06-27 00:00:00.000;5,31
and I try to use Python's CSV tools to parse it but cannot understand the paragraph, source:
And while the module doesn’t directly support parsing strings, it can easily be done:
import csv
for row in csv.reader(['one,two,three']):
print row
Could someone clarify the line ['one,two,three']? How would you use it with format A;B;C?
I am using Python with PLY to parse LISP-like S-Expressions and when parsing a function call there can be zero or more arguments. How can I put this into the yacc code. This is my function so far:
def p_EXPR(p):
'''EXPR : NUMBER
| STRING
| LPAREN funcname [EXPR] RPAREN'''
if len(p) == 2:
p[0] = p[1]
else:
p[0] = ("Call", p[2], p[3:-1])
I need to replace "[EXPR]" with something that allows zero or more EXPR's. How can I do this?
Hey, here's a dumb question: how can I set an object property given its name in a string. I have a dictionary being passed to me and I wish to transfer its values into namesake properties using code like this:
for entry in src_dict:
if entry.startswith('can_'):
tgt_obj[entry] = src_dict_profile[entry]
I'm still a bit of a noob with Python so would appreciate some help.
- dave.
how to traverse a binary decision tree using python language.
given a tree,i want know how can we travesre from root to required leaf
the feature of the required leaf are given in an dictionary form assume and have to traverse from root to leaf answering the questions at each node with the details given in feature list..
the decision tree node has format ((question)(left tree)(right tree))
while traversing it should answer question at each node and an choose left or right and traverse till leaf?
I am creating a sort of "Command line" in Python. I already added a few functions, such as changing login/password, executing, etc., But is it possible to browse files in the directory that the main file is in with a command/module, or will I have to make the module myself and use the import command? Same thing with changing directories to view, too.