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Install Java:
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer

Install Scala:
curl -O http://www.scala-lang.org/files/archive/scala-2.9.1-1.tgz
tar -xzf scala-2.9.1-1.tgz

sudo mv scala-2.9.1-1 /usr/share

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Installed Sharp keys and followed the instructions from here:
https://forums.virtualbox.org/viewtopic.php?f=8&t=63567#p298750

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## Installing Guest Additions on Debian
http://virtualboxes.org/doc/installing-guest-additions-on-debian/
Follow these steps to install the Guest Additions on your Debian virtual machine:
Login as root;
Update your APT database with apt-get update;
Install the latest security updates with apt-get upgrade;
Install required packages with apt-get install build-essential module-assistant;
Configure your system for building kernel modules by running m-a prepare;
Click on Install Guest Additions… from the Devices menu, then run mount /media/cdrom.

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hadoop fs -ls <>
hadoop fs -rmr 
..
use hadoop streaming to run python jobs

mapper reads from stdin and prints out the key and value

the sorted and shuffled output from mappers is given to reducers

since the input to reducers is sorted on the keys, some assumptions about the key read ordering can be made

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#In this case the blank cell are to be marked as NA. So have to tell R 
train.data = read.csv("train.csv", na.strings=c("NA", ""))

# taking data from dataframe based on condition : filtering data
train.data[which(train.data$Survived == 1),"Survived"])
length(train.data[which(train.data$Survived == 1 & train.data$Age > 50),"Survived"])
OR
length(train.data$Survived[train.data$Survived == 1 & train.data$Age > 50])

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Reference Cards
http://www.astro.up.pt/~sousasag/Python_For_Astronomers/Python_qr.pdf

Regular expression
https://developers.google.com/edu/python/regular-expressions?hl=en


Python Basics

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Problem:
When working in a specific context, i tend to open a number of screen windows and navigate between them. The open windows, with their names, make it lot easier to get into the context when i am at it again. 

Solution:
Create multiple screen config files, specific to each context and open them later when required
Create a base .screenrc with common config. Let the other screen config files source this
Add a bash function to open corresponding screen terminal

Procedure:
# create a folder to save the different screen configs

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Corpus
>> from nltk.corpus import brown
>>> brown.words()[0:10]

sentence & word tokenization
part-of-speech tagging
chunking & named entity recognition
text classification
many included corpora

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> brew install hadoop

This  installs hadoop at /usr/local/Cellar/hadoop/2.7.3

Find java home
> cd /usr/local/Cellar/hadoop/2.7.3
> vim etc/hadoop/hadoop-env.sh
The JAVA_HOME should be set as below in file
export JAVA_HOME="$(/usr/libexec/java_home)"

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# From http://www.cookbook-r.com/Graphs/Multiple_graphs_on_one_page_(ggplot2)/
#
#Multiple plot function
#
# ggplot objects can be passed in ..., or to plotlist (as a list of ggplot objects)
# - cols:   Number of columns in layout
# - layout: A matrix specifying the layout. If present, 'cols' is ignored.
#
# If the layout is something like matrix(c(1,2,3,3), nrow=2, byrow=TRUE),
# then plot 1 will go in the upper left, 2 will go in the upper right, and