Some interesting Julia codes

Julia is fast, composable, dynamic, general, reproducible and open source. The codes below were taken from https://julialang.org. I found it very illustrating.

Multiple dispatch

struct Dog end
struct Cat end

dog, cat = Dog(), Cat()
meet(a::Dog, b::Dog) = "The dogs play together"
meet(a::Dog, b::Cat) = "The dog chases the cat"
meet(a::Cat, b::Dog) = "The cat hisses at the dog"
meet(a::Cat, b::Cat) = "The cats ignore each other"

meet(dog, cat)
meet(dog, dog)
meet(cat, cat)

Display customization

struct Nutshell{T}
	contents::T
end
Base.show(io::IO, n::Nutshell) = print(io, "🥜 ", n.contents, " 🥜")
Nutshell("Julia")

Unicode and math

α, β = .5, .3
f(x) = α * x + β
Σ(v) = reduce(+, v)
Σ(f.(1:5))

Comprehensions

[x^2 for x in 1:5]

Broadcasting

A = [1 2; 3 4]
sin.(A) .+ 1
Dict(c => i for (i, c) in enumerate("julia")

Piping and composition

1:5 |> sum |> sqrt
(sqrt ∘ sum)(1:5) # equiv. above
map(exp ∘ abs, [-1, 2, -3])

Destructuring

(a, b, c) = 1:3
a, c # => (1, 3)
head, tail... = ["first", "second", "third"]
head, tail # => ("first", ["second", "third"])

Metaprogramming

ex = :(1 + 2 * 3)
typeof(ex) # => Expr
eval(ex)   # => 7

Easy package install

using DataFrames
# if not installed, prompted for installation, after 'y' answer
df = DataFrame(name = ["Alice", "Bob"], age = [25, 30])

Defaults and keywords args

function greet(name, greeting = "Hello"; punctuation = "!")
	"$greeting, $name$puctuation"
end
greet("Julia")  # "Hello, Julia!"
greet("world", "Hi"; puctuation = ".") # "Hi, world."

Multi-threading

function fib(n)
	n < 2 && return n
	t = Threads.@spawn fib(n-2)
	return fib(n-1) + fetch(t)
end
fib(10)
Threads.nthreads() # => threads assigned to Julia

Build-in REPL modes

# Default Julia mode, backspace from other modes
# Press ] for package mode
# Press ; for shell mode
# Press ? for helps
# Press $ for R mode, if RCall.jl is installed

Code introspection (simplified)

f(x, y) = x + y
@code_warntype f(1, 2)
@code_llvm f(1, 2)
@code_native f(1, 2)

Running ASReml on Linux

To run ASReml on a Linux system can be very tricky. This software has built its reputation. It then don’t care very much about its custormers. The following valid instructions were after many combination tests. Had you any other alternatives, I would not recommend ASReml, especially on Linux, where most serious computations are carried on nowadays.

The following instructions are to run a cloud instance of AlmaLinux9 one a AlmaLinux 10 system.

Resize root partition on an AlmaLinux OS

Resizing Root Partition on AlmaLinux 10 (LVM + XFS)

Since XFS filesystems cannot be shrunk, increasing the root partition requires backing up the /home partition, deleting it, expanding /root, and then recreating /home.

Prerequisites

A backup location with enough space (e.g., /mnt/w).
Root or sudo access.

Step 1: Backup Home Data

Backup all data from /home to a temporary location.

sudo mkdir -p /mnt/w/home_backup
sudo rsync -aHAX --progress /home/ /mnt/w/home_backup/

Step 2: Unmount and Remove the Home Volume

Ensure no processes are using /home, then unmount it and remove the Logical Volume (LV).

Breeding and genetics