# New String7 type from result of CSV.file|\>DataFrame makes my function failing (which takes a String as input)
**URL:** https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985
**Category:** General Usage
**Tags:** dataframes, csv
**Created:** [September 30, 2021, 10:01am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985 "2021-09-30T10:01:54Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@jdad](https://discourse.julialang.org/u/jdad)
#### Post date: [September 30, 2021, 10:01am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/1 "2021-09-30T10:01:55Z")
My script used to work till yesterday, but is now failing because of the following error
```julia
ERROR: LoadError: MethodError: no method matching get_symbols_ta(::String7, ::String, ::String)
Closest candidates are:
get_symbols_ta(::String, ::String, ::String) at C:\cygwin64\home\davidj\pb\anto-port\src\Yfjd.jl:190
Stacktrace:
[1] get_adj(tick::String7, ddeb::String, dfin::String)
@ Main C:\cygwin64\home\davidj\pb\anto-port\src\functions_gets.jl:9
[2] getit(tick::String7, ddeb::String, dfin::String)
@ Main C:\cygwin64\home\davidj\pb\anto-port\src\functions_gets.jl:14
[3] get_tatous(aitick::Vector{String7})
@ Main C:\cygwin64\home\davidj\pb\anto-port\src\functions_gets.jl:54
[4] get_tatous3(aitick::Vector{String7}, ainb::Vector{Int64})
@ Main C:\cygwin64\home\davidj\pb\anto-port\src\functions_gets.jl:82
[5] macro expansion
@ C:\cygwin64\home\davidj\pb\anto-port\src\tactantoh.jl:98 [inlined]
[6] macro expansion
@ C:\Users\davidj\.julia\packages\TimerOutputs\SSeq1\src\TimerOutput.jl:236 [inlined]
[7] macro expansion
@ C:\cygwin64\home\davidj\pb\anto-port\src\tactantoh.jl:96 [inlined]
[8] top-level scope
@ C:\Users\davidj\.julia\packages\TimerOutputs\SSeq1\src\TimerOutput.jl:236
in expression starting at C:\cygwin64\home\davidj\pb\anto-port\src\tactantoh.jl:6
```
I traced this to the appearance of `String7` (unrecognized by my `get_symbol_ta function`) to the following
```julia
dfaitxt="""
Tick Actions Coursi Nombre Domaine InCac40
TTE.PA Total 36.32 36 Energie Y
DG.PA Vinci 77.57 13 construction Y
NK.PA Imerys 35.92 29 Meteaux/TerresRares N
PUB.PA Publicis 28.99 33 Communication/Publicité Y
SGO.PA SaintGobain 28.65 17 Travaux Y
EN.PA Bouygues 30.71 16 Telecomms/Construction N
BN.PA Danone 58.56 8 Alimentaire Y
ADP.PA ADP 92.82 5 Aeroports N
SK.PA SEB 143.59 3 Electromenager N
CS.PA AXA 21.45 15 Assurances Y
SOI.PA SOITEC 166.72 2 Technologie/Semiconducteurs N
KORI.PA Korian 30.90 16 Sante N
ENGI.PA ENGIE 12.22 41 Energie Y
"""
julia> dfai=CSV.File(IOBuffer(dfaitxt),delim=" ",ignorerepeated=true) |> DataFrame
13×6 DataFrame
Row │ Tick Actions Coursi Nombre Domaine InCac40
│ String7 String15 Float64 Int64 String31 String1
─────┼─────────────────────────────────────────────────────────────────────────────
1 │ TTE.PA Total 36.32 36 Energie Y
2 │ DG.PA Vinci 77.57 13 construction Y
3 │ NK.PA Imerys 35.92 29 Meteaux/TerresRares N
4 │ PUB.PA Publicis 28.99 33 Communication/Publicité Y
5 │ SGO.PA SaintGobain 28.65 17 Travaux Y
6 │ EN.PA Bouygues 30.71 16 Telecomms/Construction N
7 │ BN.PA Danone 58.56 8 Alimentaire Y
8 │ ADP.PA ADP 92.82 5 Aeroports N
9 │ SK.PA SEB 143.59 3 Electromenager N
10 │ CS.PA AXA 21.45 15 Assurances Y
11 │ SOI.PA SOITEC 166.72 2 Technologie/Semiconducteurs N
12 │ KORI.PA Korian 30.9 16 Sante N
13 │ ENGI.PA ENGIE 12.22 41 Energie Y
julia>
```
So, question : how to make things work again ? Should I convert `Tick` to `String` ? Or is there a way that `get_symbols_ta` can accept a `String7` ?
For information, CSV version is 0.9.4 and DataFrames one is 1.2.2. Functions worked with versions CSV#0.8.5 and DataFrames#1.2.0
Thank you for any help and suggestions.
---
### Author:  [@oheil](https://discourse.julialang.org/u/oheil)
#### Post date: [September 30, 2021, 10:30am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/2 "2021-09-30T10:30:19Z")
[https://csv.juliadata.org/stable/reading.html#stringtype](https://csv.juliadata.org/stable/reading.html#stringtype)
try
```julia
stringtype=String
```
---
### Author:  [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)
#### Post date: [September 30, 2021, 10:55am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/3 "2021-09-30T10:55:56Z")
You should write your code to accept `::AbstractString` instead of `String`. That will get rid of this particular method error and you get to take advantage of the performance of `String7`.
---
### Author:  [@Palli](https://discourse.julialang.org/u/Palli)
#### Post date: [September 30, 2021, 11:05am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/4 "2021-09-30T11:05:10Z")
String7 etc. is meant for optimization, and as I suspected it would break a lot of code that accepts String only. That code needs to accept AbstractString instead, what most code should actually use in function definitions, if defining a type at all. That’s been true for a while, even though you’ve gotten away without that, since String isn’t the only type, there are others in packages, but I guess not yet widely used. CSV.jl is however widely used, I suspect the first widely used package to define its own string types.
That’s my theory anyway. A workaround is to convert to String (or ask for it in the first place) and then call functions that only assume those. I have my own idea, no code yet, how to change string handling in Julia similar to String7, while keeping the API the same, all hidden behind String, and I would prefer for only one good default String type in base, so that others aren’t needed.
---
### Author:  [@dmolina](https://discourse.julialang.org/u/dmolina)
#### Post date: [September 30, 2021, 3:04pm UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/5 "2021-09-30T15:04:20Z")
Thank you for the question and thanks, @pdeffebach for the solution. Actually, a few days ago I have a problem with that using MLJ (and DecisionTree), because they were different String type. Changing all types from the DataFrame to String has solved all my problems.
---
### Author:  [@jdad](https://discourse.julialang.org/u/jdad)
#### Post date: [October 1, 2021, 7:50am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/6 "2021-10-01T07:50:41Z")
Dear @oheil, thank you, this is a good “quick-and-dirty” fix that neeeds only to fix the CSV call, so easier. I tried it and it works fine, thank you very much!
---
### Author:  [@jdad](https://discourse.julialang.org/u/jdad)
#### Post date: [October 1, 2021, 7:53am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/7 "2021-10-01T07:53:49Z")
Dear @pdeffebach, thank you, it works and as you said I get much better performance with string handling; only inconvenient - is that really one?- is that I had to modify my library module.
So I mark your proposal as the solution as performance is better.
---
### Author:  [@jdad](https://discourse.julialang.org/u/jdad)
#### Post date: [October 1, 2021, 8:00am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/8 "2021-10-01T08:00:28Z")
Dear @Palli, thank you fotr your insightful remarks. When you will have code (or at least implementation outline) for your “new but identical” String API I would be interested to see it / understand it. Question, when you say others String typer not needed in Base, you mean you would propose replace the current implementatrion by you new one ?
Aside, I saw that `String7` etc. are defined in both `WeakRefStrings` and the brand new `InlineStrings` Is this new module an intended fork (in fact a split?) of WeakRefsStrings ? Or is there another reason for the fork or separation?
---
### Author:  [@Palli](https://discourse.julialang.org/u/Palli)
#### Post date: [October 1, 2021, 11:09pm UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/9 "2021-10-01T23:09:51Z")
Just answering here, immediate issue is resolved so this is kind of off-topic:
What you could do, and I believe there’s even a Julia issue on it, is have a hybrid of the inline string and a regular `String`. I.e.
```julia
struct HybridString
prefix::String7 # would prefer String8 type, would also fit in a register and saving length not needed
full_string::String # possibly type Ptr{String}
end
```
Often your prefix is the whole string and the other full\_string can be a null pointer, not stressing the garbage collector. Then it would take as much memory as String15/16 so that’s the tradeoff. If you know strings are never longer than String7 then those are still a good idea. Many strings in your String31 column could fit in my type of string, but for your dataframe all the strings in that column are padded to 31 bytes. Most strings are short, but long strings do not have to be fully inline.
Then I have an idea to have 24 letters in the 8-byte prefix, but even without that the prefix should give you fast sorting already. My idea would give localized sorting for e.g. Icelandic alphabet, English and more languages, and O(1) indexing in most cases.
---
### Author:  [@jdad](https://discourse.julialang.org/u/jdad)
#### Post date: [October 2, 2021, 6:58am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/10 "2021-10-02T06:58:45Z")
Very interesting ! Thank you for sharing your views, please continue the very good work.
---
### Author:  [@wjulia](https://discourse.julialang.org/u/wjulia)
#### Post date: [June 7, 2025, 7:13am UTC](https://discourse.julialang.org/t/new-string7-type-from-result-of-csv-file-dataframe-makes-my-function-failing-which-takes-a-string-as-input/68985/11 "2025-06-07T07:13:37Z")
Here my a tricky.
The following command of
convert.(String,dfai[:,:dfai])
to the type of String.
Wow, just for funny.