`expression` is your friend:


    plot(1,1, main=expression(&#39;title&#39;^2))  #superscript
    plot(1,1, main=expression(&#39;title&#39;[2])) #subscript

If you are looking to have multiple subscripts in one text then use the star(*) to separate the sections:

    plot(1:10, xlab=expression(&#39;hi&#39;[5]*&#39;there&#39;[6]^8*&#39;you&#39;[2]))

See ?expression

    plot(1:10,main=expression(&quot;This is a subscript &quot;[2]))

![enter image description here][1]


  [1]: http://i.stack.imgur.com/9OASX.jpg


A subscript and referring to a stored value...

    a &lt;- 10
    plot(c(0,1), c(0,1), type = &#39;n&#39;, ann = FALSE, xaxt = &#39;n&#39;, yaxt = &#39;n&#39;)
    text(0.2, 0.6, cex = 1.5, bquote(paste(&#39;S&#39;[&#39;f&#39;]*&#39; = &#39;, .(a))))

[![enter image description here][1]][1]


  [1]: http://i.stack.imgur.com/QFjMi.jpg

Another example, expression works for negative superscripts without the need for quotes around the negative number:

    title(xlab=expression(&quot;Nitrate Loading in kg ha&quot;^-1*&quot;yr&quot;^-1))

and you only need the * to separate sections as mentioned above (when you write a superscript or subscript and need to add more text to the expression after). 

As other users have pointed out, we use `expression()`. I&#39;d like to answer the original question which involves a comma in the subscript:
&gt; *How can I write v 1,2 with 1,2 as subscripts?*

    plot(1:10, 11:20 , main=expression(v[&quot;1,2&quot;]))

Also, I&#39;d like to add the reference for those looking to find the full `expression` syntax in `R` plotting: For more information see the `?plotmath` help page. Running `demo(plotmath)` will showcase many expressions and relevant syntax.

Remember to use `*` to join different types of text within an expression.

Here is some of the sample output from `demo(plotmath)`:

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/kcx1Y.png

I am searching through a Git repository and would like to include the `.git` folder.

`grep` does not include this folder if I run

    grep -r search *

What would be a grep command to include this folder?


How can I grep hidden files?

I want to split up my routes into different files, where one file contains all routes and the other one the corresponding actions. I currently have a solution to achieve this, however I need to make the app-instance global to be able to access it in the actions.
My current setup looks like this:

app.js:

    var express   = require(&#39;express&#39;);
    var app       = express.createServer();
    var routes    = require(&#39;./routes&#39;);

    var controllers = require(&#39;./controllers&#39;);
    routes.setup(app, controllers);

    app.listen(3000, function() {
      console.log(&#39;Application is listening on port 3000&#39;);
    });

routes.js:

    exports.setup = function(app, controllers) {
    
      app.get(&#39;/&#39;, controllers.index);
      app.get(&#39;/posts&#39;, controllers.posts.index);
      app.get(&#39;/posts/:post&#39;, controllers.posts.show);
      // etc.
    
    };

controllers/index.js:

    exports.posts = require(&#39;./posts&#39;);
    
    exports.index = function(req, res) {
      // code
    };

controllers/posts.js:

    exports.index = function(req, res) {
      // code
    };
    
    exports.show = function(req, res) {
      // code
    };

However, this setup has a big issue: I have a database- and an app-instance I need to pass to the actions (controllers/*.js). The only option I could think of, is making both variables global which isn&#39;t really a solution. I want to separate routes from the actions because I have a lot of routes and want them in a central place.

What&#39;s the best way to pass variables to the actions but separate the actions from the routes?

Express: How to pass app-instance to routes from a different file?

I can&#39;t find a way how to write subscripts in the title or the subtitle in R.
How can I write v 1,2 with 1,2 as subscripts?

Thanks for your help!

Subscripts in plots in R

<p>I can't find a way how to write subscripts in the title or the subtitle in R.
How can I write v 1,2 with 1,2 as subscripts?</p>
<p>Thanks for your help!</p>


I&#39;m having a little trouble understanding the pass-by-reference properties of `data.table`. Some operations seem to &#39;break&#39; the reference, and I&#39;d like to understand exactly what&#39;s happening.

On creating a `data.table` from another `data.table` (via `&lt;-`, then updating the new table by `:=`, the original table is also altered. This is expected, as per:

`?data.table::copy`
and [stackoverflow: pass-by-reference-the-operator-in-the-data-table-package](&lt;https://stackoverflow.com/questions/8030452/pass-by-reference-the-operator-in-the-data-table-package&gt;)

Here&#39;s an example:

    library(data.table)

    DT &lt;- data.table(a=c(1,2), b=c(11,12))
    print(DT)
    #      a  b
    # [1,] 1 11
    # [2,] 2 12

    newDT &lt;- DT        # reference, not copy
    newDT[1, a := 100] # modify new DT

    print(DT)          # DT is modified too.
    #        a  b
    # [1,] 100 11
    # [2,]   2 12

However, if I insert a non-`:=` based modification between the `&lt;-` assignment and the `:=` lines above, `DT` is now no longer modified:

    DT = data.table(a=c(1,2), b=c(11,12))
    newDT &lt;- DT        
    newDT$b[2] &lt;- 200  # new operation
    newDT[1, a := 100]

    print(DT)
    #      a  b
    # [1,] 1 11
    # [2,] 2 12

So it seems that the `newDT$b[2] &lt;- 200` line somehow &#39;breaks&#39; the reference. I&#39;d guess that this invokes a copy somehow, but I would like to understand fully how R is treating these operations, to ensure I don&#39;t introduce potential bugs in my code.

I&#39;d very much appreciate if someone could explain this to me.

Understanding exactly when a data.table is a reference to (vs a copy of) another data.table

I am on R version 2.13 and would like to update to a newer version in order to use some packages that depend on R&gt;= 2.14. 

I have the line to my sources.list file as found described [here][1].  I then navigate to the terminal and type:

    sudo apt-get update

and get the following error when trying to update R on the CRAN mirror closest to me:

&gt;Reading package lists... Done
&gt;
W: GPG error: http://lib.stat.cmu.edu oneiric/ Release: The following signatures couldn&#39;t be verified because the public key is not available: NO_PUBKEY 51716619E084DAB9

Any idea how to debug this error?


  [1]: http://cran.r-project.org/bin/linux/ubuntu/

Installing R from CRAN Ubuntu repository: No Public Key Error

I want to copy/paste a file from one folder to another folder in windows using R, but it&#39;s not working.  My code:

    &gt; file.rename(from=&quot;C:/Users/msc2/Desktop/rabata.txt&quot;,to=&quot;C:/Users/msc2/Desktop/Halwa/BADMASHI/SCOP/rabata.tx&quot;)

    [1] FALSE

Moving files between folders

I have a data.frame with the name &quot;abcframe&quot; 

         a  b  c
         1  1  1
         2  2  3

How might I find whether a column exists or not in a given data frame?
For example, I would like to find whether a **column d** exists in the data.frame **abcframe**.

To find whether a column exists in data frame or not

I am trying to get the x axis labels to be rotated 45 degrees on a barplot with no luck. This is the code I have below:

    barplot(((data1[,1] - average)/average) * 100,
            srt       = 45,
            adj       = 1,
            xpd       = TRUE,
            names.arg = data1[,2],
            col       = c(&quot;#3CA0D0&quot;),
            main      = &quot;Best Lift Time to Vertical Drop Ratios of North American Resorts&quot;,
            ylab      = &quot;Normalized Difference&quot;,
            yaxt      = &#39;n&#39;,
            cex.names = 0.65,
            cex.lab   = 0.65)



Rotating x axis labels in R for barplot

I&#39;m trying to generate a 3D scatter plot using Matplotlib. I would like to annotate individual points like the 2D case here:
https://stackoverflow.com/questions/5147112/matplotlib-how-to-put-individual-tags-for-a-scatter-plot.

I&#39;ve tried to use this function and consulted the Matplotlib docoment but found it seems that the library does not support 3D annotation. Does anyone know how to do this?

Thanks!

Matplotlib: Annotating a 3D scatter plot

I need to add two subplots to a figure. One subplot needs to be about three times as wide as the second (same height). I accomplished this using `GridSpec` and the `colspan` argument but I would like to do this using `figure` so I can save to PDF. I can adjust the first figure using the `figsize` argument in the constructor, but how do I change the size of the second plot?

Matplotlib different size subplots

I am playing in Python a bit again, and I found a neat book with examples. One of the examples is to plot some data. I have a .txt file with two columns and I have the data. I plotted the data just fine, but in the exercise it says: Modify your program further to calculate and plot the running average of the data, defined by:

    $Y_k=\frac{1}{2r}\sum_{m=-r}^r y_{k+m}$

where `r=5` in this case (and the `y_k` is the second column in the data file). Have the program plot both the original data and the running average on the same graph.

So far I have this:

    from pylab import plot, ylim, xlim, show, xlabel, ylabel
    from numpy import linspace, loadtxt
    
    data = loadtxt(&quot;sunspots.txt&quot;, float)
    r=5.0
    
    x = data[:,0]
    y = data[:,1]
    
    plot(x,y)
    xlim(0,1000)
    xlabel(&quot;Months since Jan 1749.&quot;)
    ylabel(&quot;No. of Sun spots&quot;)
    show()

So how do I calculate the sum? In Mathematica it&#39;s simple since it&#39;s symbolic manipulation (Sum[i, {i,0,10}] for example), but how to calculate sum in python which takes every ten points in the data and averages it, and does so until the end of points?

I looked at the book, but found nothing that would explain this :\

-----------------------------

heltonbiker&#39;s code did the trick ^^ :D


    from __future__ import division
    from pylab import plot, ylim, xlim, show, xlabel, ylabel, grid
    from numpy import linspace, loadtxt, ones, convolve
    import numpy as numpy
    
    data = loadtxt(&quot;sunspots.txt&quot;, float)
    
    def movingaverage(interval, window_size):
        window= numpy.ones(int(window_size))/float(window_size)
        return numpy.convolve(interval, window, &#39;same&#39;)
    
    x = data[:,0]
    y = data[:,1]
    
    
    plot(x,y,&quot;k.&quot;)
    y_av = movingaverage(y, 10)
    plot(x, y_av,&quot;r&quot;)
    xlim(0,1000)
    xlabel(&quot;Months since Jan 1749.&quot;)
    ylabel(&quot;No. of Sun spots&quot;)
    grid(True)
    show()

And I got this: 

![image][1]

Thank you very much ^^ :)


  [1]: http://i.stack.imgur.com/4TyaF.png

Finding moving average from data points in Python

What is the difference between 
matplotlib.pyplot and matplotlib.pylab?

Which is preferred for what usage?

I am a little confused, because it seems like independent from which I import, I can do the same things. What am I missing?

What is the difference between pylab and pyplot?

Is there a way to slice only the first and last item in a list?

For example; If this is my list:

    &gt;&gt;&gt; some_list
    [&#39;1&#39;, &#39;B&#39;, &#39;3&#39;, &#39;D&#39;, &#39;5&#39;, &#39;F&#39;]

I *want* to do this (obviously `[0,-1]` is not valid syntax):

    &gt;&gt;&gt; first_item, last_item = some_list[0,-1]
    &gt;&gt;&gt; print first_item
    &#39;1&#39;
    &gt;&gt;&gt; print last_item
    &#39;F&#39;

Some things I have tried:

    In [3]: some_list[::-1]
    Out[3]: [&#39;F&#39;, &#39;5&#39;, &#39;D&#39;, &#39;3&#39;, &#39;B&#39;, &#39;1&#39;]

    In [4]: some_list[-1:1:-1]
    Out[4]: [&#39;F&#39;, &#39;5&#39;, &#39;D&#39;, &#39;3&#39;]
    
    In [5]: some_list[0:-1:-1]
    Out[5]: []
    ...



Python slice first and last element in list

I&#39;m aware that R markdown can produce superscripts:

    text^superscript

But is it possible to produce proper subscripts? Or is the only way to do so to cheat and use `LaTeX` math mode:

    $\sf{text_{subscript}}$

The intended final output is HTML.

Producing subscripts in R markdown

 I&#39;ve found some letters but i need to find others such as &quot;c&quot;, &quot;m&quot;, &quot;p&quot;, is this even possible? 

How to find the unicode of the subscript alphabet?

How can I get the nth character of a string? I tried bracket(`[]`) accessor with no luck. 


    var string = &quot;Hello, world!&quot;
    
    var firstChar = string[0] // Throws error

 &gt; ERROR: &#39;subscript&#39; is unavailable: cannot subscript String with an Int, see the documentation comment for discussion

Get nth character of a string in Swift programming language

In Swift 4, I&#39;m getting this error when I try to take a ``Substring`` of a ``String`` using subscript syntax.

&gt; &#39;subscript&#39; is unavailable: cannot subscript String with a CountableClosedRange&lt;Int&gt;, see the documentation comment for discussion

For example:

    let myString: String = &quot;foobar&quot;
    let mySubstring: Substring = myString[1..&lt;3]

Two questions:

1. How can I resolve this error?
2. Where is &quot;the documentation comment for discussion&quot; that was referred to in the error?

Content Type	Original Author	Original Content on Stackoverflow
Question	jeffrey	View Question on Stackoverflow
Solution 1 - R	smu	View Answer on Stackoverflow
Solution 2 - R	Cyrille	View Answer on Stackoverflow
Solution 3 - R	Chase	View Answer on Stackoverflow
Solution 4 - R	Tony Ladson	View Answer on Stackoverflow
Solution 5 - R	user29609	View Answer on Stackoverflow
Solution 6 - R	Megatron	View Answer on Stackoverflow

Subscripts in plots in R

R Problem Overview

R Solutions

Solution 1 - R

Solution 2 - R

Solution 3 - R

Solution 4 - R

Solution 5 - R

Solution 6 - R

Express: How to pass app-instance to routes from a different file?

How can I grep hidden files?

Attributions