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
You can use the vec() function. It’s faster than the list comprehension and scales better with number of elements 😉 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
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
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 ∉ a true The ∉ symbol can be typed in the REPL by typing \notin and then hitting TAB. Of course, the ∈ symbol is also available as an alternative to in by typing \in and hitting TAB: julia> 6 ∈ a false Sometimes you … Read more
The easiest thing to do is readline(stdin). Is that what you’re looking for?
Julia has the isfile() function to test for a regular file: julia> isfile(“foo.txt”) false shell> touch foo.txt julia> isfile(“foo.txt”) true As the documentation: Returns true if path (the parameter) is a regular file, false otherwise.
In Julia, the equivalent to list.files() is readdir([path]) There is no built-in directory search that I know of, but it is a one-liner: searchdir(path,key) = filter(x->contains(x,key), readdir(path)) UPDATE: Since at least Julia v0.7, contains() has been deprecated for occursin(substring, string). So the above filter would now be: searchdir(path,key) = filter(x->occursin(key,x), readdir(path))
@ChrisRackauckas’s answer is accurate as far as it goes – i.e. for mutable objects. There’s a bit more to the issue than that, however, so I’ll elaborate a bit here. The === operator (an alias for the is function) implements Henry Baker’s EGAL predicate [1, 2]: x === y is true when two objects are programmatically … Read more