Is there a builtin type in julia equivalent to python None in Julia? [0, 1, false, 2, "", 3, 'a', 's', 34,[],missing] |> filter(func) # [ 1, 2, 3, 'a', 's', 34] What func could be. Why empty character '' is disallowed in Julia?

[image] VinodV: [0, 1, false, 2, “”, 3, ‘a’, ‘s’, 34,,missing] |> filter(func) julia> [0, 1, false, 2, "", 3, 'a', 's', 34,[],missing] |> filter(isnothing) Any[] julia> [0, 1, false, 2, "", 3, 'a', 's', 34,[],missing] |> filter(!isnothing) 11-element Vector{Any}: …

I don’t know what pattern you’re looking for, but maybe: julia> is_whatever(x::Number) = iszero(x) julia> is_whatever(x::AbstractString) = isempty(x) julia> is_whatever(x::AbstractArray) = isempty(x) julia> is_whatever(x::Missing) = true julia> is_whatever(x::Nothing) = true julia> is_whatever…

[image] VinodV: Why empty character '' is disallowed in Julia? There is no such thing as an empty character. There is an empty string which is a string with no characters.

The example code you gave uses the Python concept of “truthy”/“falsy” values, in which bool(x) returns false for empty containers and None and 0. Julia doesn’t have this concept: instead you can explicitly check the property you want, such as isempty or iszero.

Related discussion: [image] On the arbitrariness of truth(iness) Internals & Design Occasionally someone will be annoyed that Julia requires an actual true or false value in conditionals, whereas many dynamic languages (including Lisps) allow arbitrary values in conditions…

The high-level point that applies here is that I have no idea what you want those filter operations to do. Which elements did you want to keep? Why? I’m also a little confused what the example has to do with the Python None type…

An example might help, too: A string is roughly analogous to an array of integers. It makes sense to have an empty array of integers. For example, if it is mutable, remove all the elements. But it doesn’t make sense to talk about an empty integer. Both strings and arrays are variable length containe…

In addition to the previous answers, note that for most functions: missing silently propagate to missing (e.g. sum([1,2, missing]) evaluates to missing) nothing results in an error (e.g. sum([1,2, nothing]) results in an error when evaluated)

[image] jlapeyre: This is clearly an artifact of how characters are constructed, with two single quotes, eg 'c'. In Python (and Matlab, and perhaps others) strings can be created with single quotes, as well as with double quotes, unlike in Julia, where characters and strings are distinct. In …

Is there a builtin type in julia equivalent to python `None`?

General Usage

heliosdrm July 3, 2024, 5:56am 7

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Is there a builtin type in julia equivalent to python `None`?

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