Quick and dirty scripting with Python

Quick and dirty scripting with Python

http://xkcd.com/353/

I came home from work today and, instead of taking a nap (something that would have come in really handy) or playing Mass Effect 2, I started coding a couple of scripts to help me organising some files that I've got in several Micro SD cards.

Keep in mind that I've omitted the imports, "const-like" vars declarations and the if __name__=="__main__" statement for the sake of brevity.

The first one just lists the files and subdirectories from a given path, and then it saves it to a text file. Python also provides the function os.walk (or the deprecated os.path.walk), but I got it into my head that I wanted to indent the files according to the depth from the root path and the easiest way to accomplish this was using os.listdir, which worked as a charm =)

def extract_dir_files(arg, dirname):     dir_str= "%s/%s/\n" % (" "*arg[0],os.path.split(dirname)[1])     arg[1].write(dir_str) #os.listdir just returns a list containing all files and directories #contained within the path 'dirname'     for item in os.listdir(dirname):         new_path = os.path.join(dirname,item)         args = [arg[0]+1,arg[1]]         if os.path.isdir(new_path): #The child directories will make recursive calls #until the root_path directory has been completely #parsed             extract_dir_files(args,new_path)         else:             name,ext = os.path.splitext(item)             #do not write out the files having one of the #extensions specified in IGNORE_EXT             if ext not in IGNORE_EXT:                 file_str = "%s-%s\n" % (" "*(arg[0]+1),item)                 arg[1].write(file_str)                 print(file_str)     def main():     root_path = os.path.join(DRIVE_LETTER,ROOT_PATH)     with open(OUTPUT_FILE, 'a') as f:         f.write("*"*PAD_NUM+"\n") #args[0] will hold the value of the current depth in the dir. #hierarchy; args[1], the file object         args = [0,f]         extract_dir_files(args,root_path)         f.write("*"*PAD_NUM+"\n")

The second one gets the HTML contents of a given URL which are parsed to a DOM-like object. After that, all that it's left is to extract the data of interest and do whatever you want. In my case, I decided to write them to a *.CSV file for future use. I used the library available at http://www.boddie.org.uk/python/libxml2dom.html

It was pretty easy to use, and it allowed for DOM-like processing of HTML pages, which aren't generally well-formed. This causes complaints and exceptions when using better known Python DOM libraries.

def main(): #URL returns a list of links, of which I'll only be #interested in their text values. #FROM and TO are the values I want to pass to the query #as GET parameters.     with contextlib.closing(urllib.urlopen(URL%(FROM,TO))) as url:         encoding = url.headers['Content-type'].split('charset=')[1]         contents = url.read().decode(encoding).encode('utf-8')     doc = libxml2dom.parseString(contents,html=1)     links = doc.getElementsByTagName("a")     results = []     for l in links:         release = l.childNodes[0].nodeValue         #...then do whatever you want with it :P