[Question]
  [
Create a program that find the latest 50 challenges with the [code-golf](/questions/tagged/code-golf "show questions tagged 'code-golf'")-tag that have at least 20 answers. Then, extract the scores for each language in each of the challenges. If there are more than one answer using the same language, count all scores. Thereafter, take the top 20 most common languages and output a list with the language names, the number of answers, the average byte counts and the median byte counts. The list should be sorted by number of answers, in descending order. 
You must account for variations in capitalization (for instance: Matlab = MATLAB). 
In languages with many different version numbers (e.g. Python), count them as unique languages, so: `Python != Python 2 != Python 2.7 != Python 3.x` 
Example output (output format is optional):
```
cJam,       66,  12.4,  8.5
Pyth,       58,   15.2,  19
Ruby,       44,   19.2,  22.5
Python,     34,   29.3,  32
Python 2.7, 22,   31.2,  40
...
...
Java,       11,   115.5, 94.5
```
Header formats that must be supported:
* Starts with `# Language name,` or `#Language name`
* Ends with `xx bytes`, `xx Bytes` or just `xx`
* There can be a lot of garbage between the first comma and the last number.
* If the language name is a link (`[Name](link)`), it can be skipped
If the answer has another header format, you may choose to skip it (or include it if your code can handle it). 
As an example, all of the below headers must be supported:
```
# Language Name, N bytes
# Ruby, <s>104</s> <s>101</s> 96 bytes 
# Perl, 43 + 2 (-p flag) = 45 Bytes
# MATLAB, 5
```
Rules:
* It's OK to use API or just the website-url
	+ The following can be extracted from the byte count (nothing else), so no need to use a url-shortener (Maximum 44 bytes):
		- `https://` (or `http://`)
		- `codegolf`
		- `.stackexchange.com`
		- `/questions`
* The program can take input. The input will be included in the byte count.
Other than that, standard rules apply.
  
[Answer]
# R, 821 - 44 = 777 bytes
*Updated results*: please see the edit history to make sense of all the comments below.
```
           language num_answers avg_count median_count
1              RUBY          49  49.97959         30.0
2              CJAM          48  32.64583         22.0
3              PYTH          48  21.02083         14.0
4          PYTHON 2          46  86.78261         77.0
5             JULIA          43  58.90698         45.0
6           HASKELL          41  74.65854         56.0
7               PHP          40  73.52500         48.0
8              PERL          36  53.30556         34.0
9          PYTHON 3          34  90.91176         90.5
10       POWERSHELL          33  60.24242         44.0
11                C          32 221.84375         79.5
12                R          32  77.40625         62.5
13             JAVA          29 170.68966        158.0
14 JAVASCRIPT (ES6)          29  90.79310         83.0
15       JAVASCRIPT          28  68.39286         61.0
16               C#          25 193.92000        130.0
17      MATHEMATICA          23  56.04348         47.0
18           MATLAB          22  67.45455         55.0
19         TI-BASIC          19  47.05263         37.0
20              APL          18  16.55556         15.0
```
The code, which I could shorten a bit more:
```
W=library;W(XML);W(plyr)
X=xpathSApply;Y=xmlValue;D=data.frame;H=htmlParse;S=sprintf
Z="http://codegolf.stackexchange.com/"
R=function(FUN,...)do.call(rbind,Map(FUN,...))
G=function(url){d=H(url)
a=as.double(sub(".*?(\\d+)a.*","\\1",X(d,"//div[starts-with(@class,'status')]",Y)))
u=paste0(Z,X(d,"//*[contains(@class,'question-hyperlink')]",xmlGetAttr,"href"))
D(u,a)}
u=S("%s/questions/tagged/code-golf?page=%i",Z,1:50)
q=R(G,u)
u=with(q,head(u[a>20],50))
A=function(url){u=S("%s?page=%i",url,1:10)
f=function(u){d=H(u)
h=X(d, "//div[@class='post-text']//h1",Y)
p="^(.*?),.*? (\\d+)( [Bb]ytes)?$"
k=grep(p,h,v=T)
l=toupper(sub(p,"\\1",k))
c=as.double(sub(p,"\\2",k))
D(l,c)}
R(f,u)}
a=R(A,u)
L=names(tail(sort(table(a$l)),20))
x=subset(a,l%in%L)
arrange(ddply(x, "l",summarise,n=length(c),a=mean(c),m=quantile(c,0.5)),-n)
```
De-golfed:
```
library(XML)
library(plyr)
LoopBind <- function(FUN, ...) do.call(rbind, Map(FUN, ...))
GetQuestions <- function(url) {
  d = htmlParse(url)
  a=as.double(sub(".*?(\\d+)a.*","\\1",xpathSApply(d, "//div[starts-with(@class, 'status')]", xmlValue)))
  u=paste0("http://codegolf.stackexchange.com/",xpathSApply(d, "//*[contains(@class, 'question-hyperlink')]", xmlGetAttr, "href"))
  data.frame(u, a)
}
u <- sprintf("http://codegolf.stackexchange.com/questions/tagged/code-golf?page=%i", 1:50)
q <- do.call(rbind, Map(GetQuestions, u))
u <- with(q, head(u[a > 20], 50))
GetAnswers <- function(url) {
  u=sprintf("%s?page=%i",url,1:10)
  f=function(u) {
    d = htmlParse(u)
    h = xpathSApply(d, "//div[@class='post-text']//h1", xmlValue)
    p = "^(.*?),.*? (\\d+)( [Bb]ytes)?$"
    k = grep(p,h,v=T)
    l = toupper(sub(p,"\\1",k))
    c = as.double(sub(p,"\\2",k))
    data.frame(language=l,c)
  }
LoopBind(f,u)
}
a=LoopBind(GetAnswers, u)
L=names(tail(sort(table(a$l)),20))
x=subset(a,language%in%L)
arrange(ddply(x, "language", summarise, num_answers = length(c), avg_count = mean(c), median_count = quantile(c,0.5)),
        -num_answers)
```
[Answer]
# Python 2, 934 - 44 (url stuff) = 890 bytes
Using the API:
```
from urllib2 import urlopen as u
from gzip import GzipFile as f
from StringIO import StringIO as s;x="https://api.stackexchange.com/2.2%s&site=codegolf"
import re;j=u(x%'/search/advanced?pagesize=50&order=desc&sort=creation&answers=20&tagged=code-golf');q=s(j.read());g=f(fileobj=q);true=1;false=0;l=';'.join(str(a['question_id'])for a in eval(g.read())['items']);w=[]
def r(p):
 j=u(x%('/questions/%s/answers?page=%s&filter=!9YdnSMlgz&pagesize=100'%(l,p)));g.seek(0);q.truncate();q.write(j.read());q.seek(0);k=eval(g.read());w.extend(a['body_markdown']for a in k['items'])
 if k['has_more']:r(p+1)
r(1);x={};s=sorted
for m in w:
 try:
  l,n=re.match("(.*?),.*?([0-9]+)[^0-9]*$",m.splitlines()[0]).groups();l=re.subn("# ?","",l,1)[0].upper()
  if l not in x:x[l]=[]
  x[l]+=[(l,int(n))]
 except:pass
for l in s(x,cmp,lambda a:len(x[a]),1)[:20]:
 v=s(x[l])
 print l,len(v),sum(map(lambda a:a[1],v))/len(v),v[len(v)/2][1]
```
Note that this code **does not** pay attention to the API throttling.
Output:
```
RUBY 60 430 32
PYTH 57 426 16
CJAM 56 35 23
C 52 170 76
PYTHON 2 51 88 79
JULIA 42 63 48
HASKELL 42 81 63
JAVASCRIPT (ES6) 41 96 83
PERL 40 44 27
PYTHON 3 37 91 89
PHP 36 98 59
JAVASCRIPT 36 743 65
POWERSHELL 35 86 44
JAVA 32 188 171
R 30 73 48
MATLAB 25 73 51
MATHEMATICA 24 57 47
APL 22 14 13
SCALA 21 204 59
TI-BASIC 21 42 24
```
]