juliapluto.jl

Pluto.jl throws a multiple assigning error when trying to change the values of a variable

In Python, if you have a variable numbers = 5 and then in the next like you write numbers = 55, the variable's value is updated.

While using Pluto.jl, I declared a variable called y_axis. I decided to change the value of this variable in another cell but I am getting this error:

Multiple definitions for y_axis.

Combine all definitions into a single reactive cell using a `begin ... end` block.

Why doesn't Pluto.jl let me change a variable? Let me show you exactly what I am talking about. This is the 1st cell:

begin
    
    countries_data_labels = ["Italy", "Germany", "Pakistan", "Turkey", "United Kingdom"];
    
    y_axis = DataFrame() # Creating an empty dataframe to populate the y-axis when plotting graphs.
    
    ...
end

And this is 2 cells below:

begin
    ...

    y_axis = select!(y_axis, Not([:One_million]));
end

I'm sure Pluto allows changing a variable without having to create a giant block of a cell but I don't know how.

Solution

  • This is covered in the Pluto FAQ:

    How can I modify a variable in a different cell?

    Variables can only be assigned and modified in a single cell. This is what makes reactivity possible

    https://github.com/fonsp/Pluto.jl/wiki/%E2%9A%A1-Writing-and-running-code

    If you are used to a different workflow from python, consider using jupyter Notebooks via IJulia.