So I can start from `collection[len(collection)-1]` and end in `collection[0]`.

I also want to be able to access the loop index.

Traverse a list in reverse order in Python

Given a dictionary like so:

    my_map = {&#39;a&#39;: 1, &#39;b&#39;: 2}

How can one invert this map to get:

    inv_map = {1: &#39;a&#39;, 2: &#39;b&#39;}


Reverse / invert a dictionary mapping

How do you reverse a string in-place in JavaScript when it is passed to a function with a return statement, without using built-in functions (`.reverse()`, `.charAt()` etc.)?

How do you reverse a string in-place in JavaScript?

How can you produce the following list with `range()` in Python?

    [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]


Print a list in reverse order with range()?

I&#39;m using JQuery to select some elements on a page and then move them around in the DOM. The problem I&#39;m having is I need to select all the elements in the reverse order that JQuery naturally wants to select them. For example:

    &lt;ul&gt;
       &lt;li&gt;Item 1&lt;/li&gt;
       &lt;li&gt;Item 2&lt;/li&gt;
       &lt;li&gt;Item 3&lt;/li&gt;
       &lt;li&gt;Item 4&lt;/li&gt;
       &lt;li&gt;Item 5&lt;/li&gt;
    &lt;/ul&gt;

I want to select all the li items and use the .each() command on them but I want to start with Item 5, then Item 4 etc. Is this possible?

JQuery .each() backwards

How can I sort this list in descending order?

    timestamps = [
        &quot;2010-04-20 10:07:30&quot;,
        &quot;2010-04-20 10:07:38&quot;,
        &quot;2010-04-20 10:07:52&quot;,
        &quot;2010-04-20 10:08:22&quot;,
        &quot;2010-04-20 10:08:22&quot;,
        &quot;2010-04-20 10:09:46&quot;,
        &quot;2010-04-20 10:10:37&quot;,
        &quot;2010-04-20 10:10:58&quot;,
        &quot;2010-04-20 10:11:50&quot;,
        &quot;2010-04-20 10:12:13&quot;,
        &quot;2010-04-20 10:12:13&quot;,
        &quot;2010-04-20 10:25:38&quot;
    ]


Python list sort in descending order

I want to have a reversed list view on a list (in a similar way than `List#sublist` provides a sublist view on a list). Is there some function which provides this functionality?

I don&#39;t want to make any sort of copy of the list nor modify the list.

It would be enough if I could get at least a reverse iterator on a list in this case though.

---

Also, I know how to implement this myself. I&#39;m just asking if Java already provides something like this.

Demo implementation:

    static &lt;T&gt; Iterable&lt;T&gt; iterableReverseList(final List&lt;T&gt; l) {
    	return new Iterable&lt;T&gt;() {
    		public Iterator&lt;T&gt; iterator() {
    			return new Iterator&lt;T&gt;() {
    				ListIterator&lt;T&gt; listIter = l.listIterator(l.size());    				
					public boolean hasNext() { return listIter.hasPrevious(); }
					public T next() { return listIter.previous(); }
					public void remove() { listIter.remove(); }    				
				};
    		}
		};
    }

---

I just have found out that some `List` implementations have `descendingIterator()` which is what I need. Though there is no general such implementation for `List`. Which is kind of strange because the implementation I have seen in `LinkedList` is general enough to work with any `List`.

How to get a reversed list view on a list in Java?

How can i get a reversed array in angular?
i&#39;m trying to use orderBy filter, but it needs a predicate(e.g. &#39;name&#39;) to sort:

    &lt;tr ng-repeat=&quot;friend in friends | orderBy:&#39;name&#39;:true&quot;&gt;
          &lt;td&gt;{{friend.name}}&lt;/td&gt;
          &lt;td&gt;{{friend.phone}}&lt;/td&gt;
          &lt;td&gt;{{friend.age}}&lt;/td&gt;
    &lt;tr&gt;

Is there a way to reverse original array, without sorting.
like that:

    &lt;tr ng-repeat=&quot;friend in friends | orderBy:&#39;&#39;:true&quot;&gt;
          &lt;td&gt;{{friend.name}}&lt;/td&gt;
          &lt;td&gt;{{friend.phone}}&lt;/td&gt;
          &lt;td&gt;{{friend.age}}&lt;/td&gt;
    &lt;tr&gt;


angular ng-repeat in reverse

Here is my code:

    import pandas as pd

    data = pd.DataFrame({&#39;Odd&#39;:[1,3,5,6,7,9], &#39;Even&#39;:[0,2,4,6,8,10]})

    for i in reversed(data):
        print(data[&#39;Odd&#39;], data[&#39;Even&#39;])

When I run this code, i get the following error:

    Traceback (most recent call last):
      File &quot;C:\Python33\lib\site-packages\pandas\core\generic.py&quot;, line 665, in _get_item_cache
        return cache[item]
    KeyError: 5
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File &quot;C:\Users\*****\Documents\******\********\****.py&quot;, line 5, in &lt;module&gt;
        for i in reversed(data):
      File &quot;C:\Python33\lib\site-packages\pandas\core\frame.py&quot;, line 2003, in __getitem__
        return self._get_item_cache(key)
      File &quot;C:\Python33\lib\site-packages\pandas\core\generic.py&quot;, line 667, in _get_item_cache
        values = self._data.get(item)
      File &quot;C:\Python33\lib\site-packages\pandas\core\internals.py&quot;, line 1656, in get
        _, block = self._find_block(item)
      File &quot;C:\Python33\lib\site-packages\pandas\core\internals.py&quot;, line 1936, in _find_block
        self._check_have(item)
      File &quot;C:\Python33\lib\site-packages\pandas\core\internals.py&quot;, line 1943, in _check_have
        raise KeyError(&#39;no item named %s&#39; % com.pprint_thing(item))
    KeyError: &#39;no item named 5&#39;

**Why am I getting this error?  
How can I fix that?   
What is the right way to reverse &lt;code&gt;pandas.DataFrame&lt;/code&gt;?**

Right way to reverse a pandas DataFrame?

How do you reverse a string in C or C++ without requiring a separate buffer to hold the reversed string?


How do you reverse a string in place in C or C++?

I need to run through a List in reverse order using Java. 

So where this does it forwards:

    for(String string: stringList){
    //...do something
    }

Is there some way to iterate the stringList in reverse order using the *for each* syntax?

For clarity: I know how to iterate a list in reverse order but would like to know (for curiosity&#39;s sake ) how to do it in the *for each* style.

Can one do a for each loop in java in reverse order?

How to read a file in reverse order using python? I want to read a file from last line to first line.


How to read a file in reverse order?

I receive a dictionary as input, and would like to to return a dictionary whose keys will be the input&#39;s values and whose value will be the corresponding input keys. Values are unique.

For example, say my input is:

    a = dict()
    a[&#39;one&#39;]=1
    a[&#39;two&#39;]=2

I would like my output to be:

    {1: &#39;one&#39;, 2: &#39;two&#39;}

To clarify I would like my result to be the equivalent of the following:

    res = dict()
    res[1] = &#39;one&#39;
    res[2] = &#39;two&#39;

Any neat Pythonic way to achieve this?


How do I exchange keys with values in a dictionary?

How can we reverse a simple string in Go?

How to reverse a string in Go?

In Python, what is the best way to create a new list whose items are the same as those of some other list, but in reverse order? (I don&#39;t want to modify the existing list in place.)

Here is one solution that has occurred to me:

    new_list = list(reversed(old_list))

It&#39;s also possible to duplicate `old_list` then reverse the duplicate in place:

    new_list = list(old_list) # or `new_list = old_list[:]`
    new_list.reverse()

Is there a better option that I&#39;ve overlooked? If not, is there a compelling reason (such as efficiency) to use one of the above approaches over the other?

Best way to create a &quot;reversed&quot; list in Python?

I have the following code:

```cs
public class CategoryNavItem
{
    public int ID { get; set; }
    public string Name { get; set; }
    public string Icon { get; set; }

    public CategoryNavItem(int CatID, string CatName, string CatIcon)
    {
        ID = CatID;
        Name = CatName;
        Icon = CatIcon;
    }
}

public static List&lt;Lite.CategoryNavItem&gt; getMenuNav(int CatID)
{
    List&lt;Lite.CategoryNavItem&gt; NavItems = new List&lt;Lite.CategoryNavItem&gt;();

    -- Snipped code --

    return NavItems.Reverse();
}
```

But I get the following error:

&gt; Cannot implicitly convert type &#39;void&#39; to `&#39;System.Collections.Generic.List&lt;Lite.CategoryNavItem&gt;&#39;`

Any ideas why this might be?

c# Trying to reverse a list

I am using django 1.2 and going from one view to another using the urlresolvers reverse method.

    url = reverse(viewOne)

and I want to pass a get parameter, for example 

&gt; name = &#39;joe&#39;

so that in the viewOne if I do 

    def viewOne(request):
        request.GET[&#39;name&#39;]
I will get

    joe

how do I do that ? 

How do i pass GET parameters using django urlresolvers reverse

Suppose I have a vector `v`, how do I get its reverse, i.e. last element first?

The first thing that comes to me is `v[length(v):1]`, but it returns NA when `v` is `numeric(0)`, while user normally expect sorting nothing returns nothing, not sorting nothing returns the unavailable thing - it does make a big difference in my case.

How to reverse order a vector?

Is there a way of printing arrays in C++?

I&#39;m trying to make a function that reverses a user-input array and then prints it out. I tried Googling this problem and it seemed like C++ can&#39;t print arrays. That can&#39;t be true can it?

Printing an array in C++?

I&#39;m trying to reverse a named URL and include a querystring in it. Basically, I&#39;ve modified the login function, and I want to send `?next=` in it.

Here&#39;s what I&#39;m doing now: `reverse(name) + &quot;?next=&quot; + reverse(redirect)`

Here&#39;s what I&#39;d like to do: `reverse(name, kwargs = { &#39;next&#39;:reverse(redirect) } )`

My URL for the login page (just as an example) looks like this:

`url(r&#39;^login/&#39;, custom_login, name = &#39;login&#39;),`

So how do I modify this whole thing (or call it) to include the next without having to concatenate it? It feels like an iffy solution at best.

Including a querystring in a django.core.urlresolvers reverse() call

Consider the following command line snippet: 

    $ cd /tmp/
    $ mkdir dirA
    $ mkdir dirB
    $ echo &quot;the contents of the &#39;original&#39; file&quot; &gt; orig.file
    $ ls -la orig.file 
    -rw-r--r-- 1 $USER $USER 36 2010-12-26 00:57 orig.file
    
    # create symlinks in dirA and dirB that point to /tmp/orig.file:
    
    $ ln -s $(pwd)/orig.file $(pwd)/dirA/
    $ ln -s $(pwd)/orig.file $(pwd)/dirB/lorig.file
    $ ls -la dirA/ dirB/
    dirA/:
    total 44
    drwxr-xr-x  2 $USER $USER  4096 2010-12-26 00:57 .
    drwxrwxrwt 20 root          root          36864 2010-12-26 00:57 ..
    lrwxrwxrwx  1 $USER $USER    14 2010-12-26 00:57 orig.file -&gt; /tmp/orig.file
    
    dirB/:
    total 44
    drwxr-xr-x  2 $USER $USER  4096 2010-12-26 00:58 .
    drwxrwxrwt 20 root          root          36864 2010-12-26 00:57 ..
    lrwxrwxrwx  1 $USER $USER    14 2010-12-26 00:58 lorig.file -&gt; /tmp/orig.file

At this point, I can use `readlink` to see what is the &#39;original&#39; (well, I guess the usual term here is either &#39;target&#39; or &#39;source&#39;, but those in my mind can be opposite concepts as well, so I&#39;ll just call it &#39;original&#39;) file of the symlinks, i.e.

    $ readlink -f dirA/orig.file 
    /tmp/orig.file
    $ readlink -f dirB/lorig.file 
    /tmp/orig.file

... However, what I&#39;d like to know is - is there a command I could run on the &#39;original&#39; file, and find all the symlinks that point to it? In other words, something like (pseudo):

    $ getsymlinks /tmp/orig.file
    /tmp/dirA/orig.file 
    /tmp/dirB/lorig.file

Thanks in advance for any comments, 

Cheers!

Linux: Find all symlinks of a given &#39;original&#39; file? (reverse &#39;readlink&#39;)

String.fromCharCode(72) gives H. How to get number 72 from char H?

How to reverse String.fromCharCode?

What is the best way to loop over a python string backwards?

The following seems a little awkward for all the need of -1 offset:

    string = &quot;trick or treat&quot;
    for i in range(len(string)-1, 0-1, -1):
        print string[i]

The following seems more succinct, but is it actually generate a reversed string so that there is a minor performance penalty?

    string = &quot;trick or treat&quot;
    for c in string[::-1]:
        print c





Best way to loop over a python string backwards

Ok so I have been looking around at just about every option under the sun for capturing multi-touch gestures, and I have finally come full circle and am back at the UIPanGestureRecognizer.

The functionality I want is really quite simple. I have setup a two finger pan gesture, and I want to be able to shuffle through some images depending on how many pixels I move. I have all that worked out okay, but I want to be able to capture if the pan gesture is REVERSED.

Is there a built in way that I&#39;m just not seeing to detect going back on a gesture? Would I have to store my original starting point, then track the end point, then see where they move after that and se if its less than the initial ending point and then reverse accordingly? I can see that working, but I&#39;m hoping there is a more elegant solution!!


Thanks

EDIT:

Here is the method that the recognizer is set to fire. Its a bit of a hack, but it works:

    -(void) throttle:(UIGestureRecognizer *) recognize{
	
	throttleCounter ++;
	
	if(throttleCounter == 6){
		throttleCounter = 0;
		[self nextPic:nil];
	}
	
	UIPanGestureRecognizer *panGesture = (UIPanGestureRecognizer *) recognize;
	UIView *view = recognize.view;
	if(panGesture.state == UIGestureRecognizerStateBegan){
		CGPoint translation = [panGesture translationInView:view.superview];
		NSLog(@&quot;X: %f, Y:%f&quot;, translation.x, translation.y);
	}else if(panGesture.state == UIGestureRecognizerStateEnded){
		CGPoint translation = [panGesture translationInView:view.superview];
				NSLog(@&quot;X: %f, Y:%f&quot;, translation.x, translation.y);
	}
      }

I&#39;ve just gotten to the point where I am going to start trying to track the differences between values...to try and tell which way they are panning



How can I capture which direction is being panned using UIPanGestureRecognizer?

I have an array of objects.

Is it possible to make a new array that is a copy of this array, but in reverse order?
I was looking for something like this. 

    // my array
    ArrayList&lt;Element&gt; mElements = new ArrayList&lt;Element&gt;();
    // new array
    ArrayList&lt;Element&gt; tempElements = mElements;
    
    tempElements.reverse(); // something to reverse the order of the array



android - reverse the order of an array

Trying to configure my reverse proxy with basic authentication before forward the traffic to my back end server. Can any one give me a solution.

Example here:

User(internet) -&gt; reverse proxy / vhosts server (need to add basic authentication here ) -&gt; back end server ( non authenticated )

Apache reverse proxy with basic authentication

Im trying to figure out how to reverse the string `temp` when I have the string read in binary numbers 

    istream&amp; operator &gt;&gt;(istream&amp; dat1d, binary&amp; b1)    
    {              
        string temp; 
        
        dat1d &gt;&gt; temp;    
    }

How to reverse an std::string?

I have an android apk and I deleted my source code and dont have the project again, I want to change the version code of the old apk. my question is how do I unzip and repack the apk so I can use the. am using a mac system. I saw so many things for windows but i couldnt find for mac.I need help please

How to unzip, edit and zip an android apk

Is there any way I can iterate backwards (in reverse) through a SortedDictionary in c#?

Or is there a way to define the SortedDictionary in descending order to begin with? 

Reverse Sorted Dictionary in .NET

This is my code :

    a = {0:&#39;000000&#39;,1:&#39;11111&#39;,3:&#39;333333&#39;,4:&#39;444444&#39;}
    
    for i in a:
        print i


it shows:

    0
    1
    3
    4

but I want it to show:

    4
    3
    1
    0


so, what can I do?


How to reverse order of keys in python dict?

If I have an array like this:

    1 4 9 16 9 7 4 9 11 

What is the best way to reverse the array so that it looks like this:

    11 9 4 7 9 16 9 4 1 

I have the code below, but I feel it is a little tedious:

    public int[] reverse3(int[] nums) {
        return new int[] { nums[8], nums[7], nums[6], nums[5], num[4],
                           nums[3], nums[2], nums[1], nums[0] };
    }

Is there a simpler way?


All Reverse Solutions on Gang of Coders

Total of 31 Reverse Solutions