I have a nested array in ruby 2.4.4 that I need to flatten and send to a CSV.
A sample row of the data structure:
{:field1=>242,
:field2=>1950,
:field3=>"text",
:field4=>
{"sublevel1"=>{"detail1"=>"text", "detail2"=>24, "detail3"=>nil},
"sublevel2"=>{"anotherdetail"=>"text}}
The closest I've gotten is below but it doesn't unnest the deeper levels.
filename = "/home/myfile.csv"
headers = list.values[0].keys
data = list.values.map(&:values)
csvoutput = CSV.generate do |csv|
csv << headers
data.each do |single_row|
csv << single_row
end
end
File.write(filename, csv_output)
Thanks for your help
Is there a way to edit a CSV file using the map method in Ruby? I know I can open a file using:
CSV.open("file.csv", "a+")
and add content to it, but I have to edit some specific lines.
The foreach method is only useful to read a file (correct me if I'm wrong).
I checked the Ruby CSV documentation but I can't find any useful info.
My CSV file has less than 1500 lines so I don't mind reading all the lines.
Another answer using each.with_index():
rows_array = CSV.read('sample.csv')
desired_indices = [3, 4, 5].sort # these are rows you would like to modify
rows_array.each.with_index(desired_indices[0]) do |row, index|
if desired_indices.include?(index)
# modify over here
rows_array[index][target_column] = 'modification'
end
end
# now update the file
CSV.open('sample3.csv', 'wb') { |csv| rows_array.each{|row| csv << row}}
You can also use each_with_index {} insead of each.with_index {}
Is there a way to edit a CSV file using the map method in Ruby?
Yes:
rows = CSV.open('sample.csv')
rows_array = rows.to_a
or
rows_array = CSV.read('sample.csv')
desired_indices = [3, 4, 5] # these are rows you would like to modify
edited_rows = rows_array.each_with_index.map do |row, index|
if desired_indices.include?(index)
# simply return the row
# or modify over here
row[3] = 'shiva'
# store index in each edited rows to keep track of the rows
[index, row]
end
end.compact
# update the main row_array with updated data
edited_rows.each{|row| rows_array[row[0]] = row[1]}
# now update the file
CSV.open('sample2.csv', 'wb') { |csv| rows_array.each{|row| csv << row}}
This is little messier. Is not it? I suggest you to use each_with_index with out map to do this. See my another answer
Here is a little script I wrote as an example on how read CSV data, do something to data, and then write out the edited text to a new file:
read_write_csv.rb:
#!/usr/bin/env ruby
require 'csv'
src_dir = "/home/user/Desktop/csvfile/FL_insurance_sample.csv"
dst_dir = "/home/user/Desktop/csvfile/FL_insurance_sample_out.csv"
puts " Reading data from : #{src_dir}"
puts " Writing data to : #{dst_dir}"
#create a new file
csv_out = File.open(dst_dir, 'wb')
#read from existing file
CSV.foreach(src_dir , :headers => false) do |row|
#then you can do this
# newrow = row.each_with_index { |rowcontent , row_num| puts "# {rowcontent} #{row_num}" }
# OR array to hash .. just saying .. maybe hash of arrays..
#h = Hash[*row]
#csv_out << h
# OR use map
#newrow = row.map(&:capitalize)
#csv_out << h
#OR use each ... Add and end
#newrow.each do |k,v| puts "#{k} is #{v}"
#Lastly, write back the edited , regexed data ..etc to an out file.
#csv_out << newrow
end
# close the file
csv_out.close
The output file has the desired data:
USER#USER-SVE1411EGXB:~/Desktop/csvfile$ ls
FL_insurance_sample.csv FL_insurance_sample_out.csv read_write_csv.rb
The input file data looked like this:
policyID,statecode,county,eq_site_limit,hu_site_limit,fl_site_limit,fr_site_limit,tiv_2011,tiv_2012,eq_site_deductible,hu_site_deductible,fl_site_deductible,fr_site_deductible,point_latitude,point_longitude,line,construction,point_granularity
119736,FL,CLAY COUNTY,498960,498960,498960,498960,498960,792148.9,0,9979.2,0,0,30.102261,-81.711777,Residential,Masonry,1
448094,FL,CLAY COUNTY,1322376.3,1322376.3,1322376.3,1322376.3,1322376.3,1438163.57,0,0,0,0,30.063936,-81.707664,Residential,Masonry,3
206893,FL,CLAY COUNTY,190724.4,190724.4,190724.4,190724.4,190724.4,192476.78,0,0,0,0,30.089579,-81.700455,Residential,Wood,1
333743,FL,CLAY COUNTY,0,79520.76,0,0,79520.76,86854.48,0,0,0,0,30.063236,-81.707703,Residential,Wood,3
172534,FL,CLAY COUNTY,0,254281.5,0,254281.5,254281.5,246144.49,0,0,0,0,30.060614,-81.702675,Residential,Wood,1
I have the following Ruby code:
require 'octokit.rb'
require 'csv.rb'
CSV.foreach("actors.csv") do |row|
CSV.open("node_attributes.csv", "wb") do |csv|
csv << [Octokit.user "userid"]
end
end
I have a csv called actors.csv where every row has one entry - a string with a userid.
I want to go through all the rows, and for each row do Octokit.user "userid", and then store the output from each query on a separate row in a CSV - node_attributes.csv.
My code does not seem to do this? How can I modify it to make this work?
require 'csv'
DOC = 'actors.csv'
DOD = 'new_output.csv'
holder = CSV.read(DOC)
You can navigate it by calling
holder[0][0]
=> data in the array
holder[1][0]
=> moar data in array
make sense?
#make this a loop
profile = []
profile[0] = holder[0][0]
profile[1] = holder[1][0]
profile[2] = 'whatever it is you want to store in the new cell'
CSV.open(DOD, "a") do |data|
data << profile.map
end
#end the loop here
That last bit of code will print whatever you want into a new csv file
I am having trouble writing columns to a csv file with Ruby. Below is my snippet of code.
calc = numerator/denominator.to_f
data_out = "#{numerator}, #{denominator}, #{calc}"
File.open('cdhu3_X.csv','a+') do|hdr|
hdr << ["numerator","denominator","calculation\n"] #< column header
hdr << "#{data_out}\n"
end
The code adds the column headers to every line and I only need it at the top of each column of data. I have searched here and other places but can't find a clear answer to how its done.
Any help would be greatly appreciated.
I would recommend to use the CSV-library instead:
require 'csv'
CSV.open('test.csv','w',
:write_headers=> true,
:headers => ["numerator","denominator","calculation"] #< column header
) do|hdr|
1.upto(12){|numerator|
1.upto(12){ |denominator|
data_out = [numerator, denominator, numerator/denominator.to_f]
hdr << data_out
}
}
end
If you can't use the w option and you really need the a+ (e.g., the data isn't available all at once), then you could try the following trick:
require 'csv'
column_header = ["numerator","denominator","calculation"]
1.upto(12){|numerator|
1.upto(12){ |denominator|
CSV.open('test.csv','a+',
:write_headers=> true,
:headers => column_header
) do|hdr|
column_header = nil #No header after first insertion
data_out = [numerator, denominator, numerator/denominator.to_f]
hdr << data_out
end
}
}
The cleanest way to do this is to open the file once, in mode 'w', write the headers, and then write the data.
If there's some technical reason that can't do this (e.g., the data isn't available all at once), then you can use the IO#tell method on the file to return the current file position. When you open the file for appending, the position is set to the end of the file, so if the current file position is zero, then the file was newly created and has no headers:
File.open('cdhu3_X.csv', 'a+') do |hdr|
if hdr.tell() == 0 # file is empty, so write header
hdr << "numerator, denominator, calculation\n"
end
hdr << "#{data_out}\n"
end
Best way to handle csv file is to use Ruby's CSV module.
I had same problem after reading CSV code I came across this solution which i find most efficient.
headers = ['col1','col2','col3']
CSV.open(file_path, 'a+', {force_quotes: true}) do |csv|
csv << headers if csv.count.eql? 0 # csv.count method gives number of lines in file if zero insert headers
end
This works for me
headers = ["Reference Number", "Vendor Line Code"]
CSV.open(file_path, "wb") do |csv|
csv << headers
#vendor.vendor_items.each do |vi|
row_data = [vi.reference_number, vi.line_code]
csv << row_data
end
end
I'm trying to query a table, fetch all records, and save the result as a CSV file.
This is what I've done so far:
require 'OCI8'
conn = OCI8.new('scott','tiger','020')
file = File.open('output.csv','w') do |f|
conn.exec('select * from emp') do |e|
f.write log.join(',')
end
end
.. And while it does generate a CSV file, the problem is that all records get saved onto a single line. How can I put the data such that each record goes onto a new line ?
Well, you can use f.puts instead of f.write there, but I'd recommend you take a look at CSV module:
http://ruby-doc.org/stdlib/libdoc/csv/rdoc/index.html
outfile = File.open('csvout', 'wb')
CSV::Writer.generate(outfile) do |csv|
csv << ['c1', nil, '', '"', "\r\n", 'c2']
...
end
outfile.close
PS: Actually, there is another CSV library called FasterCSV, which became CSV in standard library in Ruby 1.9. But in general, any should be better than writing it yourself.