I like to export a dataset from my rails application as a csv file using the builtin csv library of rails. Usually a csv file is written row wise like in my example below which comes from my datasets_controller.rb:
require 'csv'
dataset = Dataset.find(6)
dataset_headers = dataset.datacolumns.collect { |dc| dc.columnheader }
csv_file = CSV.generate do |csv|
csv << dataset_headers
end
And now my question is if I could also write my csv files column wise like this?
require 'csv'
dataset_columns = Datacolumn.all(:conditions => ["dataset_id = ?", 6], :order => "columnnr ASC").uniq
csv_file = CSV.generate do |csv|
csv << "here put one after another all my data columns"
end
EDIT:
Based on Douglas suggestion I came up with the colde below.
data_columns=Datacolumn.all(:conditions => ["dataset_id = ?", dataset.id], :order => "columnnr ASC").uniq
CSV.generate do |csv|
value=Array.new
data_columns.each do |dc|
value << dc.columnheader
dc.sheetcells.each do |sc|
if sc.datatype && sc.datatype.is_category? && sc.category
value << sc.category.short
elsif sc.datatype && sc.datatype.name.match(/^date/) && sc.accepted_value
value << sc.accepted_value.to_date.to_s
elsif sc.accepted_value
value << sc.accepted_value
else
value << sc.import_value
end
end
csv << value
value = Array.new
end
end
The output is not transposed for this case and looks like this:
height,10,2,<1,na
fullauthor,Fortune,(Siebold & Zucc.) Kuntze,Fortune,(Siebold & Zucc.) Kuntze
Year,1850,1891,1850,1891
fullname,Mahonia bealei,Toxicodendron sylvestre,Mahonia bealei,Toxicodendron sylvestre
But when I change the line which writes the csv to
csv << value.transpose
I get an error which tells me that it could not convert a string to array to do that.
Anybody an Idea how to fix this?
Any help with this would be appreciated.
Best Claas
You could use Array#transpose, which will flip your rows to columns. A simple example:
> a = [['name', 'charles', 'dave'],['age', 24, 36],['height', 165, 193]]
=> [["name", "charles", "dave"], ["age", 24, 36], ["height", 165, 193]]
> a.transpose
=> [["name", "age", "height"], ["charles", 24, 165], ["dave", 36, 193]]
Thus, assuming dataset_columns is an array:
require 'csv'
dataset_columns = Datacolumn.all(:conditions => ["dataset_id = ?", 6], :order => "columnnr ASC").uniq
csv_file = CSV.generate do |csv|
csv << dataset_columns.transpose
end
Related
I have 1 field delivery_time It is in an array
include :
DELIVERY_TIME = [
I18n.t("activerecord.attributes.order.none_delivery_time"),
"09:00～12:00",
"12:00～14:00",
"14:00～16:00",
"16:00～18:00",
"18:00～20:00",
"19:00～21:00",
"20:00～21:00",
].freeze
when I downloaded the csv directory it was in the form
"09:00～12:00"
but i want now when I download it will take the form :
"0912"
how to customize it?
my code:
def perform
CSV.generate(headers: true) do |csv|
csv << attributes
orders.each do |order|
csv << create_row(order)
end
end
end
def create_row(order)
row << order.delivery_time
end
AFAIU, you need to modify DELIVERY_TIME to fit your format. CSV is absolutely out of scope here. So to transform values, one should split by ～ and take the hour from the result.
DELIVERY_TIME = [
"09:00～12:00",
"12:00～14:00",
"14:00～16:00",
"16:00～18:00",
"18:00～20:00",
"19:00～21:00",
"20:00～21:00",
].freeze
DELIVERY_TIME.map { |s| s.split('～').map { |s| s[0...2] }.join }
#⇒ ["0912", "1214", "1416", "1618", "1820", "1921", "2021"]
A safer method would be to use DateTime#parse for this
require 'time'
DELIVERY_TIME.map do |s|
s.split('～').map { |s| DateTime.parse(s).strftime("%H") }.join
end
#⇒ ["0912", "1214", "1416", "1618", "1820", "1921", "2021"]
It's not real clear what you're asking, but I'd probably start with something like this:
"09:00～12:00".scan(/\d{2}/).values_at(0, 2).join # => "0912"
Using that in some code:
"09:00～12:00".scan(/\d{2}/).values_at(0, 2).join # => "0912"
DELIVERY_TIME = [
'blah',
"09:00～12:00",
"12:00～14:00",
"14:00～16:00",
"16:00～18:00",
"18:00～20:00",
"19:00～21:00",
"20:00～21:00",
].freeze
ary = [] << DELIVERY_TIME.first
ary += DELIVERY_TIME[1..-1].map { |i|
i.scan(/\d{2}/).values_at(0, 2).join
}
# => ["blah", "0912", "1214", "1416", "1618", "1820", "1921", "2021"]
I'm attempting to copy all the contents of a CSV file over to an excel workbook using the AXLSX gem. On a second sheet, I only want 2 of the columns copied over. Below is an example.
I tried the '.map' method but that didn't work.
require 'csv'
require 'Axlsx'
p = Axlsx::Package.new
wb = p.workbook
animals = CSV.read('test.csv', headers:true)
column = ['Animals', 'Name']
headers = Array.new
headers << "Animal"
headers << "Name"
headers << "Age"
headers << "State"
wb.add_worksheet(:name => 'Copy') do |sheet|
animals.each do |row|
headers.map { |col| sheet.add_row [row[col]] }
end
end
wb.add_worksheet(:name => 'Names') do |sheet|
animals.each do |row|
column.map { |col| sheet.add_row [row[col]] }
end
end
p.serialize 'Animals.xlsx'
CSV - But also desired output on XLSX
Output from my code
At first read file using IO::readlines, then split every line (separate by the cells using Array#map and String#split).
It will produce nested array. Something like
[["Animal", "Name", "Age", "State"], ["Dog", "Rufus", "7", "CA"], ["Bird", "Magnus", "3", "FL"]]
Each subarray here is the row of your table, each item of subarray is the cell of your table.
If you need just "Name" column on second sheet you need make nested array
[["Name"], ["Rufus"], ["Magnus"]]
That's all you need to generate XLSX file.
For example you have animals.csv with data serapated by , and want to generate animals.xlsx:
require 'axlsx'
copy = File.readlines('animals.csv', chomp: true).map { |s| s.split(',') }
names = copy.map { |l| [l[1]] }
Axlsx::Package.new do |p|
p.workbook.add_worksheet(name: 'Animals') { |sheet| copy.each { |line| sheet.add_row(line) }}
p.workbook.add_worksheet(name: 'Names') { |sheet| names.each { |line| sheet.add_row(line) }}
p.serialize('animals.xlsx')
end
I want to add new column and update existing values in CSV response. How can I do simpler and better way of doing the below transformations?
Input
id,name,country
1,John,US
2,Jack,UK
3,Sam,UK
I am using following method to parse the csv string and add new column
# Parse original CSV
rows = CSV.parse(csv_string, headers: true).collect do |row|
hash = row.to_hash
# Merge additional data as a hash.
hash.merge('email' => 'sample#gmail.com')
end
# Extract column names from first row of data
column_names = rows.first.keys
# Generate CSV after transformation of csv
csv_response = CSV.generate do |csv|
csv << column_names
rows.each do |row|
# Extract values for row of data
csv << row.values_at(*column_names)
end
end
I am using following method to parse the csv and update existing values
name_hash = {"John" => "Johnny", "Jack" => "Jackie"}
Parse original CSV
rows = CSV.parse(csv_string, headers: true).collect do |row|
hash = row.to_hash
hash['name'] = name_hash[hash['name']] if name_hash[hash['name']] != nil
hash
end
# Extract column names from first row of data
column_names = rows.first.keys
# Generate CSV after transformation of csv
csv_response = CSV.generate do |csv|
csv << column_names
rows.each do |row|
# Extract values for row of data
csv << row.values_at(*column_names)
end
end
One possible option given the following reference data to be used for modifying the table:
name_hash = {"John" => "Johnny", "Jack" => "Jackie"}
sample_email = {'email' => 'sample#gmail.com'}
Just store in rows the table converted to hash:
rows = CSV.parse(csv_string, headers: true).map(&:to_h)
#=> [{"id"=>"1", "name"=>"John", "country"=>"US"}, {"id"=>"2", "name"=>"Jack", "country"=>"UK"}, {"id"=>"3", "name"=>"Sam", "country"=>"UK"}]
Then modify the hash based on reference data (I used Object#then for Ruby 2.6.1 alias of Object#yield_self for Ruby 2.5):
rows.each { |h| h.merge!(sample_email).then {|h| h['name'] = name_hash[h['name']] if name_hash[h['name']] } }
#=> [{"id"=>"1", "name"=>"Johnny", "country"=>"US", "email"=>"sample#gmail.com"}, {"id"=>"2", "name"=>"Jackie", "country"=>"UK", "email"=>"sample#gmail.com"}, {"id"=>"3", "name"=>"Sam", "country"=>"UK", "email"=>"sample#gmail.com"}]
Finally restore the table:
csv_response = CSV.generate(headers: rows.first.keys) { |csv| rows.map(&:values).each { |v| csv << v } }
So you now have:
puts csv_response
# id,name,country,email
# 1,Johnny,US,sample#gmail.com
# 2,Jackie,UK,sample#gmail.com
# 3,Sam,UK,sample#gmail.com
i want to export csv in 3 columns with the type of it but the result that i get is not the same what i want. it's just only one column to show all my data, please help me what should i do
require 'nokogiri'
require 'csv'
page = Nokogiri::HTML(open("index.html"))
fullName = page.css('li._5i_q').css("a[data-gt]").children.map {|name| name.text }
shortURL = page.css('li._5i_q').css("._5j0e a[data-hovercard]")
myID = shortURL.map {|element|
element["data-hovercard"][/id=([^&]*)/].gsub('id=', '')
}
messenger = shortURL.map {|element|
element["data-hovercard"][/id=([^&]*)/].gsub('id=', '') + "#gmail.com"
}
attributes = %w{ID FullName Messenger}
CSV.open('chatId.csv', 'w') do |csv|
csv << attributes
myID.each do |x|
csv << [x]
end
fullName.each do |y|
csv << [y]
end
messenger.each do |z|
csv << [z]
end
end
It's all my code
You will have to write row by row when exporting data to csv. Therefore, try to create an array of [x, y, z] and export them using to_csv method. For example:
data = myID.zip(fullName, shortUrl)
CSV.open('chatId.csv', 'w') do |csv|
csv << attributes
csv << "\n"
data.each do |d|
csv << d.to_csv
end
end
the following code:
[1,3,5].to_csv
=> "1,3,5\n" # this is good
[[1,3,5], [2,4,6]].to_csv
=> "135,246\n" # why doesn't it just do it for array of array?
but require this instead:
data = [[1,3,5], [2,4,6]]
csv_string = FasterCSV.generate do |csv|
data.each {|a| csv << a}
end
=> "1,3,5\n2,4,6\n"
or shorter:
data = [[1,3,5], [2,4,6]]
csv_string = FasterCSV.generate {|csv| data.each {|a| csv << a}}
=> "1,3,5\n2,4,6\n"
The question is, when given an array of array, why is to_csv not designed to handle it automatically, so that in Rails, we can do
respond_to do |format|
format.csv { render :text => data.to_csv }
[[1,3,5], [2,4,6]].each{ |line| puts line.to_csv } isn't so bad. You could always override Array#to_csv if you wanted.
I suspect FasterCSV's decision to not implement that was because it is hard to be absolutely certain that's what the programmer will want. What if the input happens to be
[[1], 2, 3, 4] ? Just looking at the first element of the outer array would make you think that it may be an array of arrays...