Generate CSV from Ruby results - ruby

I currently have this script that generates usernames from a given CSV. Rather than printing these results to the console, how can I write a new CSV with these results?
This is the script I currently have, runs with no errors. I am assuming if I write a new CSV in the do |row| block it is going to create x amount of new files which I do not want.
require 'csv'
CSV.foreach('data.csv', :headers => true) do |row|
id = row['id']
fn = row['first_name']
ln = row['last_name']
p fn[0] + ln + id[3,8]
end

Just manage the CSV file to write around the reading:
CSV.open("path/to/file.csv", "wb") do |csv|
CSV.foreach('data.csv', :headers => true) do |row|
id = row['id']
fn = row['first_name']
ln = row['last_name']
csv << [fn[0], ln, id[3,8]]
# or, to output it as a single column:
# csv << ["#{fn[0]}#{ln}#{id[3,8]}"]
end
end
Writing CSV to a file.

Related

Ruby CSV - Write on same row without overwriting?

I'm using
CSV.open(filename, "w") do |csv|
to create and write to a csv file in one ruby.rb file and now I need to open it and edit it in a second .rb file. Right now I'm using CSV.open(filename, "a") do |csv| but that creates new rows rather than adding the new content to the end of the existing rows.
If I use CSV.open(filename, "w") do |csv| the second time it overwrites the first rows.
edit:
# Create export CSV
final_export_csv = "filepath_final.csv"
# Create filename for CSV file
imported_csv_filename = "imported_file.csv"
CSV.open(final_export_csv, "w", headers: ["several", "headers"] + [:new_header], write_headers: true) do |final_csv|
# Read existing CSV file
CSV.foreach(imported_csv_filename) do |old_csv_row|
# Read a row, add the new column, write it to the new row
CSV.open(denominator_csv_filename, "r+") do |new_csv_col|
# gathering some data code
data = { passed.in }
# Write data
new_csv_col <<
[
passedin[:data]
]
old_csv_row[:new_header] = passedin[:data]
final_export_csv << old_csv_row
end
end
end
end
end
As tadman comments, you can't actually edit a file in place. Well, you can but all the lines have to remain the same length. You're not doing that.
Instead, read a row, modify it, and write it to a new CSV. Then replace the old file with the new one. Be careful to avoid slurping the entire CSV into memory, CSV files can get quite large.
require 'csv'
require 'tempfile'
require 'fileutils'
csv_file = "test.csv"
# Write the new file to a tempfile to avoid polluting the directory.
temp = Tempfile.new
# Read the header line.
old_csv = CSV.open(csv_file, "r", headers: true, return_headers: true)
old_csv.readline
# Open the new CSV with the existing headers plus a new one.
new_csv = CSV.open(
temp, "w",
headers: old_csv.headers + [:new],
write_headers: true
)
# Read a row, add the new column, write it to the new CSV.
old_csv.each do |row|
row[:new] = 42
new_csv << row
end
old_csv.close
new_csv.close
# Replace the old CSV with the new one.
FileUtils.move(temp.path, csv_file)

How do I access the filename of the CSV file I just opened?

I have a method that looks like this:
def extract_websites
websites = []
csvs = Dir["#{#dir_name}/#{#state}/*.csv"]
csvs.each do |csv|
CSV.foreach(csv, headers: true) do |row|
websites << row['Website']
end
end
websites.uniq!
end
But what I need want to do is for each CSV file that is opened, I would like to detect the name of that file.
How do I do that?
In your sample the variable csv holds the path of the CSV file.
That local variable is available in the blocks of its children, it shares its scope down but not upwards.
So:
def extract_websites
websites = []
csvs = Dir["#{#dir_name}/#{#state}/*.csv"]
csvs.each do |csv|
puts File.expand_path(csv) # show the full path for each csv file
CSV.foreach(csv, headers: true) do |row|
puts csv # shows unexpanded path for each row of a csv
websites << row['Website']
end
end
websites.uniq!
end
should print out the path for each CSV file and for each row.

How to map and edit a CSV file with Ruby

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

Trouble writing to a workbook using ruby spreadsheet gem from CSV file

I am currently new to Ruby and am having a hard time writing to an excel file.
I want to parse through a CSV file, extract data where the 'food' column in the csv file = butter and put the rows where 'food' column = butter into a new excel workbook. I can write the data that contains butter in the 'food' column just fine into a CSV file but am having trouble writing it to a workbook (excel format).
require 'rubygems'
require 'csv'
require 'spreadsheet'
csv_fname = 'commissions.csv'
options = { headers: :first_row }
food_type = { 'food' => 'butter'}
food_type_match = nil
CSV.open(csv_fname, 'r', options) do |csv|
food_type_match = csv.find_all do |row|
Hash[row].select { |k,v| food_type[k] } == food_type
end
end
#writing the 'butter' data to a CSV file
#CSV.open('butter.csv', 'w') do |csv_object|
# food_type_match.each do |row_array|
# csv_object << row_array
# end
#end
book = Spreadsheet::Workbook.new
sheet1 = book.create_worksheet
food_type_match.each do |csv|
csv.each_with_index do |row, i|
sheet1.row(i).replace(row)
end
end
The spreadsheet generates but comes out blank. I have searched through numerous topics on ruby spreadsheet but I cannot get it to work. Any help would be greatly appreciated.
Updated Completely
What if you try this:
book = Spreadsheet::Workbook.new
sheet1 = book.create_worksheet
food_type_match.each do |csv|
csv.each_with_index do |row, i|
sheet1.insert_row(i,row)
end
end
book.write('/path_to_output_location/book.xls')
Also where does this output to? I cannot see a give path for this so I would think that is the issue but you say it generates? I added the write line because the code states this for #write
Write this Workbook to a File, IO Stream or Writer Object. The latter will
make more sense once there are more than just an Excel-Writer available.
Like I said I am completely unfamiliar with this gem and the documentation is terrible with axslx it would be something like this
package = Axlsx::Package.new
book = package.workbook
book.add_worksheet do |sheet|
food_type_match.each do |csv|
sheet.add_row csv
end
end
package.serialize('/path_to_output_location/book.xlsx')
Try write_xlsx gem. Here is my simple csvtoxlsx.rb script to combine *.csv in a folder to a single.xlsx:
require "csv"
require "write_xlsx"
def csvtoxls(csv, xlsx)
count = 0
workbook = WriteXLSX.new(xlsx)
Dir[csv].sort.each do | file |
puts file
name = File.basename(file, ".csv")
worksheet = workbook.add_worksheet(name)
i = 0
CSV.foreach(file) do | row |
worksheet.write_row(i, 0, row)
i = i + 1
count = count + 1
end
end
workbook.close
count
end
abort("Syntax: ruby -W0 csvtoxlsx.rb 'folder/*.csv' single.xlsx") if ARGV.length < 2
time_begin = Time.now
count = csvtoxls(ARGV[0], ARGV[1])
time_spent = Time.now - time_begin
puts "csvtoxlsx process #{ARGV[0]} with #{count} rows in #{time_spent.round(2)} seconds"

Reading every line in a CSV and using it to query an API

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

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