Write an array to multi column CSV format using Ruby - ruby

Question

I have an array of arrays in Ruby that i'm trying to output to a CSV file (or text). That I can then easily transfer over to another XML file for graphing.
I can't seem to get the output (in text format) like so. Instead I get one line of data which is just a large array.
0,2
0,3
0,4
0,5
I originally tried something along the lines of this
File.open('02.3.gyro_trends.text' , 'w') { |file| trend_array.each { |x,y| file.puts(x,y)}}
And it outputs
0.2
46558
0
46560
0
....etc etc.
Can anyone point me in the "write" direction for getting either:
(i) .text file that can put my data like so.
trend_array[0][0], trend_array[0][1]
trend_array[1][0], trend_array[1][1]
trend_array[2][0], trend_array[2][1]
trend_array[3][0], trend_array[3][1]
(ii) .csv file that would put this data in separate columns.
edit I recently added more than two values into my array, check out my answer combining Cameck's solution.
This is currently what I have at the moment.
trend_array=[]
j=1
# cycle through array and find change in gyro data.
while j < gyro_array.length-2
if gyro_array[j+1][1] < 0.025 && gyro_array[j+1][1] > -0.025
trend_array << [0, gyro_array[j][0]]
j+=1
elsif gyro_array[j+1][1] > -0.025 # if the next value is increasing by x1.2 the value of the previous amount. Log it as +1
trend_array << [0.2, gyro_array[j][0]]
j+=1
elsif gyro_array[j+1][1] < 0.025 # if the next value is decreasing by x1.2 the value of the previous amount. Log it as -1
trend_array << [-0.2, gyro_array[j][0]]
j+=1
end
end
#for graphing and analysis purposes (wanted to print it all as a csv in two columns)
File.open('02.3test.gyro_trends.text' , 'w') { |file| trend_array.each { |x,y| file.puts(x,y)}}
File.open('02.3test.gyro_trends_count.text' , 'w') { |file| trend_array.each {|x,y| file.puts(y)}}
I know it's something really easy, but for some reason I'm missing it. Something with concatenation, but I found that if I try and concatenate a \\n in my last line of code, it doesn't output it to the file. It outputs it in my console the way I want it, but not when I write it to a file.
Thanks for taking the time to read this all.

Answer 1

File.open('02.3test.gyro_trends.text' , 'w') { |file| trend_array.each { |a| file.puts(a.join(","))}}

Answer 2

Alternately using the CSV Class:
def write_to_csv(row)
if csv_exists?
CSV.open(#csv_name, 'a+') { |csv| csv << row }
else
# create and add headers if doesn't exist already
CSV.open(#csv_name, 'wb') do |csv|
csv << CSV_HEADER
csv << row
end
end
end
def csv_exists?
#exists ||= File.file?(#csv_name)
end
Call write_to_csv with an array [col_1, col_2, col_3]

Answer 3

Thank you both #cameck & #tkupari, both answers were what I was looking for. Went with Cameck's answer in the end, because it "cut out" cutting and pasting text => xml. Here's what I did to get an array of arrays into their proper places.
require 'csv'
CSV_HEADER = [
"Apples",
"Oranges",
"Pears"
]
#csv_name = "Test_file.csv"
def write_to_csv(row)
if csv_exists?
CSV.open(#csv_name, 'a+') { |csv| csv << row }
else
# create and add headers if doesn't exist already
CSV.open(#csv_name, 'wb') do |csv|
csv << CSV_HEADER
csv << row
end
end
end
def csv_exists?
#exists ||= File.file?(#csv_name)
end
array = [ [1,2,3] , ['a','b','c'] , ['dog', 'cat' , 'poop'] ]
array.each { |row| write_to_csv(row) }