Chapter 2 - Feedback

[dhassault]

Hi o/

First of all, thank you for this book! It's super interesting! I'm going trough it now so I was thinking that it would be useful for you to give you some feedback. I'm using https://datasciencejuliahackers.com/ and Julia 1.6, total beginner in Julia but used python and the data science ecosystem for several years.

1. In several strings there are many \ like println(\"x is greater than 2\") which generates an error
2. I didn't get the explanation of single and multiple dispatched
3. Some characters are not showed properly
   Like In general, unicode characters are activated by using ’‘, followed by the name of the character and then pressing the ’tab’ key. -> by using ’‘,

Otherwise on 2.5.2:

4. There is a typo in the following sentence
   each column represents a a realization of a variable
   The "a a".
5. No instructions for installing DataFrames.jl and CSV
6. ArgumentError with sample code

ArgumentError: `DataFrame` constructor from a `Matrix` requires passing :auto as a second argument to automatically generate column names: `DataFrame(matrix, :auto)`

    DataFrames.DataFrame(::Matrix{Float64})@dataframe.jl:363
    top-level scope@Local: 9
begin
    using DataFrames, Random
    
    Random.seed!(123)
    
    fake_data = rand(5, 5) # this creates a 5x5 matrix with random values between 0 
                           # and 1 in each matrix element.
    
    df = DataFrame(fake_data)
end

7. It felt slightly confusing to jump from a Dataframe and suddenly re-use a previous one like:
   We initialized df_:

## 1×3 DataFrame
##  Row │ Names   Countries  Ages
##      │ String  String     Int64
## ─────┼──────────────────────────
##    1 │ Juan    Argentina     28

Then the next code sample uses df.three:

## 5-element Array{Float64,1}:
##  0.16366581948600145
##  0.4730168160953825
##  0.8654121434083455
##  0.617491887982287
##  0.2856979003853177

It makes sense considering the next code samples but I felt it could be confusing.

[unbalancedparentheses]

@dhassault first of all thank you very much for taking the time to read the book and for the the feedback. We will fix many of the things you mentioned during the week. Thanks again!