问题
I have a rake file that pulls in data from an external CSV file and enumerates through it with:
CSV.foreach(file, :headers => true) do |row|
What is the most effective way (in ruby) to specify the starting point within the spreadsheet?
:headers => true allows me to start importing from the second line, but what if I want to start a line 20?
回答1:
Use .drop(#rows to ignore):
CSV.open(file, :headers => true).drop(20).each do |row|
回答2:
Ruby enumerators include a drop method that will skip over the first n items.
When not passed a block, CSV.foreach returns an enumerator.
You can use
CSV.foreach(file, :headers => true).drop(20).each do |row|
This will skip the first 20 data rows (the header row does NOT count as one of those twenty).
来源：https://stackoverflow.com/questions/22898317/specify-starting-point-of-foreach-enumerator-in-ruby