nilforooshan

Access GitHub on EC2

• On the EC2 instance, type ssh-keygen.
• Got to: GitHub » Settings » SSH and GPG keys » New SSH Key
• Give it a title and copy the contents of ~/.ssh/id_rsa.pub in the EC2 into the Key box.
• To check the success, type ssh git@github.com on the EC2.

nilforooshan

get & assign

This simple example illustrates the usage of get and assign commands in R.

test1 = 1:10
test2 = 10:1
for(i in 1:2)
{
 tmp = get(paste0("test", i))

nilforooshan

Export a Jupyter notebook to HTML

jupyter nbconvert --to html notebook.ipynb

Source

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Install pip on Ubuntu

sudo apt install python3-pip -y

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Various ways of selecting multiple columns in a data.table

An example data.table:

DT = data.table(
    ID = c("b","b","b","a","a","c"),
    a = 1:6,
    b = 7:12,
 c = 13:18

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Replace NA with 0 in a range of columns

In this example, NA is replaced with 0 in the last two columns.

ped
#   id sire dam
# 1  1    6  11
# 2  2   NA  12
# 3 3 8 NA

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Renaming columns with their name ending with a pattern

Merging two data frames sharing columns with the same name, those columns will receive .x and .y suffixes for the first and the second merged data frame. Follow this example to renew those columns.

(test <- data.frame(a = 1:5, b.x = 6:10, b.y = 11:15, c.x = 16:20, c.y = 21:25))

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Remove leading 0s in an array of strings

id <- c("00001","00010","00022","07432")
as.character(as.integer(id))

[1] "1"    "10"   "22"   "7432"

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Export an R Jupyter notebook to RMD

filename <- "FILENAME"
fileConn <- file(paste0(filename, '.rmd'))
writeLines(xfun::file_string(rmarkdown:::convert_ipynb(paste0(filename, '.ipynb'))), fileConn)
close(fileConn)

The following will also do:

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Replace the upper triangle of a covariance matrix with a correlation matrix

(x <- matrix(c(1,0.2,0.5,1.2,0.2,2,0.5,1,0.5,0.5,3,1.6,1.2,1,1.6,4), nrow = 4))

     [,1] [,2] [,3] [,4]
[1,]  1.0  0.2  0.5  1.2
[2,] 0.2 2.0 0.5 1.0