Simply use [`\1`][1] instead of `$1`:

    In [1]: import re
    
    In [2]: method = &#39;images/:id/huge&#39;
    
    In [3]: re.sub(r&#39;(:[a-z]+)&#39;, r&#39;&lt;span&gt;\1&lt;/span&gt;&#39;, method)
    Out[3]: &#39;images/&lt;span&gt;:id&lt;/span&gt;/huge&#39;

Also note the use of [raw strings][2] (`r&#39;...&#39;`) for regular expressions. It is not mandatory but removes the need to escape backslashes, arguably making the code slightly more readable.


  [1]: http://docs.python.org/library/re.html#regular-expression-syntax
  [2]: https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals

Use `\1` instead of `$1`.

&gt; \number Matches the contents of the group of the same number.

http://docs.python.org/library/re.html#regular-expression-syntax

A backreference to the whole match value is `\g&lt;0&gt;`, see [`re.sub` documentation](https://docs.python.org/3/library/re.html#re.sub):

&gt; The backreference `\g&lt;0&gt;` substitutes in the entire substring matched by the RE.


See the [Python demo][1]:
```python
import re
method = &#39;images/:id/huge&#39;
print(re.sub(r&#39;:[a-z]+&#39;, r&#39;&lt;span&gt;\g&lt;0&gt;&lt;/span&gt;&#39;, method))
# =&gt; images/&lt;span&gt;:id&lt;/span&gt;/huge
```
If you need to perform a case insensitive search, add `flag=re.I`:
```python
re.sub(r&#39;:[a-z]+&#39;, r&#39;&lt;span&gt;\g&lt;0&gt;&lt;/span&gt;&#39;, method, flags=re.I)
```

  [1]: https://ideone.com/TFMUlz

For the replacement portion, Python uses `\1` the way sed and vi do, **not** `$1` the way Perl, Java, and Javascript (amongst others) do.  Furthermore, because `\1` interpolates in regular strings as the character U+0001, you need to use a raw string or \\escape it.

    Python 3.2 (r32:88445, Jul 27 2011, 13:41:33) 
    [GCC 4.0.1 (Apple Inc. build 5465)] on darwin
    Type &quot;help&quot;, &quot;copyright&quot;, &quot;credits&quot; or &quot;license&quot; for more information.
    &gt;&gt;&gt; method = &#39;images/:id/huge&#39;
    &gt;&gt;&gt; import re
    &gt;&gt;&gt; re.sub(&#39;:([a-z]+)&#39;, r&#39;&lt;span&gt;\1&lt;/span&gt;&#39;, method)
    &#39;images/&lt;span&gt;id&lt;/span&gt;/huge&#39;
    &gt;&gt;&gt; 

I have this problem, I have two divs:

    &lt;div style=&quot;width:100%; height:50px;&quot; id=&quot;div1&quot;&gt;&lt;/div&gt;
    &lt;div style=&quot;width:100%;&quot; id=&quot;div2&quot;&gt;&lt;/div&gt;

How do I make div2 occupy remaining height of the page?

How to make div occupy remaining height?

Is modal editing possible in command-line mode?

Some examples:

 - After writing `!ls ~/foo/bar` I want to `db` to delete *bar*
 - I executed the above command and now I want to change `ls` to `mv` and jump back to $

Using normal-mode motions in command-line mode in Vim

Trying to get to grips with regular expressions in Python, I&#39;m trying to output some HTML highlighted in part of a URL. My input is

    images/:id/size

my output should be

    images/&lt;span&gt;:id&lt;/span&gt;/size

If I do this in Javascript

    method = &#39;images/:id/size&#39;;
    method = method.replace(/\:([a-z]+)/, &#39;&lt;span&gt;$1&lt;/span&gt;&#39;)
    alert(method)

I get the desired result, but if I do this in Python

    &gt;&gt;&gt; method = &#39;images/:id/huge&#39;
    &gt;&gt;&gt; re.sub(&#39;\:([a-z]+)&#39;, &#39;&lt;span&gt;$1&lt;/span&gt;&#39;, method)
    &#39;images/&lt;span&gt;$1&lt;/span&gt;/huge&#39;

I don&#39;t, how do I get Python to return the correct result rather than `$1`? Is `re.sub` even the right function to do this?

re.sub replace with matched content

Trying to get to grips with regular expressions in Python, I'm trying to output some HTML highlighted in part of a URL. My input is
<pre><code class="hljs language-ruby">images/:id/size
</code></pre>
my output should be
<pre><code class="hljs language-ruby">images/&#x3C;span>:id&#x3C;/span>/size
</code></pre>
If I do this in Javascript
<pre><code class="hljs language-ini">method = 'images/:id/size';
method = method.replace(/\:([a-z]+)/, '&#x3C;span>$1&#x3C;/span>')
alert(method)
</code></pre>
I get the desired result, but if I do this in Python
<pre><code class="hljs language-python-repl">>>> method = 'images/:id/huge'
>>> re.sub('\:([a-z]+)', '&#x3C;span>$1&#x3C;/span>', method)
'images/&#x3C;span>$1&#x3C;/span>/huge'
</code></pre>
I don't, how do I get Python to return the correct result rather than <code>$1</code>? Is <code>re.sub</code> even the right function to do this?

I have read python docs about abstract base classes:

From [here][1]:
&gt; `abc.abstractmethod(function)`
&gt; A decorator indicating abstract methods.
&gt;
&gt; Using this decorator requires that the class’s metaclass is `ABCMeta` or
&gt; is derived from it. A class that has a metaclass derived from `ABCMeta`
&gt; cannot be instantiated unless all of its abstract methods and
&gt; properties are overridden.

And [here][2]

&gt; You can apply the `@abstractmethod` decorator to methods such as draw()
&gt; that must be implemented; Python will then raise an exception for
&gt; classes that don’t define the method. Note that the exception is only
&gt; raised when you actually try to create an instance of a subclass
&gt; lacking the method.

I&#39;ve used this code to test that out:

&lt;!-- language: lang-py --&gt;

    import abc

    class AbstractClass(object):
      __metaclass__ = abc.ABCMeta
      
      @abc.abstractmethod
      def abstractMethod(self):
        return
    
    class ConcreteClass(AbstractClass):
      def __init__(self):
        self.me = &quot;me&quot;

    c = ConcreteClass()
    c.abstractMethod()

The code goes fine, so I don&#39;t get it. If I type `c.abstractMethod` I get:

    &lt;bound method ConcreteClass.abstractMethod of &lt;__main__.ConcreteClass object at 0x7f694da1c3d0&gt;&gt;

What I&#39;m missing here? `ConcreteClass` *must* implement the abstract methods, but I get no exception.

  [1]: http://docs.python.org/library/abc.html
  [2]: http://docs.python.org/whatsnew/2.6.html#pep-3119-abstract-base-classes


python @abstractmethod decorator

I have a dictionary like this:

    A = {&#39;a&#39;:10, &#39;b&#39;:843, &#39;c&#39;: 39,.....}

I want to get the 5 maximum values of this dict and store a new dict with this. To get the maximum value I did:

    max(A.iteritems(), key=operator.itemgetter(1))[0:]

Perhaps it is an easy task, but I am stuck on it for a long time. Please help!!!

5 maximum values in a python dictionary

I&#39;m trying to turn a list of 2d numpy arrays into a 2d numpy array.  For example, 

    dat_list = []
    for i in range(10):
        dat_list.append(np.zeros([5, 10]))

What I would like to get out of this list is an array that is (50, 10).  However, when I try the following, I get a (10,5,10) array.

    output = np.array(dat_list)

Thoughts?

Python List of np arrays to array

I need to merge multiple dictionaries, here&#39;s what I have for instance:

    dict1 = {1:{&quot;a&quot;:{A}}, 2:{&quot;b&quot;:{B}}}

    dict2 = {2:{&quot;c&quot;:{C}}, 3:{&quot;d&quot;:{D}}

With `A` `B` `C` and `D` being leaves of the tree, like `{&quot;info1&quot;:&quot;value&quot;, &quot;info2&quot;:&quot;value2&quot;}`

There is an unknown level(depth) of dictionaries, it could be `{2:{&quot;c&quot;:{&quot;z&quot;:{&quot;y&quot;:{C}}}}}`

In my case it represents a directory/files structure with nodes being docs and leaves being files.

I want to merge them to obtain:

     dict3 = {1:{&quot;a&quot;:{A}}, 2:{&quot;b&quot;:{B},&quot;c&quot;:{C}}, 3:{&quot;d&quot;:{D}}}

I&#39;m not sure how I could do that easily with Python.

How to merge dictionaries of dictionaries?

I researched first and couldn&#39;t find an answer to my question. I am trying to run multiple functions in parallel in Python.

I have something like this:
&lt;!-- language: py --&gt;

    files.py

    import common #common is a util class that handles all the IO stuff
    
    dir1 = &#39;C:\folder1&#39;
    dir2 = &#39;C:\folder2&#39;
    filename = &#39;test.txt&#39;
    addFiles = [25, 5, 15, 35, 45, 25, 5, 15, 35, 45]

    def func1():
       c = common.Common()
       for i in range(len(addFiles)):
           c.createFiles(addFiles[i], filename, dir1)
           c.getFiles(dir1)
           time.sleep(10)
           c.removeFiles(addFiles[i], dir1)
           c.getFiles(dir1)

    def func2():
       c = common.Common()
       for i in range(len(addFiles)):
           c.createFiles(addFiles[i], filename, dir2)
           c.getFiles(dir2)
           time.sleep(10)
           c.removeFiles(addFiles[i], dir2)
           c.getFiles(dir2)
    


I want to call func1 and func2 and have them run at the same time. The functions do not interact with each other or on the same object. Right now I have to wait for func1 to finish before func2 to start. How do I do something like below:
&lt;!-- language: py --&gt;

    process.py

    from files import func1, func2
  
    runBothFunc(func1(), func2())

I want to be able to create both directories pretty close to the same time because every min I am counting how many files are being created. If the directory isn&#39;t there it will throw off my timing. 


How to run functions in parallel?

How can I convert a string either like &#39;helloThere&#39; or &#39;HelloThere&#39; to &#39;Hello There&#39; in JavaScript?

Convert camelCaseText to Title Case Text

Is there an NOT operator in Regexes?
Like in that string : `&quot;(2001) (asdf) (dasd1123_asd 21.01.2011 zqge)(dzqge) name (20019)&quot;`

I want to delete all `$[0-9a-zA-z _\.\-:]*$` but not the one where it is a year: `(2001)`.

So what the regex should return must be: `(2001) name`.

NOTE: something like `$(?![\d]){4}[0-9a-zA-z _\.\-:]*$` does not work for me (the `(20019)` somehow also matches...)

Regex not operator

Here is a regex that works fine in most regex implementations:

    (?&lt;!filename)\.js$

This matches .js for a string which ends with .js except for filename.js

Javascript doesn&#39;t have regex lookbehind. Is anyone able put together an alternative regex which achieve the same result and works in javascript?

Here are some thoughts, but needs helper functions. I was hoping to achieve it just with a regex:
http://blog.stevenlevithan.com/archives/mimic-lookbehind-javascript




javascript regex - look behind alternative?

Let&#39;s say I have a string which contains this:

    HelloxxxHelloxxxHello

I compile a pattern to look for &#39;Hello&#39;

    Pattern pattern = Pattern.compile(&quot;Hello&quot;);
    Matcher matcher = pattern.matcher(&quot;HelloxxxHelloxxxHello&quot;);

It should find three matches. How can I get a count of how many matches there were?

I&#39;ve tried various loops and using the `matcher.groupCount()` but it didn&#39;t work.

How can I count the number of matches for a regex?

I&#39;m trying to parse a document that has reference numbers littered throughout it.

&gt; Text text text {4:2} more incredible text {4:3} much later on
&gt; {222:115} and yet some more text.

The references will always be wrapped in brackets, and there will always be a colon between the two. I wrote an expression to find them.

    {[0-9]:[0-9]}

However, this obviously fails the moment you come across a two or three digit number, and I&#39;m having trouble figuring out what that should be. There won&#39;t ever be more than 3 digits {999:999} is the maximum size to deal with.

Anybody have an idea of a proper expression for handling this?

RegEx - Match Numbers of Variable Length

I would like to use more than one flag with the `re.findall` function. More specifically, I would like to use the `IGNORECASE` and `DOTALL` flags at the same time.

    x = re.findall(r&#39;CAT.+?END&#39;, &#39;Cat \n eND&#39;, (re.I, re.DOTALL))
    
Error :

    Traceback (most recent call last):
      File &quot;&lt;pyshell#78&gt;&quot;, line 1, in &lt;module&gt;
        x = re.findall(r&#39;CAT.+?END&#39;,&#39;Cat \n eND&#39;,(re.I,re.DOTALL))
      File &quot;C:\Python27\lib\re.py&quot;, line 177, in findall
        return _compile(pattern, flags).findall(string)
      File &quot;C:\Python27\lib\re.py&quot;, line 243, in _compile
        p = sre_compile.compile(pattern, flags)
      File &quot;C:\Python27\lib\sre_compile.py&quot;, line 500, in compile
        p = sre_parse.parse(p, flags)
      File &quot;C:\Python27\lib\sre_parse.py&quot;, line 673, in parse
        p = _parse_sub(source, pattern, 0)
      File &quot;C:\Python27\lib\sre_parse.py&quot;, line 308, in _parse_sub
        itemsappend(_parse(source, state))
      File &quot;C:\Python27\lib\sre_parse.py&quot;, line 401, in _parse
        if state.flags &amp; SRE_FLAG_VERBOSE:
    TypeError: unsupported operand type(s) for &amp;: &#39;tuple&#39; and &#39;int&#39;

Is there a way to use more than one flag ?

Content Type	Original Author	Original Content on Stackoverflow
Question	Smudge	View Question on Stackoverflow
Solution 1 - Python	NPE	View Answer on Stackoverflow
Solution 2 - Python	user647772	View Answer on Stackoverflow
Solution 3 - Python	Wiktor Stribiżew	View Answer on Stackoverflow
Solution 4 - Python	tchrist	View Answer on Stackoverflow

re.sub replace with matched content

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

Solution 4 - Python

Using normal-mode motions in command-line mode in Vim

How to make div occupy remaining height?

Attributions