I've been trying to work with getting a single column out of a csv file.
I've gone through the documentation, http://www.ruby-doc.org/stdlib/libdoc/csv/rdoc/index.html
but still don't really understand how to use it.
If I use CSV.table
, the response is incredibly slow compared to CSV.read
. I admit the dataset I'm loading is quite large, which is exactly the reason I only want to get a single column from it.
My request is simply currently looks like this
@dataTable = CSV.table('path_to_csv.csv')
and when I debug I get a response of
#<CSV::Table mode:col_or_row row_count:2104 >
The documentation says I should be able to use by_col(), but when I try to output
<%= debug @dataTable.by_col('col_name or index') %>
It gives me "undefined method 'col' error"
Can somebody explain to me how I'm supposed to use CSV? and if there is a way to get columns faster using 'read' instead of 'table'?
I'm using Ruby 1.92, which says that it is using fasterCSV, so I don't need to use the FasterCSV gem.
Best Answer
To pluck a column out of a csv I'd probably do something like the following:
That should be substantially faster than any operations on CSV.Table