    remove[c(TRUE, FALSE)]

will do the trick.


----------


*How it works?*

If logical vectors are used for indexing in R, their values are recycled if the index vector is shorter than the vector containing the values.

Here, the vector `remove` contains ten values. If the index vector `c(TRUE, FALSE)` is used, the actual command is: `remove[c(TRUE, FALSE, TRUE, FALSE, TRUE, FALSE, TRUE, FALSE, TRUE, FALSE)]`

Hence, all values with odd index numbers are selected.

Just another alternative:

```r
remove[seq_along(remove) %% 2 &gt; 0]
# [1] 17 19 24 30 44
```

I would like to display a &#39;refresh&#39; symbol in an HTML/JavaScript app I&#39;m creating, but I do not want to make any HTTP requests to load an image. How can I do this reliably across all major browsers?

The closest Unicode value I could find is: &amp;#8634; (`&amp;#8634;`), but the arrow is pointing the wrong way.

Is there another Unicode value that works?

Is there a Webdings font that works? (They don&#39;t usually work in Opera and Firefox.)

Is there a way to create an image in JavaScript using a *base64 image source* provided by a String from that JS?

EDIT:

The reason for this is NOT overhead.  The app being created must be self-contained in a single javascript file, without any other dependencies.  It is a development utility that can be added to any project, without the need for a network.

How can I display a &#39;Reload&#39; symbol in HTML without loading an image via HTTP?

I am learning perl and python... at the same time, not my by design but it has to be done.

Question:

In a perl script I use(see below) at the head of my txt.

    #!/usr/bin/env perl

    use strict;
    use warnings;

Is there something I should be doing on routine for my python scripts?


Does python have a &quot;use strict;&quot; and &quot;use warnings;&quot; like in perl?

Let&#39;s say I had a vector:

`remove &lt;- c(17, 18, 19, 20, 24, 25, 30, 31, 44, 45)`.

How do I select / extract every second value in the vector? Like so: `17, 19, 24, 30, 44`

I&#39;m trying to use the `seq` function: `seq(remove, 2)` but it doesn&#39;t quite work.

Any help is greatly appreciated.

Select every other element from a vector

Let's say I had a vector:
<code>remove &#x3C;- c(17, 18, 19, 20, 24, 25, 30, 31, 44, 45)</code>.
How do I select / extract every second value in the vector? Like so: <code>17, 19, 24, 30, 44</code>
I'm trying to use the <code>seq</code> function: <code>seq(remove, 2)</code> but it doesn't quite work.
Any help is greatly appreciated.

In the documentation, R suggests that raw data files (not Rdata nor Rda) should be placed in `inst/extdata/`

From the first paragraph in: http://cran.r-project.org/doc/manuals/R-exts.html#Data-in-packages

&gt; The data subdirectory is for data files, either to be made available
&gt; via lazy-loading or for loading using data(). (The choice is made by
&gt; the ‘LazyData’ field in the DESCRIPTION file: the default is not to do
&gt; so.) It should not be used for other data files needed by the package,
&gt; and the convention has grown up to use directory inst/extdata for such
&gt; files.

So, I have moved all of my raw data into this folder, but when I build and reload the package and then try to access the data in a function with (for example): 

    read.csv(file=paste(path.package(&quot;my_package&quot;),&quot;/inst/extdata/my_raw_data.csv&quot;,sep=&quot;&quot;)) 
    # .path.package is now path.package in R 3.0+

I get the &quot;cannot open file&quot; error. 

However, it does look like there is a folder called `/extdata` in the package directory with the files in it (post-build and install). What&#39;s happening to the `/inst` folder? 

Does everything in the /inst folder get pushed into the `/` of the package? 

inst and extdata folders in R Packaging

Somewhere after R 2.1.0, I started noticing short phrases next to the R release number that is displayed on start up.  This turns out to be a release nickname, an undocumented component added to the R.Version variable, accessible with `R.Version$nickname`.  

The archives of R-announce show Peter Dalgaard announcing a new release&#39;s nickname on several occasions (e.g., [here][1]) but I don&#39;t find any other information. Despite being a list element of the object queried by `R.Version()`, it is not included in  help file for that function.

Is there any documentation on this feature? Ideally I&#39;d like a statement of the system used to determine a release&#39;s nickname, but any authoritative reference would be great. 


  [1]: http://tolstoy.newcastle.edu.au/R/announce/12/0228.html

Is there any authoritative documentation on R release nicknames?

I have a data frame that has columns a, b, and c. I&#39;d like to add a new column d between b and c.

I know I could just add d at the end by using *cbind* but how can I **insert** it in between two columns? 



Add (insert) a column between two columns in a data.frame

I have created an RMarkdown file in RStudio and managed to knit it with knitr into an HTML and .md file.  Next, I used pandoc to convert the .md file into a PDF file (I get an error if I try and convert from the .html file).  However, the PDF that is produced have massive margins (like this [http://johnmacfarlane.net/pandoc/demo/example13.pdf][1]).  How can I get pandoc to produce something with smaller margins?  I have looked through the pandoc user guide, but haven&#39;t found anything useful.


  [1]: http://johnmacfarlane.net/pandoc/demo/example13.pdf

Set margin size when converting from Markdown to PDF with pandoc

How do I call functions defined in abc.R file in another file, say xyz.R?

A supplementary question is, how do I call functions defined in abc.R from the R prompt/command line?



Define all functions in one .R file, call them from another .R file. How, if possible?

&gt; **Possible Duplicate:**  
&gt; [Why would I prefer using vector to deque](https://stackoverflow.com/questions/5345152/why-would-i-prefer-using-vector-to-deque)  

&lt;!-- End of automatically inserted text --&gt;

I am curious why is it that [`std::vector`](http://en.cppreference.com/w/cpp/container/vector) is so much more popular than [`std::deque`](http://en.cppreference.com/w/cpp/container/deque). Deque is almost as efficient in lookup, more efficient in insert (without vector::reserve)and allows for inserting/deleting in the front. 

Herb Sutter once recommended that [if you want to use vector, just prefer deque](http://www.gotw.ca/gotw/054.htm) (I am paraphrasing). However in a recent talk on [Writing Modern C++](http://channel9.msdn.com/Events/Build/BUILD2011/TOOL-835T) he again strongly recommends thinking of `std::vector` as a default container. According to the [GOTW](http://www.gotw.ca/gotw/054.htm) I linked earlier, even the standard has similar wording. 

Is there a reason for this disparity? Is it just that `vector` is simpler and more well known, or is there a technical reason? Or is it that `vector` is just a cooler name .. ?

Why is std::vector so much more popular than std::deque?

I would like to randomly reorganize the order of the numbers in a vector, in a simple one-line command?

My particular vector V has 150 entries for each value from 1 to 10:

    V &lt;- rep(1:10, each=150)

How to randomize a vector

Suppose I have a std::vector of structs. What happens to the memory if the vector is clear()&#39;d?

    std::vector&lt;myStruct&gt; vecs;
    vecs.resize(10000);
    vecs.clear();

Will the memory be freed, or still attached to the vecs variable as a reusable buffer?


 


Is std::vector memory freed upon a clear?

Im working with the programming language R now.
I have a vector:

    a &lt;- c(&quot;aa&quot;, &quot;bb&quot;, &quot;cc&quot;)
And I want to paste these to a system command, I&#39;m trying it this way now:

    args &lt;- paste(a, sep=&quot; &quot;)
    system(paste(&quot;command&quot;,args, sep=&quot; &quot;))

But now I&#39;m only getting the arguments aa, and I want the arguments aa, bb and cc...

Anyone knows what I&#39;m doing wrong?

Convert R vector to string vector of 1 element

I have a vector **vec** of structures. Such a structure has elements `int a, int b, int c`. I would like to assign to some `int var` the element c, from the last structure in a vector. Please can you provide me with this simple solution? I&#39;m going circle in line like this:

    var = vec.end().c;



How can I get a field from the last element of a vector in C++?

What are good examples of when `seq_along` will work, but `seq` will produce unintended results?

From the documentation of `?seq` we have:

  &gt; Note that it dispatches on the class of the first argument
  &gt; irrespective of argument names. This can have unintended consequences
  &gt; if it is called with just one argument intending this to be taken as
  &gt; `along.with`: it is much better to use `seq_along` in that case.




What are examples of when seq_along works, but seq produces unintended results?

What is the difference between size and length of a Seq? When to use one and when the other?

    scala&gt; var a :Seq[String] = Seq(&quot;one&quot;, &quot;two&quot;)
    a: Seq[String] = List(one, two)

    scala&gt; a.size
    res6: Int = 2

    scala&gt; a.length
    res7: Int = 2

It&#39;s the same?

Thanks

Content Type	Original Author	Original Content on Stackoverflow
Question	user1313954	View Question on Stackoverflow
Solution 1 - R	Sven Hohenstein	View Answer on Stackoverflow
Solution 2 - R	Grega Kešpret	View Answer on Stackoverflow
Solution 3 - R	Jilber Urbina	View Answer on Stackoverflow

Select every other element from a vector

R Problem Overview

R Solutions

Solution 1 - R

Solution 2 - R

Solution 3 - R

Does python have a "use strict;" and "use warnings;" like in perl?

How can I display a 'Reload' symbol in HTML without loading an image via HTTP?

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