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

**URL:** <https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120>\
**Category:** General Usage\
**Tags:** question, dataframes, csv\
**Created:** [February 26, 2022, 12:54pm UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120 "2022-02-26T12:54:33Z")\
**Posts on this page:** 8\
**Page:** 2

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**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [February 28, 2022, 1:35am UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/21 "2022-02-28T01:35:35Z")

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Yes, the 5th column worked.

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<div class="post-metadata">

**Author:** ![nilshg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nilshg/32/2283_2.png) [@nilshg](https://discourse.julialang.org/u/nilshg)\
**Post date:** [February 28, 2022, 8:38am UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/22 "2022-02-28T08:38:49Z")

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Just to show what Peter meant:

```julia
julia> using DataFrames, CSV

julia> data = """
       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
       """
"1511805.54010775,-3631401.61267572,134,14.0385102411102,1.58792636637882\n1511880.54010775,-3631401.61267572,135,14.0623467964249,1.63997535275912\n1511955.54010775,-3631401.61267572,136,13.8401810265915,1.48364309144577\n1511730.54010775,-3631476.61267572,248,14.3080113191324,1.8129535268525\n1511805.54010775,-3631476.61267572,249,14.2710283891669,1.78019664985144\n1511880.54010775,-3631476.61267572,250,14.2895778872987,1.79291534883922\n1511955.54010775,-3631476.61267572,251,13.9846463218381,1.55426381397442\n1512030.54010775,-3631476.61267572,252,13.1978960888864,1.12702376308933\n1512105.54010775,-3631476.61267572,253,12.0766192975667,0.867366055025797\n"

julia> CSV.read(IOBuffer(data), DataFrame; delim = ",", header = false)
9×5 DataFrame
 Row │ Column1 Column2 Column3 Column4 Column5  
     │ Float64 Float64 Int64 Float64 Float64  
─────┼───────────────────────────────────────────────────
   1 │ 1.51181e6 -3.6314e6 134 14.0385 1.58793
   2 │ 1.51188e6 -3.6314e6 135 14.0623 1.63998
   3 │ 1.51196e6 -3.6314e6 136 13.8402 1.48364
   4 │ 1.51173e6 -3.63148e6 248 14.308 1.81295
   5 │ 1.51181e6 -3.63148e6 249 14.271 1.7802
   6 │ 1.51188e6 -3.63148e6 250 14.2896 1.79292
   7 │ 1.51196e6 -3.63148e6 251 13.9846 1.55426
   8 │ 1.51203e6 -3.63148e6 252 13.1979 1.12702
   9 │ 1.51211e6 -3.63148e6 253 12.0766 0.867366

```

Here I’m just reading the data from an `IOBuffer`, but equally I can write this out to a file and read back in from disk:

```julia
# df is the DataFrame I read in above
julia> CSV.write("test.csv", df)
"test.csv"

julia> CSV.read("test.csv", DataFrame; delim = ",")
# Same result as above (although the file written to disk has a header now, so I removed header=false here

```

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<div class="post-metadata">

**Author:** ![jjdegruijter](https://avatars.discourse-cdn.com/v4/letter/j/fbc32d/32.png) [@jjdegruijter](https://discourse.julialang.org/u/jjdegruijter)\
**Post date:** [February 28, 2022, 4:15pm UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/23 "2022-02-28T16:15:37Z")

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In my function readdata() I have:  
df = DataFrame(a= [1, 2], b = [3, 4])  
CSV.write(“file.csv”, df)  
df\_new = CSV(“file.csv”, DataFrame)  
Data = CSV.read(filename, DataFrame; delim=‘,’, header=false)

When I run this I get a lot of text from ‘abstractdataframe.jl’ where one line is highligjhted:  
“syntax df[column] is not supported use df[!, column] instead.”

‘filename’ refers to the datafile I still want to import into a DataFrame called ‘Data’

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<div class="post-metadata">

**Author:** ![nilshg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nilshg/32/2283_2.png) [@nilshg](https://discourse.julialang.org/u/nilshg)\
**Post date:** [February 28, 2022, 4:46pm UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/24 "2022-02-28T16:46:28Z")

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Please make sure to enclose your code in triple backticks ````` to ensure it’s legible.

The error you are reporting cannot be caused by the lines of code you posted, as you are not indexing a DataFrame. This is how to get the error:

```julia
julia> df = DataFrame(rand(2, 2), :auto)
2×2 DataFrame
 Row │ x1 x2       
     │ Float64 Float64  
─────┼────────────────────
   1 │ 0.600275 0.241023
   2 │ 0.542208 0.758831

julia> df[:x1]
ERROR: ArgumentError: syntax df[column] is not supported use df[!, column] instead

```

which is not what you’re doing in your code. When I run your code I get:

```julia
julia> df_new = CSV("file.csv", DataFrame)
ERROR: MethodError: objects of type Module are not callable

```

from the third line of what you posted - you are doing `CSV()` which is trying to use `CSV` (the name of a module) as a function.

I think you have much more fundamental problems then how many columns you are reading in, your earlier posts in this thread about getting comments back from your code, and the error you just posted which is unconnected to your code suggest that you’re not really doing what you think you’re doing.

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<div class="post-metadata">

**Author:** ![jjdegruijter](https://avatars.discourse-cdn.com/v4/letter/j/fbc32d/32.png) [@jjdegruijter](https://discourse.julialang.org/u/jjdegruijter)\
**Post date:** [February 28, 2022, 7:57pm UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/25 "2022-02-28T19:57:48Z")

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Thank you Nils,  
The first three line of the code that I posted were suggested by somebody else of this forum. I do not understand what their purpose is. From what you say I understand it’s better to dselete them.

When I do that I get the message again that “syntax df[column] is not supported use df[!, column instead]”.  
Could that be caused by the next line in my code:

```julia
x = Data[:1]

```

I’ve been using this with julia-1.0

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<div class="post-metadata">

**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [February 28, 2022, 8:07pm UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/26 "2022-02-28T20:07:05Z")

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Yes. That is an expected error.

Someone above [mentioned](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/14) that this is an expected error already.

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<div class="post-metadata">

**Author:** ![jjdegruijter](https://avatars.discourse-cdn.com/v4/letter/j/fbc32d/32.png) [@jjdegruijter](https://discourse.julialang.org/u/jjdegruijter)\
**Post date:** [March 1, 2022, 4:19am UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/27 "2022-03-01T04:19:51Z")

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My code is now:

```julia
Data = CSV.read(filename, DataFrame; delim=',', header =false)
df = Data
x = df[!, 1]
y = df[!, 2]
# nr = df[!, 3] grid point identifier
z_pred = df[!, 4]
s2 = df[!, 5]
N = length(x)
println("Grid size : ", N)

```

And it WORKED. What a relief!  
I tghank you guys for all your patience and help.

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<div class="post-metadata">

**Author:** ![lawless-m](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lawless-m/32/30869_2.png) [@lawless-m](https://discourse.julialang.org/u/lawless-m)\
**Post date:** [March 1, 2022, 7:38am UTC](https://discourse.julialang.org/t/using-csv-read-to-import-data-from-a-data-input-file-into-a-dataframe/77120/28 "2022-03-01T07:38:57Z")

</div>

well done 🙂

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