# Readdlm, comments=true instead of false

**URL:** <https://discourse.julialang.org/t/readdlm-comments-true-instead-of-false/95810>\
**Category:** General Usage\
**Tags:** question\
**Created:** [March 9, 2023, 4:20pm UTC](https://discourse.julialang.org/t/readdlm-comments-true-instead-of-false/95810 "2023-03-09T16:20:36Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![marllos](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marllos/32/205917_2.png) [@marllos](https://discourse.julialang.org/u/marllos)\
**Post date:** [March 9, 2023, 4:20pm UTC](https://discourse.julialang.org/t/readdlm-comments-true-instead-of-false/95810/1 "2023-03-09T16:20:37Z")

</div>

Wouldn’t that be better? This would allow adding (commented) information to the end of a data file, without having to change the code.

---

<div class="post-metadata">

**Author:** ![Palli](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/palli/32/3380_2.png) [@Palli](https://discourse.julialang.org/u/Palli)\
**Post date:** [March 9, 2023, 4:52pm UTC](https://discourse.julialang.org/t/readdlm-comments-true-instead-of-false/95810/2 "2023-03-09T16:52:07Z")

</div>

Maybe, if other software did it that way, or this one from the start. It seems though that read.csv in R doesn’t use comments (since it’s faster, at least for them), nor does CSV.jl (that you likely should use; or Arrow.jl), though read.table defaults to supporting comments. I didn’t check the default in Pandas.

[https://stat.ethz.ch/R-manual/R-devel/library/utils/html/read.table.html](https://stat.ethz.ch/R-manual/R-devel/library/utils/html/read.table.html)

CSV files aren’t standardized, but it was tried, and that RFC does not officially support comments, likely why the default isn’t to skip them:

> **[RFC 4180: Common Format and MIME Type for Comma-Separated Values (CSV) Files](https://datatracker.ietf.org/doc/html/rfc4180)**
>
> This RFC documents the format used for Comma-Separated Values (CSV) files and registers the associated MIME type "text/csv". This memo provides information for the Internet community.

CSV is “awful”, “CSV++” is a proposal (or just use a proper standard like, Arrow):

> **[No Juice for You, CSV Format. It Just Makes You More Awful.](https://www.johnmyleswhite.com/notebook/2016/09/23/no-juice-for-you-csv-format-it-just-makes-you-more-awful/)**
>
> I just found a minimal example of how easy it is to confuse R’s CSV parser when providing it with ill-formatted data. To make it easy to understand, I put material for reproducing the problem up on GitHub.
> I’m sure one could construct many similar...

[https://csv.juliadata.org/stable/examples.html#comment\_example](https://csv.juliadata.org/stable/examples.html#comment_example)

---

<div class="post-metadata">

**Author:** ![marllos](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marllos/32/205917_2.png) [@marllos](https://discourse.julialang.org/u/marllos)\
**Post date:** [March 12, 2023, 1:57am UTC](https://discourse.julialang.org/t/readdlm-comments-true-instead-of-false/95810/3 "2023-03-12T01:57:04Z")

</div>

OK Palli, thank you.