There are several solutions to this.

One of them is to use `sprintf`. This uses `C` style formatting codes embedded in a character string to indicate the format of any other arguments passed to it.  For example, the formatting code `%3d` means format a number as integer of width 3:

    a &lt;- seq(1,101,25)
    sprintf(&quot;name_%03d&quot;, a)
    [1] &quot;name_001&quot; &quot;name_026&quot; &quot;name_051&quot; &quot;name_076&quot; &quot;name_101&quot;

Another is `formatC` and `paste`:

    paste(&quot;name&quot;, formatC(a, width=3, flag=&quot;0&quot;), sep=&quot;_&quot;)
    [1] &quot;name_001&quot; &quot;name_026&quot; &quot;name_051&quot; &quot;name_076&quot; &quot;name_101&quot;




While solving a geometry problem, I came across an approach called Sliding Window Algorithm.

Couldn&#39;t really find any study material/details on it.

What is the algorithm about?

What is Sliding Window Algorithm? Examples?

First of all, I know that using regex for email is not recommended but I gotta test this out.

I have this regex:

    \b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

In Java, I did this:

    Pattern p = Pattern.compile(&quot;\\b[A-Z0-9._%-]+@[A-Z0-9.-]+\\.[A-Z]{2,4}\\b&quot;);
    Matcher m = p.matcher(&quot;foobar@gmail.com&quot;);
		
    if (m.find())
        System.out.println(&quot;Correct!&quot;);

However, the regex fails regardless of whether the email is wel-formed or not. A &quot;find and replace&quot; inside Eclipse works fine with the same regex.

Any idea?

Thanks,


Java regex email

The following code

    a &lt;- seq(1,101,25)
    b &lt;- paste(&quot;name&quot;, 1:length(a), sep = &quot;_&quot;)

produces this output:

    &quot;name_1&quot;  &quot;name_26&quot;  &quot;name_51&quot;  &quot;name_76&quot;  &quot;name_101&quot;

I&#39;d like to have the same width of all values which means for me to fill the values with zeros like this:

    &quot;name_001&quot;  &quot;name_026&quot;  &quot;name_051&quot;  &quot;name_076&quot;  &quot;name_101&quot;

How do I handle that?

&lt;sub&gt;(This question is related to [this one][1].)&lt;/sub&gt;

  [1]: https://stackoverflow.com/questions/8260808/transpose-reshape-rows-in-coloums-with-given-conditions



Format number as fixed width, with leading zeros

The following code
<pre><code class="hljs language-perl">a &#x3C;- seq(1,101,25)
b &#x3C;- paste("name", 1:length(a), sep = "_")
</code></pre>
produces this output:
<pre><code class="hljs language-arduino">"name_1" "name_26" "name_51" "name_76" "name_101"
</code></pre>
I'd like to have the same width of all values which means for me to fill the values with zeros like this:
<pre><code class="hljs language-arduino">"name_001" "name_026" "name_051" "name_076" "name_101"
</code></pre>
How do I handle that?
(This question is related to <a href="https://stackoverflow.com/questions/8260808/transpose-reshape-rows-in-coloums-with-given-conditions" target="_blank" rel="noopener noreferrer">this one</a>.)

I am struggling to find the appropriate function that would return a specified number of rows picked up randomly without replacement from a data frame in R language? Can anyone help me out?

Sample random rows in dataframe

I have loaded in a R console different type of objects.
I can remove them all using

    rm(list=ls())

or remove only the functions (but not the variables) using

    rm(list=lsf.str())

My question is:
is there a way to remove all variables except the functions

remove all variables except functions

Here&#39;s a little piece of code I wrote to report variables with missing values from a data frame.  I&#39;m trying to think of a more elegant way to do this, one that perhaps returns a data.frame, but I&#39;m stuck:

    for (Var in names(airquality)) {
    	missing &lt;- sum(is.na(airquality[,Var]))
    	if (missing &gt; 0) {
    		print(c(Var,missing))
    	}
    }

Edit: I&#39;m dealing with data.frames with dozens to hundreds of variables, so it&#39;s key that we only report variables with missing values.

Elegant way to report missing values in a data.frame

I&#39;m an R/ggplot newbie. I would like to create a geom_line plot of a continuous variable time series and then add a layer composed of events. The continuous variable and its timestamps is stored in one data.frame, the events and their timestamps are stored in another data.frame. 

What I would _really_ like to do is something like the charts on finance.google.com. In those, the time series is stock-price and there are &quot;flags&quot; to indicate news-events. I&#39;m not actually plotting finance stuff, but the type of graph is similar. I am trying to plot visualizations of log file data. Here&#39;s an example of what I mean...

![google chart with events][1]

If advisable (?), I would like to use separate data.frames for each layer (one for continuous variable observations, another for events).

After some trial and error this is about as close as I can get. Here, I am using example data from data sets that come with ggplot. &quot;economics&quot; contains some time-series data that I&#39;d like to plot and &quot;presidential&quot; contains a few events (presidential elections).
    
    library(ggplot2)
    data(presidential)
    data(economics)

    presidential &lt;- presidential[-(1:3),]
    yrng &lt;- range(economics$unemploy)
    ymin &lt;- yrng[1]
    ymax &lt;- yrng[1] + 0.1*(yrng[2]-yrng[1])
    
    p2 &lt;- ggplot()
    p2 &lt;- p2 + geom_line(mapping=aes(x=date, y=unemploy), data=economics , size=3, alpha=0.5) 
    p2 &lt;- p2 + scale_x_date(&quot;time&quot;) +  scale_y_continuous(name=&quot;unemployed [1000&#39;s]&quot;)
    p2 &lt;- p2 + geom_segment(mapping=aes(x=start,y=ymin, xend=start, yend=ymax, colour=name), data=presidential, size=2, alpha=0.5)
    p2 &lt;- p2 + geom_point(mapping=aes(x=start,y=ymax, colour=name ), data=presidential, size=3) 
    p2 &lt;- p2 + geom_text(mapping=aes(x=start, y=ymax, label=name, angle=20, hjust=-0.1, vjust=0.1),size=6, data=presidential)
    p2

![my attempt][2]


Questions: 

 * This is OK for very sparse events, but if there&#39;s a cluster of them (as often happens in a log file), it gets messy. Is there some technique I can use to neatly display a bunch of events occurring in a short time interval? I was thinking of position_jitter, but it was really hard for me to get this far. google charts stacks these event &quot;flags&quot; on top of each other if there&#39;s a lot of them.

 * I actually don&#39;t like sticking the event data in the same scale as the continuous measurement display. I would prefer to put it in a facet_grid. The problem is that the facets all must be sourced from the same data.frame (not sure if that&#39;s true). If so, that also seems not ideal (or maybe I&#39;m just trying to avoid using reshape?)



  [1]: http://i.stack.imgur.com/R4OWP.png
  [2]: http://i.stack.imgur.com/h6Sml.png

R + ggplot : Time series with events

I made a data.frame in R that is not very big, but it takes quite some time to build. I would to save it as a file, which I can than again open in R?

Content Type	Original Author	Original Content on Stackoverflow
Question	ahs85	View Question on Stackoverflow
Solution 1 - R	Andrie	View Answer on Stackoverflow

Format number as fixed width, with leading zeros

R Problem Overview

R Solutions

Solution 1 - R

Java regex email

What is Sliding Window Algorithm? Examples?

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