`.Last.value` is an answer.

[It was answered once](https://stackoverflow.com/questions/3082716/equivalent-of-matlab-ans-in-r) but you have better title.

I have data with latitude and longitude stored in my SQLite database, and I want to get the nearest locations to the parameters I put in (ex. My current location - lat/lng, etc.).

I know that this is possible in MySQL, and I&#39;ve done quite some research that SQLite needs a custom external function for the Haversine formula (calculating distance on a sphere), but I haven&#39;t found anything that is written in Java and works.

Also, if I want to add custom functions, I need the `org.sqlite` .jar (for `org.sqlite.Function`), and that adds unnecessary size to the app.

The other side of this is, I need the Order by function from SQL, because displaying the distance alone isn&#39;t that much of a problem - I already did it in my custom SimpleCursorAdapter, but I can&#39;t sort the data, because I don&#39;t have the distance column in my database. That would mean updating the database every time the location changes and that&#39;s a waste of battery and performance. So if someone has any idea on sorting the cursor with a column that&#39;s not in the database, I&#39;d be grateful too!

I know there are tons of Android apps out there that use this function, but can someone please explain the magic.

By the way, I found this alternative: https://stackoverflow.com/questions/3126830

It&#39;s suggesting to make 4 new columns for cos and sin values of lat and lng, but is there any other, not so redundant way?

SQlite Getting nearest locations (with latitude and longitude)

I get an error message when I use this expression:

    re.sub(r&quot;([^\s\w])(\s*\1)+&quot;,&quot;\\1&quot;,&quot;...&quot;)

I checked the regex at [RegExr][1] and it returns `.` as expected.  But when I try it in Python I get this error message:

    raise error, v # invalid expression
    sre_constants.error: nothing to repeat

Can someone please explain?


  [1]: http://regexr.com/3ctdn

regex error - nothing to repeat

Suppose I&#39;m using R&#39;s interactive console, and I&#39;ve just done something like this:

    long_running_command()

That long-running command returns a value, and I&#39;ve just realized that I wanted to assign that value to a variable instead of discard it. So how can I get that value without running the command again? Is there a command like this?

    result = get_last_return_value()



How to assign the result of the previous expression to a variable?

Suppose I'm using R's interactive console, and I've just done something like this:
<pre><code class="hljs language-scss">long_running_command()
</code></pre>
That long-running command returns a value, and I've just realized that I wanted to assign that value to a variable instead of discard it. So how can I get that value without running the command again? Is there a command like this?
<pre><code class="hljs language-ini">result = get_last_return_value()
</code></pre>

I&#39;m plotting a categorical variable and instead of showing the counts for each category value.

I&#39;m looking for a way to get `ggplot` to display the percentage of values in that category. Of course, it is possible to create another variable with the calculated percentage and plot that one, but I have to do it several dozens of times and I hope to achieve that in one command.

I was experimenting with something like 

    qplot(mydataf) +
      stat_bin(aes(n = nrow(mydataf), y = ..count../n)) +
      scale_y_continuous(formatter = &quot;percent&quot;)

but I must be using it incorrectly, as I got errors.

To easily reproduce the setup, here&#39;s a simplified example:

    mydata &lt;- c (&quot;aa&quot;, &quot;bb&quot;, NULL, &quot;bb&quot;, &quot;cc&quot;, &quot;aa&quot;, &quot;aa&quot;, &quot;aa&quot;, &quot;ee&quot;, NULL, &quot;cc&quot;);
    mydataf &lt;- factor(mydata);
    qplot (mydataf); #this shows the count, I&#39;m looking to see % displayed.

In the real case, I&#39;ll probably use `ggplot` instead of `qplot`, but the right way to use [stat_bin][1] still eludes me.

I&#39;ve also tried these four approaches:

    ggplot(mydataf, aes(y = (..count..)/sum(..count..))) + 
      scale_y_continuous(formatter = &#39;percent&#39;);

    ggplot(mydataf, aes(y = (..count..)/sum(..count..))) + 
      scale_y_continuous(formatter = &#39;percent&#39;) + geom_bar();

    ggplot(mydataf, aes(x = levels(mydataf), y = (..count..)/sum(..count..))) + 
      scale_y_continuous(formatter = &#39;percent&#39;);
    
    ggplot(mydataf, aes(x = levels(mydataf), y = (..count..)/sum(..count..))) + 
      scale_y_continuous(formatter = &#39;percent&#39;) + geom_bar();

but all 4 give:

&gt;     Error: ggplot2 doesn&#39;t know how to deal with data of class factor

The same error appears for the simple case of 

    ggplot (data=mydataf, aes(levels(mydataf))) +
      geom_bar()

so it&#39;s clearly something about how `ggplot` interacts with a single vector. I&#39;m scratching my head, googling for that error gives a single [result][2]. 


  [1]: http://had.co.nz/ggplot2/stat_bin.html
  [2]: http://groups.google.com/group/ggplot2/browse_thread/thread/0489a702f3afc83b

Show percent % instead of counts in charts of categorical variables

Can anyone tell me how to find the common elements from multiple vectors?

    a &lt;- c(1,3,5,7,9)
    b &lt;- c(3,6,8,9,10)
    c &lt;- c(2,3,4,5,7,9)

I want to get the common elements from the above vectors (ex: 3 and 9) 

How to find common elements from multiple vectors?

    cbind(1:2, 1:10)  
         [,1] [,2]  
      [1,]    1    1  
      [2,]    2    2  
      [3,]    1    3  
      [4,]    2    4  
      [5,]    1    5  
      [6,]    2    6  
      [7,]    1    7  
      [8,]    2    8  
      [9,]    1    9  
     [10,]    2   10  

I want an output like below  

    [,1] [,2]  
    [1,] 1 1  
    [2,] 2 2  
    [3,]   3  
    [4,]   4  
    [5,]   5  
    [6,]   6  
    [7,]   7  
    [8,]   8  
    [9,]   9  
    [10,]  10  



How to cbind or rbind different lengths vectors without repeating the elements of the shorter vectors?

Is it possible to plot a matrix of scatter plots with `ggplot2`, using `ggplot`&#39;s nice features like mapping additional factors to color, shape etc. and adding smoother?

I am thinking about something similar to the `base` function `pairs`.

Create a matrix of scatterplots (pairs() equivalent) in ggplot2

I have a data.frame, that is sorted from highest to lowest. For example: 

    x &lt;- structure(list(variable = structure(c(10L, 6L, 3L, 4L, 2L, 8L, 
    9L, 5L, 1L, 7L), .Label = c(&quot;a&quot;, &quot;b&quot;, &quot;c&quot;, &quot;d&quot;, &quot;e&quot;, &quot;f&quot;, &quot;g&quot;, 
    &quot;h&quot;, &quot;i&quot;, &quot;j&quot;), class = c(&quot;ordered&quot;, &quot;factor&quot;)), value = c(0.990683229813665, 
    0.975155279503106, 0.928571428571429, 0.807453416149068, 0.717391304347826, 
    0.388198757763975, 0.357142857142857, 0.201863354037267, 0.173913043478261, 
    0.0496894409937888)), .Names = c(&quot;variable&quot;, &quot;value&quot;), row.names = c(10L, 
    6L, 3L, 4L, 2L, 8L, 9L, 5L, 1L, 7L), class = &quot;data.frame&quot;)

    ggplot(x, aes(x=variable,y=value)) + geom_bar(stat=&quot;identity&quot;) + 
     scale_y_continuous(&quot;&quot;,label=scales::percent) + coord_flip() 

Now, the data is nice and sorted, but when I plot, it comes out sorted by factor. It&#39;s annoying, how do I fix it?

ggplot2: sorting a plot

I&#39;m refactoring a large javascript document that I picked up from an open source project.  A number of functions use inconsistent return statements.  Here&#39;s a simple example of what I mean:

    var func = function(param) {
        if (!param) {
            return;
        }
        // do stuff
        return true;
    }

Sometimes the functions return boolean, sometimes strings or other things.  Usually they are inconsistently paired with a simple `return;` statement inside of a conditional.

The problem is that the code is complex.  It is a parser that uses a multitude of unique RegEx matches, creates and destroys DOM nodes on the fly, etc.  Preliminary testing shows that, in the above example, I could change the `return;` statement to become `return false;`, but I&#39;m concerned that I may not realize that it had a negative impact (i.e. some feature stopped working) on the script until much later.

So my questions:  Is there a benefit to using a blank return statement?  Could this have been intentionally coded this way or was it just lazy? Can I change them all to `return false;`, or `return null;` or do I need to dig through every call and find out what they are doing with the results of those functions?

Is there a benefit to using a return statement that returns nothing?

In C++ what is the best way to return a function local std::string variable from the function?

    std::string MyFunc()
    {
        std::string mystring(&quot;test&quot;);
        return mystring;
    
    }
    
    std::string ret = MyFunc(); // ret has no value because mystring has already gone out of scope...???

best way to return an std::string that local to a function

I wonder if it is bad manner to skip `return None`, when it is not needed.

Example:

    def foo1(x):
        if [some condition]:
            return Baz(x)
        else:
            return None

    def foo2(x):
        if [some condition]:
            return Baz(x)

    bar1 = foo1(x)
    bar2 = foo2(x)

In both cases, when condition is false, function will return with `None`.

Is it ok to skip &quot;return None&quot;?

I&#39;m writing 2 functions in matlab, an initialize function and a function to insert items into an array treating it like a doubly-linked list. However, my initialize function only returns &quot;ans =&quot; and the initialized array. How can I have it also set values of my other variables? Here&#39;s my code: 

    function [ array, listp, freep ] = initialize( size )
        array = zeros(size, 3);
        listp = 0;
        freep = 1;
    end

MATLAB - multiple return values from a function?

What is the difference between the `return` and `exit` statement in Bash functions with respect to exit codes?

Difference between return and exit in Bash functions

Normally you can execute a Python script for example: `python myscript.py`, but if you are in the interactive mode, how is it possible to execute a Python script on the filesystem?

    &gt;&gt;&gt; exec(File) ???

It should be possible to execute the script more than one time. 



Is there a possibility to execute a Python script while being in interactive mode

when I write Python code from the interpreter I can type `dir()` to have a list of names defined in the current scope. How can achieve to have the same information, programmatically, when I develop Javascript code from a browser using an interactive console like firebug, chrome console, etc?


Equivalent of Python&#39;s dir in Javascript

I&#39;m looking for an interactive graphing library for Python. 

By &quot;[graph][1]&quot;, I meant a set of nodes connected by a set of vertices (not a plot of values over x-y axis, nor a grid of pixels).

By &quot;interactive&quot;, I meant I can drag-and-drop the nodes around and I need to be able to click on the nodes/vertices and have the library pass the nodes/vertices to my callbacks, which may add/remove nodes/vertices or display information (I cannot load the full graph at startup as the dataset is too large/complex; instead I&#39;ll be loading only the necessary slices of data depending on user inputs).

By Python, I meant the programming language [Python][2], the graphing library should have CPython binding. I have Python 2.7 and Python 3.1, but can downgrade to 2.6 if necessary. This language requirement is because the dataset I&#39;m working with only have Python binding.

The graphing library must support [directed graph](http://en.wikipedia.org/wiki/Directed_graph) and be able to layout the nodes automatically. I need to put labels on the nodes.

Preferably, the layouting algorithm should place adjacent nodes near each other. It should be able to handle from 100-1000 nodes and about 300-4000 vertices reasonably in my 4 year old laptop (I typically start with around 100 nodes, but the number might expand depending on user input). Preferably it should be a library with not too many dependencies (except perhaps for Gnome). Open source is preferred.

I have already written a simple prototype of my program using Tkinter Canvas, but I need a more serious graphing library to expand the program. I&#39;ve looked at graphviz and matplotlib, but apparently they&#39;re only for working with static graphs and apparently would need significant amount of work to do interactive manipulations (correct me if I&#39;m wrong, I&#39;ve only looked at them briefly). I&#39;ve also tried generating the graph to an SVG file and using Inkscape to view it, but it&#39;s too slow and takes too much memory and because of the sheer number of vertices it becomes a tangled mess.


  [1]: http://en.wikipedia.org/wiki/Graph_%28mathematics%29
  [2]: http://en.wikipedia.org/wiki/Python_%28programming_language%29

Is there an interactive graphing library for python

I used **matplotlib** to create some plot, which depends on 8 variables. I would like to study how the plot changes when I change some of them. I created some script that calls the **matplotlib** one and generates different snapshots that later I convert into a movie, it is not bad, but a bit clumsy. 

1. I wonder if somehow I could interact with the plot regeneration using keyboard keys to increase / decrease values of some of the variables and see instantly how the plot changes. 

2. What is the best approach for this? 

3. Also if you can point me to interesting links or a link with a plot example with just two sliders?

Interactive matplotlib plot with two sliders

I&#39;m trying to squash a range of commits - HEAD to HEAD~3.  Is there a quick way to do this, or do I need to use rebase --interactive?

Is there a way to squash a number of commits non-interactively?

It&#39;s frustrating when I do something like `man bindkey` and i get:

&lt;pre&gt;
BUILTIN(1)                BSD General Commands Manual               BUILTIN(1)

NAME
     builtin, !, %, ., :, @, {, }, alias, alloc, bg, bind, bindkey, break, breaksw, builtins, case, cd, chdir, command,
     complete, continue, default, dirs, do, done, echo, echotc, elif, else, end, endif, endsw, esac, eval, exec, exit,
     export, false, fc, fg, filetest, fi, for, foreach, getopts, glob, goto, hash, hashstat, history, hup, if, jobid,
     jobs, kill, limit, local, log, login, logout, ls-F, nice, nohup, notify, onintr, popd, printenv, pushd, pwd, read,
     readonly, rehash, repeat, return, sched, set, setenv, settc, setty, setvar, shift, source, stop, suspend, switch,
     telltc, test, then, time, times, trap, true, type, ulimit, umask, unalias, uncomplete, unhash, unlimit, unset,
     unsetenv, until, wait, where, which, while -- shell built-in commands

SYNOPSIS
     builtin [-options] [args ...]

DESCRIPTION
     Shell builtin commands are commands that can be executed within the running shell&#39;s process.  Note that, in the
&lt;/pre&gt;

Is there an easy way to access the documentation for such commands?


How can I read documentation about built in zsh commands?

I am in a situation where I want to use mutable versions of things like Integer. Do I have to use these classes (below) or does Java have something built in?

http://www.java2s.com/Code/Java/Data-Type/Amutableintwrapper.htm 

Does Java have mutable types for Integer, Float, Double, Long?

Seeing Alexandre C&#39;s [reply][1] in the other topic, I&#39;m curious to know that if there is any performance difference with the built-in types: 

&gt; `char` vs `short` vs `int` vs. `float`
&gt; vs. `double`.

Usually we don&#39;t consider such performance difference (if any) in our real life projects, but I would like to know this for educational purpose. The general questions can be asked is:

- Is there any performance difference between integral arithmetics and floating-point arithmetic?

- Which is faster? What is the reason for being faster? Please explain this.


[1]:https://stackoverflow.com/questions/5069319/predefinition-of-often-used-values-in-computations-does-it-change-anything/5069349#5069349

Performance of built-in types : char vs short vs int vs. float vs. double

I came across a `#define` in which they use `__builtin_expect`.

[The documentation][1] says:

&gt; ### Built-in Function: `long __builtin_expect (long exp, long c)`  
 
&gt; You may use `__builtin_expect` to provide the compiler with branch
&gt; prediction information. In general, you should prefer to use actual
&gt; profile feedback for this (`-fprofile-arcs`), as programmers are
&gt; notoriously bad at predicting how their programs actually perform.
&gt; However, there are applications in which this data is hard to collect.
&gt; 
&gt; 
&gt; The return value is the value of `exp`, which should be an integral
&gt; expression. The semantics of the built-in are that it is expected that
&gt; `exp == c`. For example: 
&gt; 
&gt;           if (__builtin_expect (x, 0))
&gt;             foo ();
&gt;
&gt;  would indicate that we do not expect to call `foo`, since we expect `x` to be zero.

So why not directly use: 
    
    if (x)
        foo ();

instead of the complicated syntax with `__builtin_expect`?

  [1]: https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-g_t_005f_005fbuiltin_005fexpect-4159


What is the advantage of GCC&#39;s __builtin_expect in if else statements?

When I try to use the `read` command in Bash like this:

    echo hello | read str
    echo $str

Nothing echoed, while I think `str` should contain the string `hello`. Can anybody please help me understand this behavior?

Content Type	Original Author	Original Content on Stackoverflow
Question	Ryan C. Thompson	View Question on Stackoverflow
Solution 1 - R	Marek	View Answer on Stackoverflow

How to assign the result of the previous expression to a variable?

R Problem Overview

R Solutions

Solution 1 - R

regex error - nothing to repeat

SQlite Getting nearest locations (with latitude and longitude)

Attributions