Replace the 4th character with another letter.

echo "abcdefghijklmnop" | sed 's/./X/4'

Using Rpy2 with Anaconda and Ipython notebook

Typically in ipython notebook, the only command required to print a plot inline is the following:

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%load_ext rmagic
=====================

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%%R 
x<-c(1,2,3)
y<-c(2,3,4)
plot(x,y)

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While working on AWS, my plots would not show up inline. I found out that this is because rpy2 only works for python 2.7.5. 

The easy fix is 

conda install python=2.7.5=2