Functions with Strings

New to Julia
1

Hi All,

I am trying to build a function which takes words as the input and checks them against a table:

Colour = collect(“BROYWGIP”)

Colourtable = Table(name = [“Black”, “Red”, “Orange”, “Yellow”, “White”, “Green”, “Blue”, “Purple”], symbol = [Colour[1], Colour[2], Colour[3], Colour[4], Colour[5], Colour[6], Colour[7], Colour[8]], number = [0, 1, 2, 3, 4, 5, 6, 7])

function Check(x)
v = map(@Compute($name == x), Colourtable)
s = Int
for i in 1:8
if v[i] == true
push!(s,1)
elseif v[i] == false
push!(s,0)
else
return “Error”
end
end
a = Table(name = [“Black”, “Red”, “Orange”, “Yellow”, “White”, “Green”, “Blue”, “Purple”], present = [s[1],s[2],s[3],s[4],s[5],s[6],s[7],s[8]]),
b = Table(Colourtable; present = a.present)
end

I wrote the code as this but I am having an issue getting the initial variable x to be recognised in the v = map part.

Can anyone help suggest a work around? :slight_smile:

All the best,

2

Welcome! I cannot run your code, can you please follow the guidelines below?

1 Like
3

Thank you for responding, I have an issue running the code too, but the error comes from the Check(x). The possible inputs for x are supposed to be Black, Red, Orange, Yellow, White, Green, Blue, Purple. Anything else is supposed to return an error

I have tried to follow the guidelines:

using Tables, TypedTables

Colour = collect("BROYWGIP")

Colourtable = Table(name = ["Black", "Red", "Orange", "Yellow", "White", "Green", "Blue", "Purple"], symbol = [Colour[1], Colour[2], Colour[3], Colour[4], Colour[5], Colour[6], Colour[7], Colour[8]], number = [0, 1, 2, 3, 4, 5, 6, 7])

function Check(x)
	v = map(@Compute($name == x), Colourtable)
	s = Int[]
		for i in 1:8
			if v[i] == true
			push!(s,1)
			elseif v[i] == false
			push!(s,0) 
			else
			return "Error"
			end
		end
end

The additionally defined bits (a,b, and c) are just mappings I built to form a final table.

**Edit, the indentations are not working when I post into the forum. Is there a way around this?

4

Please use triple backticks around your code so that discourse can format it:
```
paste your code here
```

Also, include all packages needed to run your code.

5

There are a few issues with your present code:

  • collect(“BROYWGIP”): you have used an initial quote in the beginning, you must use " for the beginning and end of strings otherwise the first line will return an error (“BROYWGIP”)
  • The @Compute macro and Table type are not part of the standard library, if they are part of a package please specify which packages they belong to
  • Best to return an error via the @error macro, i.e. @error "<error message here>"
6

Hi M-Persic,

Thank you for coming back. I have corrected the thread to show the package (apologies first time using the forum)

the

collect("BRYWGIP")

returns an error when I use two single quotes, but provides a vector of size 8 when I use the double quote. perhaps this was a formating issue when I initially shows the code?

To help explain:

I want to build a map from colour to numbers. So if I have a colour that matches with one of the colours in the name row of the table, it will return a number vector.

Initially the number vector is in boolean (v), and so I convert it to a integer vector (s)

Finally I will want to glue the integer vector (s) to a copy of the table (Colourtable).

The ouptut of the function would be (ideally) the table produced by gluing the integer vector (s) to the table (Colourtable) copy

7

It seems to me like what you are doing should be a one or two-liner at most, but I struggle to see what exactly you are trying to do.

Maybe something like this?

julia> colour_dict = Dict(collect("BROYWGIP") .=> 0:7)
Dict{Char, Int64} with 8 entries:
  'P' => 7
  'I' => 6
  'Y' => 3
  'R' => 1
  'W' => 4
  'G' => 5
  'O' => 2
  'B' => 0

julia> get.(Ref(colour_dict), ['B', 'W', 'Z'], "Error")
3-element Vector{Any}:
 0
 4
  "Error"
3 Likes
8

Yes, in Julia, a pair of single quotes ’ ’ delimit a character (Char), whereas pair of double quotes " " or “”" “”" delimit string literals.

In this instance, we don’t know how the @Compute macro functions, so it’s hard to diagnose why it is spitting out errors.

9

Thank you Nilshg,

I am likely over complicating this as I get my head around the possible ways to code it!!

I will try this approach as well

10

I found the @Compute macro in this part of the manual:

https://typedtables.juliadata.org/stable/man/map/

:slight_smile:

11

you’re looking at the documentation of a package called TypedTable, not Julia’s own “manual”

1 Like
12

Have you taken a look at enums? They are built in or there is a package with extended functionality.