Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>To speed up your existing code measurably, add <code>def main():</code> before the assignment to <code>tokenList</code>, indent everything after that 4 spaces, and at the end put the usual idiom</p> <pre><code>if __name__ == '__main__': main() </code></pre> <p>(The guard is not actually necessary, but it's a good habit to have nevertheless since, for scripts with reusable functions, it makes them importable from other modules).</p> <p>This has little to do with "object oriented" anything: it's simply faster, in Python, to keep all your substantial code in functions, <em>not</em> as top-level module code.</p> <p>Second speedup, change <code>cleanedInput</code> into a list, i.e., its first assignment should be <code>= []</code>, and wherever you now have <code>+=</code>, use <code>.append</code> instead. At the end, <code>''.join(cleanedInput)</code> to get the final resulting string. This makes your code take linear time as a function of input size (<code>O(N)</code> is the normal way of expressing this) while it currently takes quadratic time (<code>O(N squared)</code>).</p> <p>Then, correctness: the two statements right after <code>continue</code> never execute. Do you need them or not? Remove them (and the <code>continue</code>) if not needed, remove the <code>continue</code> if those two statements are actually needed. And the tests starting with <code>if diff</code> will fail dramatically unless the previous <code>if</code> was executed, because <code>diff</code> would be undefined then. Does your code as posted perhaps have indentation errors, i.e., is the indentation of what you posted different from that of your actual code?</p> <p>Considering these important needed enhancements, and the fact that it's hard to see what advantage you are pursuing in making this tiny code OO (and/or modular), I suggest clarifying the indenting / correctness situation, applying the enhancements I've proposed, and leaving it at that;-).</p> <p><strong>Edit</strong>: as the OP has now applied most of my suggestions, let me follow up with one reasonable way to hive off most functionality to a class in a separate module. In a new file, for example <code>foobar.py</code>, in the same directory as the original script (or in <code>site-packages</code>, or elsewhere on <code>sys.path</code>), place this code:</p> <pre><code>def token_of(line): return line.partition(':')[-1].strip() class FileParser(object): def __init__(self, filename): self.tokenList = open(filename, 'r') def cleaned_input(self): cleanedInput = [] prevLine = 0 for line in self.tokenList: if line.startswith('LINE:'): lineNo = int(token_of(line)) diff = lineNo - prevLine - 1 cleanedInput.append('\n' * (diff if diff&gt;1 else diff+1)) prevLine = lineNo else: cleanedLine = token_of(line) cleanedInput.append(cleanedLine + ' ') return cleanedInput </code></pre> <p>Your main script then becomes just:</p> <pre><code>import sys import foobar def main(): thefile = foobar.FileParser(sys.argv[1]) print thefile.cleaned_input() if __name__ == '__main__': main() </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POMaking a Python script Object-Oriented
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USAlex Martelli
    1. USAlex Martelli
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POMaking a Python script Object-Oriented
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    1. COTo expand on one of Alex's points a little: in Python, strings are immutable. `s += 'abc'` makes a completely new copy of `s` with `abc` appended. So if you're building a long string with concatenation, you're copying an ever-growing string over and over again. Appending items to a list (or using the `StringIO` module) and then doing a single `join` at the end avoids this.
      singulars
      1. PO
      1. USRobert Rossney
    2. COThanks for those comments Alex. Yes there was indentation errors from when I pasted it in. I've fixed that now to reflect what I'm looking at in my IDE. The reason why I would like this code to become modular is because the program will eventually be a recursive-descent parser, so I would like to split things up for simplicity.
      singulars
      1. PO
      1. USgreenie
    3. CO@greenie, thanks for fixing the indentation, but the problems I pointed out (code not in a function, string +=) remain, and there are others such as the total repetition of the complex split-and-strip expression, that are **far** higher priority, to enhance this code's quality, than relegating a few lines to a method rather than a function. First things first!-)
      singulars
      1. PO
      1. USAlex Martelli
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload