Take the 2-minute tour ×
Programmers Stack Exchange is a question and answer site for professional programmers interested in conceptual questions about software development. It's 100% free, no registration required.

A lot of my work is done with .csv extracts (reports) from databases. As I have been programming in Clojure, I've received comments that relying on vector indexes creates dependencies. I understand why, and concur.

I am rewriting one of my programs to take advantage of the fact that each report's first row contain the column headings, and I could go after each row of data I want by map key. I am rewriting some code to zipmap the headings made into map keys and one row of data (at a time) so I can access the data I want. Here is an example.

(def bene-csv-inp  (fetch-csv-data "benetrak_roster.csv"))
(def bene-csv-cols (first bene-csv-inp))
(def bene-csv-data (rest bene-csv-inp))
(def zm1 (zipmap 
     (map #(keyword %1) bene-csv-cols) 
                        (first bene-csv-data)))
(zm1 :EmploymentStartDate)

Does a higher level of extraction exist, and if so, what is it that would allow my code not to have to have to hard-code :EmploymentStartDate ? If my code has to know these keys, then how is that also not a dependency like an index?

Personally, I like going after the data with map keys, because it's less confusing and more informative than indexes. However, I believe I still have a dependency.


share|improve this question

1 Answer 1

up vote 2 down vote accepted

Well, you're no longer dependent on the order of the columns in the data, but you're now dependent on the column names. If someone adds a column to an extract, even if it's in the middle, you're better off, because your code won't break. If someone deletes or renames a column, you'll still have an issue. If it's more likely that someone will rename a column than delete or move it, you'd be better off sticking with indexes. I do agree that it's usually easier to understand code that refers to (hopefully) meaningful names than raw column numbers. It should make debugging easier too, since if a column is missing you can report "No such column named 'EmploymentStartDate'" rather than "Missing column: 23".

share|improve this answer
Thanks. It is well worth re-writing my small program, because the indexes were beginning to confuse me, and I wrote the code. So, that's a bad sign. If the report blows up due to a column rename, I can deal with that. Again, thanks. –  octopusgrabbus Aug 7 '12 at 19:43

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.