The new syntax means the same thing but can be used in more circumstances and can express more constructs and eliminates a number of conceptual ambiguities, especially surrounding parametric constructors. The old syntax will be deprecated in 0.6 and some of the old syntax will be reclaimed with different meaning in 1.0. Fundamentally, the problem … Read more
Run Julia inside an IPython notebook Hack In order to run Julia snippets (or other language) inside an IPython notebook, I just append the string ‘julia’ to the default list in the _script_magics_default method from the ScriptMagics class in: /usr/lib/python3.4/site-packages/IPython/core/magics/script.py or /usr/lib/python2.7/site-packages/IPython/core/magics/script.py. Example: # like this: defaults = [ ‘sh’, ‘bash’, ‘perl’, ‘ruby’, ‘python’, ‘python2’, … Read more
You can use the vec() function. It’s faster than the list comprehension and scales better with number of elements š For a matrix of 1000×1: julia> const a = reshape([1:1000],1000,1); julia> typeof(a) Array{Int64,2} julia> vec_a = [x::Int for x in a]; julia> typeof(vec_a) Array{Int64,1} julia> vec_aII = vec(a); julia> typeof(vec_aII) Array{Int64,1} 6.41e-6 seconds # list … Read more
You can also go with filter!: a = Any[“D”, “A”, “s”, “t”] filter!(e->eā ”s”,a) println(a) gives: Any[“D”,”A”,”t”] This allows to delete several values at once, as in: filter!(e->eā[“s”,”A”],a) Note 1: In Julia 0.5, anonymous functions are much faster and the little penalty felt in 0.4 is not an issue anymore š . Note 2: Code above … Read more
The solution is relatively simple: x = Dict(“a”=>”A”, “b”=>”B”, “c”=>”C”) for (key, value) in x print(key); print(value) end # Output: cCbBaA Check out the Julia docs for Base.Dict to learn more about functions you can apply to a Dictionary in Julia!
If you want an array of arrays as opposed to a matrix (i.e. 2-dimensional Array): a = Array[ [1,2], [3,4] ] You can parameterize (specify the type of the elements) an Array literal by putting the type in front of the []. So here we are parameterizing the Array literal with the Array type. This … Read more
An Array{Bool} stores each true/false value as a Bool, which is represented internally as a UInt8. So if your array has N elements, it will take N bytes to store it. A BitArray stores each true/false value as a single bit, with (conceptually) 8 of them packed into a single UInt8. Consequently, it takes only … Read more
fields are simply the “components” of a struct. The struct struct A b c::Int end has the fields b and c. A call to getfield returns the object that is bound to the field: julia> a = A(“foo”, 3) A(“foo”, 3) julia> getfield(a, :b) “foo” In early versions of Julia, the syntax a.b used to … Read more
Use display(x). Let me comment here on what is going on here. A key difference is between show(io, x) and show(io, mime, x), as you can see in the docs: help?> show(stdout, a) show([io::IO = stdout], x) Write a text representation of a value x to the output stream io. New types T should overload … Read more
julia> a = [1, 2, 3, 4, 5]; julia> 6 ā a true The ā symbol can be typed in the REPL by typing \notin and then hitting TAB. Of course, the ā symbol is also available as an alternative to in by typing \in and hitting TAB: julia> 6 ā a false Sometimes you … Read more