Ruby 之 csv 文件读写

csv 文件写入

require 'csv'
 
title = ["col1", "col2"]
contents = [["row11", "row12"], ["row21", "row22"]]
 
csv1 = CSV.open("test1.csv", "wb") do |csv|
  # write file title
  csv << title
 
  # write file body
  contents.each do |line|
    csv << line
  end
end
 
puts csv1.class
puts csv1.inspect
 
# UTF-8编码的文件，开头会加入BOM来表明编码方式
csv2 = CSV.generate("\xEF\xBB\xBF") do |csv|
    # write file title
    csv << title
 
    # write file body
    contents.each do |line|
      csv << line
    end
end
File.open("test2.csv", "wb"){|f| f << csv2}
 
puts csv2.class
puts csv2.inspect

Array
[["row11", "row12"], ["row21", "row22"]]
String
"col1,col2\nrow11,row12\nrow21,row22\n"

csv 文件读取

test.csv

col1,col2
row11,row12
row21,row22

按行读取 

require 'csv'
 
csv3 = []
CSV.open("test1.csv") do |csv|
  csv.each do |line|
    csv3 << line
  end
end
 
puts csv3.class
puts csv3.inspect
 
csv4 = []
File.open("test2.csv", "rb") do |f|
  f.each do |line|
    csv4 << line
  end
end
puts csv4.class
puts csv4.inspect

Array
[["col1", "col2"], ["row11", "row12"], ["row21", "row22"]]
Array
["\xEF\xBB\xBFcol1,col2\n", "row11,row12\n", "row21,row22\n"]

以键值对形式读取

require 'csv'
 
rows = CSV.read("test.csv", headers:true)
title = rows.headers
contents = []
rows.each do |row|
  contents << row.to_h
end
puts title.inspect
puts contents.inspect
 
puts
rows = CSV.parse("col1,col2\nrow11,row12\nrow21,row22", headers:true)
title = rows.headers
contents = []
rows.each do |row|
  contents << row.to_h
end
puts title.inspect
puts contents.inspect

["col1", "col2"]
[{"col1"=>"row11", "col2"=>"row12"}, {"col1"=>"row21", "col2"=>"row22"}]
 
["col1", "col2"]
[{"col1"=>"row11", "col2"=>"row12"}, {"col1"=>"row21", "col2"=>"row22"}]