Convert Julia array to dataframe

Question

I have an array X that I'd like to convert to a dataframe. Upon recommendation from the web, I tried converting to a dataframe and get the following error.

julia> y=convert(DataFrame,x) ERROR:converthas no method matching convert(::Type{DataFrame}, ::Array{Float64,2}) in convert at base.jl:13

When I try DataFrame(x), the conversion works but i get a complaint that the conversion is deprecated.

julia> DataFrame(x) WARNING: DataFrame(::Matrix, ::Vector)) is deprecated, use convert(DataFrame, Matrix) instead in DataFrame at /Users/Matthew/.julia/v0.3/DataFrames/src/deprecated.jl:54 (repeats 2 times)

Is there another method I should be aware of to keep my code consistent?

EDIT: Julia 0.3.2, DataFrames 0.5.10 OSX 10.9.5

julia> x=rand(4,4)
4x4 Array{Float64,2}:
 0.467882   0.466358  0.28144   0.0151388
 0.22354    0.358616  0.669564  0.828768
 0.475064   0.187992  0.584741  0.0543435
 0.0592643  0.345138  0.704496  0.844822

julia> convert(DataFrame,x)
ERROR: `convert` has no method matching convert(::Type{DataFrame}, ::Array{Float64,2}) in convert at base.jl:13

spencerlyon2 · Accepted Answer · 2014-11-06 01:58:06Z

10

This works for me:

julia> using DataFrames

julia> x = rand(4, 4)
4x4 Array{Float64,2}:
 0.790912  0.0367989  0.425089  0.670121
 0.243605  0.62487    0.582498  0.302063
 0.785159  0.0083891  0.881153  0.353925
 0.618127  0.827093   0.577815  0.488565

julia> convert(DataFrame, x)
4x4 DataFrame
| Row | x1       | x2        | x3       | x4       |
|-----|----------|-----------|----------|----------|
| 1   | 0.790912 | 0.0367989 | 0.425089 | 0.670121 |
| 2   | 0.243605 | 0.62487   | 0.582498 | 0.302063 |
| 3   | 0.785159 | 0.0083891 | 0.881153 | 0.353925 |
| 4   | 0.618127 | 0.827093  | 0.577815 | 0.488565 |

Are you trying something different?

If that doesn't work try posting a bit more code we can help you better.

answered Nov 6, 2014 at 1:58

spencerlyon2

9,7364 gold badges33 silver badges41 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

colebrookson · Accepted Answer · 2022-03-01 10:53:37Z

9

Since this is the first thing that comes up when you google, for more recent versions of DataFrames.jl, you can just use the DataFrame() function now:

julia> x = rand(4,4)
4×4 Matrix{Float64}:
 0.920406  0.738911  0.994401  0.9954
 0.18791   0.845132  0.277577  0.231483
 0.361269  0.918367  0.793115  0.988914
 0.725052  0.962762  0.413111  0.328261

julia> DataFrame(x, :auto)
4×4 DataFrame
 Row │ x1        x2        x3        x4       
     │ Float64   Float64   Float64   Float64  
─────┼────────────────────────────────────────
   1 │ 0.920406  0.738911  0.994401  0.9954
   2 │ 0.18791   0.845132  0.277577  0.231483
   3 │ 0.361269  0.918367  0.793115  0.988914
   4 │ 0.725052  0.962762  0.413111  0.328261

answered Mar 1, 2022 at 10:53

colebrookson

9277 silver badges22 bronze badges

1 Comment

Refreshing Breeze Over a year ago

And DataFrame(x, ["col1", "col2", "col3", "col4"]) to set your own column names

Baum mit Augen · Accepted Answer · 2017-07-07 11:46:45Z

4

I've been confounded by the same issue a number of times, and eventually realized the issue is often related to the format of the array, and is easily resolved by simply transposing the array prior to conversion.

In short, I recommend:

julia> convert(DataFrame, x')

edited Jul 7, 2017 at 11:46

Baum mit Augen♦

50.4k25 gold badges153 silver badges187 bronze badges

answered Sep 2, 2016 at 0:05

lindsayhunter

411 bronze badge

Comments

JobJob · Accepted Answer · 2017-09-15 06:58:21Z

2

# convert a Matrix{Any} with a header row of col name strings to a DataFrame
# e.g. mat2df(["a" "b" "c"; 1 2 3; 4 5 6])

mat2df(mat) = convert(DataFrame,Dict(mat[1,:],
                     [mat[2:end,i] for i in 1:size(mat,2)]))

# convert a Matrix{Any} (mat) and a list of col name strings (headerstrings) 
# to a DataFrame, e.g. matnms2df([1 2 3;4 5 6], ["a","b","c"])

matnms2df(mat, headerstrs) = convert(DataFrame,
    Dict(zip(headerstrs,[mat[:,i] for i in 1:size(mat,2)])))

edited Sep 15, 2017 at 6:58

answered Dec 4, 2014 at 0:36

JobJob

4,1973 gold badges36 silver badges36 bronze badges

2 Comments

Frank Over a year ago

This no longer works under Julia v0.6.0 because you can't construct a Dict this way anymore. Replacing the Dict() calls with Dict(zip()) seems to work.

Antonello Over a year ago

Attention that if the Matrix to conver has mixed types, the converted DataFrame has all Any's (see stackoverflow.com/questions/46487261/…)

Kyle Protho · Accepted Answer · 2021-10-15 00:59:44Z

2

A little late, but with the update to the DataFrame() function, I created a custom function that would take a matrix (e.g. an XLSX imported dataset) and convert it into a DataFrame using the first row as column headers. Saves me a ton of time and, hopefully, it helps you too.

function MatrixToDataFrame(mat)
    DF_mat = DataFrame(
        mat[2:end, 1:end],
        string.(mat[1, 1:end])
    )
    return DF_mat
end

answered Oct 15, 2021 at 0:59

Kyle Protho

311 bronze badge

Comments

Josh Glaab · Accepted Answer · 2018-10-18 13:51:55Z

1

So I found this online and honestly felt dumb.

using CSV
WhatIWant = DataFrame(WhatIHave)

this was adapted from an R guide, but it works so heck

answered Oct 18, 2018 at 13:51

Josh Glaab

111 bronze badge

Comments

user17029991 · Accepted Answer · 2021-09-29 00:31:03Z

1

DataFrame([1 2 3 4; 5 6 7 8; 9 10 11 12], :auto)

This works as per >? DataFrame

answered Sep 29, 2021 at 0:31

user17029991

111 bronze badge

Collectives™ on Stack Overflow

Convert Julia array to dataframe

7 Answers 7

Comments

1 Comment

Comments

2 Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

Comments

1 Comment

Comments

2 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related