[m-users.] Read csv file with variable number and type of fields

Julien Fischer jfischer at opturion.com
Thu Sep 3 11:01:42 AEST 2015


On Wed, 2 Sep 2015, Dirk Ziegemeyer wrote:

>> Am 02.09.2015 um 06:44 schrieb Julien Fischer <jfischer at opturion.com>:
>> Yes, but there's nothing that prevents you from reading in the header
>> line, setting up the record structure base on that and then
>> initializing a new CSV reader based on that.
>>> My idea is to read the file in two steps:
>>> 1. the header line (in order to determine number and type of fields), e.g. with some DCG rules or module parsing_utils
>>> 2. the rest
>>> Is this a valid approach and can I combine io.read_line_as_string/3 to
>>> read the header line and stream.get/4 to read the rest of the file?
>> Yes, it would work.  It's going to be a bit fiddly as you are going to
>> have to handle things like quoted header names etc yourself.  A better
>> approach would be to use the CSV library's raw_reader to read in just
>> the header line, set up the record structure based on that, and then
>> intialize a new reader to handle the rest of the data.
>> I've attached a small example of how this could be done.
> Thank you for this very complete example. The combination of
> raw_reader and the „normal“ csv reader is exactly what I’m looking
> for.

If such functionality is useful, I could add it to the CSV library.


More information about the users mailing list