Using CSV.read() to import data from a data input file into a DataFrame

General Usage
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1

In my homemade function ‘readdata()’ I have:
Data = csv.read(filename; delim=‘,’, DataFrame)
where ‘filename’ refers to one of my data inputfiles, named e.g. ‘instance.txt’.
This resulted from my code in julia-1.0.

When I try to run this, ‘Data’ remains empty; I cannot extract data from it.

2

You are getting keyword arguments and positional arguments mixed up

CSV.read(filename, DataFrame; delim = ',')
3

When I do that I get the following:

Data = CSV.read(filename, DataFrame; delim=‘,’)

#function read(source, sink=nothing; copycols::Bool=false, kwargs…)
#if sink === nothing
#Data = CSV.read(filename; delim=‘,’, DataFrame)
#end
#Tables.CopiedColumns(CSV.File(source; kwargs…)) |> sink
#end

What to do with it?

4

You get 6 comments ?

5

First you should try this.

6

I got this comment:

‘’’
#function read(source, sink=nothing; copycols::Bool=false, kwargs…)
…#if sink === nothing
…#Data = CSV.read(filename; delim=‘,’, DataFrame)
…#end
…#Tables.CopiedColumns(CSV.File(source; kwargs…)) |> sink
#end
‘’’

7

```
type the code here
```

8 
#function read(source, sink=nothing; copycols::Bool=false, kwargs…)
..#if sink === nothing
....#Data = CSV.read(filename; delim=’,’, DataFrame)
..#end
..#Tables.CopiedColumns(CSV.File(source; kwargs…)) |> sink
#end
9

I copied the comment (with 6 lines). The indentation and my triple backtics disappeared.

10

you are not describing the problem you are encountering in your code

11

After my code line ‘Data = CSV.read(filename, DataFrame; delim=‘,’)’ Julia inserted 6 lines of code, all commented.
I didn’t know what to do with it, because I don’t understand what these 6 lines do.

When I uncomment them, and try to extract a collumn from Data by ‘x = Data[:1]’ Iget ‘UndefVarError: Data not defined’.

12

Run the following code:

df = DataFrame(a = [1, 2], b = [3, 4])
CSV.write("file.csv", df)
df_new = CSV.read("file.csv", DataFrame)
13

Julia is not inserting those comments anywhere. Some other program might be, an editor maybe?

Exactly how are you running the command?

14

The commented code is broken, it looks like two code fragments randomly pasted together.

in addition, Data[:1] is not valid code either

what you should be getting is

julia> Data[:1]
ERROR: ArgumentError: syntax Data[column] is not supported use df[!, column] instead
...
15

Thank you! I’m nearly there, but not quite.
I have 5 collumns in my data file, and the first 4 went through.
So I changed naively [3, 4] into [3, 4, 5], but that didn’t work

16

Can you share the file? Or at least copy and paste the first few lines?

17

1511805.54010775,-3631401.61267572,134,14.0385102411102,1.58792636637882
1511880.54010775,-3631401.61267572,135,14.0623467964249,1.63997535275912
1511955.54010775,-3631401.61267572,136,13.8401810265915,1.48364309144577
1511730.54010775,-3631476.61267572,248,14.3080113191324,1.8129535268525
1511805.54010775,-3631476.61267572,249,14.2710283891669,1.78019664985144
1511880.54010775,-3631476.61267572,250,14.2895778872987,1.79291534883922
1511955.54010775,-3631476.61267572,251,13.9846463218381,1.55426381397442
1512030.54010775,-3631476.61267572,252,13.1978960888864,1.12702376308933
1512105.54010775,-3631476.61267572,253,12.0766192975667,0.867366055025797

18

Works perfectly for me.

19

Could you also extract the last column?

20

I run this via VSCode