How do I make an array of arrays out of a CSV? - ruby

I have a CSV file that looks like this:
Jenny, jenny#example.com ,
Ricky, ricky#example.com ,
Josefina josefina#example.com ,
I'm trying to get this output:
users_array = [
['Jenny', 'jenny#example.com'], ['Ricky', 'ricky#example.com'], ['Josefina', 'josefina#example.com']
]
I've tried this:
users_array = Array.new
file = File.new('csv_file.csv', 'r')
file.each_line("\n") do |row|
puts row + "\n"
columns = row.split(",")
users_array.push columns
puts users_array
end
Unfortunately, in Terminal, this returns:
Jenny
jenny#example.com
Ricky
ricky#example.com
Josefina
josefina#example.com
Which I don't think will work for this:
users_array.each_with_index do |user|
add_page.form_with(:id => 'new_user') do |f|
f.field_with(:id => "user_email").value = user[0]
f.field_with(:id => "user_name").value = user[1]
end.click_button
end
What do I need to change? Or is there a better way to solve this problem?

Ruby's standard library has a CSV class with a similar api to File but contains a number of useful methods for working with tabular data. To get the output you want, all you need to do is this:
require 'csv'
users_array = CSV.read('csv_file.csv')
PS - I think you are getting the output you expected with your file parsing as well, but maybe you're thrown off by how it is printing to the terminal. puts behaves differently with arrays, printing each member object on a new line instead of as a single array. If you want to view it as an array, use puts my_array.inspect.

Assuming that your CSV file actually has a comma between the name and email address on the third line:
require 'csv'
users_array = []
CSV.foreach('csv_file.csv') do |row|
users_array.push row.delete_if(&:nil?).map(&:strip)
end
users_array
# => [["Jenny", "jenny#example.com"],
# ["Ricky", "ricky#example.com"],
# ["Josefina", "josefina#example.com"]]
There may be a simpler way, but what I'm doing there is discarding the nil field created by the trailing comma and stripping the spaces around the email addresses.

Related

How to read specific columns of a zipped CSV file

I used the code below to read the contents of a zipped CSV file.
Zip::ZipFile.foreach(file) do |entry|
istream = entry.get_input_stream
data = istream.read
#...
end
It gives me the entire content of the text (CSV) file with headers like below:
NAME AGE GENDER NAME1 29 MALE NAME2 30 FEMALE
but I need specific data of the column. For example, I want to display only the names (NAME). Please help me proceed with this.
Though your example shows ZipFile, you're really asking a CSV question. First, you should check the docs in http://www.ruby-doc.org/stdlib-2.0/libdoc/csv/rdoc/CSV.html
You'll find that if you parse your data with the :headers => true option, you'll get a CSV::table object that knows how to extract a column of data as follows. (For obvious reasons, I wouldn't code it this way -- this is for example only.)
require 'zip'
require 'csv'
csv_table = nil
Zip::ZipFile.foreach("x.csv.zip") do |entry|
istream = entry.get_input_stream
data = istream.read
csv_table = CSV.parse(data, :col_sep => " ", :headers => true)
end
With the data you gave, we need `col_sep => " " since you're using spaces as column separators. But now we can do:
>> csv_table["NAME"] # extract the NAME column
=> ["NAME1", "NAME2"]
First you can use this for reference:
http://www.ruby-doc.org/stdlib-2.0/libdoc/csv/rdoc/CSV.html
If you have a string you can do
array = CSV.parse("data")
This would give you an array of arrays, one for each line.
Now if you know that the first column for each line is the name you can just manipulate that array i.e
array.map { |line| line[0] }.join(",") # returns NAME,<name>,<name>,<name> ...

Taking json data and converting it to a CSV file

Okay... so new to Ruby here but loving it so far. My problem is I cannot get the data to go into the CSV files.
#!/usr/bin/env ruby
require 'date'
require_relative 'amf'
require 'json'
require 'csv'
amf = Amf.new
#This makes it go out 3 days
apps = amf.post( 'Appointments.getBetweenDates',
{ 'startDate' => Date.today, 'endDate' => Date.today + 4 }
)
apps.each do |app|
cor_md_params = { 'appId' => app['appID'], 'relId' => 7 }
cor_md = amf.post( 'Clinicians.getByAppIdAndRelId', cor_md_params ).first
#this is where it breaks ----->
CSV.open("ile.csv", "wb") do |csv|
csv << ["column1", "column2", "etc.", "etc.."]
csv << ([
# if added puts ([ I can display the info and then make a csv...
app['patFirstName'],
app['patMiddleName'],
app['patLastName'],
app['patBirthdate'],
app['patHin'],
app['patPhone'],
app['patCellPhone'],
app['patBusinessPhone'],
app['appTime'],
app['appID'],
app['patPostalCode'],
app['patProvince'],
app['locName'],
# note that this is not exactly accurate for follow-ups,
# where you have to replace the "1" with the actual value
# in weeks, days, months, etc
#app[ 'bookName' ], => not sure this is needed
cor_md['id'],
cor_md['providerCode'],
cor_md['firstName'],
cor_md['lastName']
].join(', '))
end
end
Now, if I remove the attempt to make the ile.cvs file and just output it with a puts, all the data shows. But I don't want to have to go into the terminal and create a csv file... I would rather just run the .rb program and have it created. Also, hopefully I am making the columns correctly as well...
The thought occurred to me that I could just add another puts above the output.
Or, better, insert a row into the array before I output it...
Really not sure what is best practice here and standards.
This is what I have done and attempted. How can I get it to cleanly output to a CSV file since my attempts are not working
Also, to clarify where it breaks, it does add the column names just not the JSON info that is parsed. I could also be completely doing this the wrong way or a way that isn't possible. I just do not know.
What kind of error do you get? Is it this one:
<<': undefined methodmap' for "something":String (NoMethodError)
I think, you should remove the .join(', ')
The << method of CSV accepts an array, but not a String
http://ruby-doc.org/stdlib-1.9.2/libdoc/csv/rdoc/CSV.html#method-i-3C-3C
So instead of:
cor_md['lastName']
].join(', '))
rather:
cor_md['lastName']
])
The problem with the loop (why it writes only 1 row of data)
In the body of your loop, you always reopen the file, and always rewrite what you added before. What you want to do, is probably this:
CSV.open("ile3.csv", "wb") do |csv|
csv << ["column1", "column2", "etc.", "etc.."]
apps.each do |app|
cor_md_params = { 'appId' => app['appID'], 'relId' => 7 }
cor_md = amf.post( 'Clinicians.getByAppIdAndRelId', cor_md_params ).first
#csv << your long array
end
end

CSV.generate and converters?

I'm trying to create a converter to remove newline characters from CSV output.
I've got:
nonewline=lambda do |s|
s.gsub(/(\r?\n)+/,' ')
end
I've verified that this works properly IF I load a variable and then run something like:
csv=CSV(variable,:converters=>[nonewline])
However, I'm attempting to use this code to update a bunch of preexisting code using CSV.generate, and it does not appear to work at all.
CSV.generate(:converters=>[nonewline]) do |csv|
csv << ["hello\ngoodbye"]
end
returns:
"\"hello\ngoodbye\"\n"
I've tried quite a few things as well as trying other examples I've found online, and it appears as though :converters has no effect when used with CSV.generate.
Is this correct, or is there something I'm missing?
You need to write your converter as as below :
CSV::Converters[:nonewline] = lambda do |s|
s.gsub(/(\r?\n)+/,' ')
end
Then do :
CSV.generate(:converters => [:nonewline]) do |csv|
csv << ["hello\ngoodbye"]
end
Read the documentation Converters .
Okay, above part I didn't remove, as to show you how to write the custom CSV converters. The way you wrote it is incorrect.
Read the documentation of CSV::generate
This method wraps a String you provide, or an empty default String, in a CSV object which is passed to the provided block. You can use the block to append CSV rows to the String and when the block exits, the final String will be returned.
After reading the docs, it is quite clear that this method is for writing to a csv file, not for reading. Now all the converters options ( like :converters, :header_converters) is applied, when you are reading a CSV file, but not applied when you are writing into a CSV file.
Let me show you 2 examples to illustrate this more clearly.
require 'csv'
string = <<_
foo,bar
baz,quack
_
File.write('a',string)
CSV::Converters[:upcase] = lambda do |s|
s.upcase
end
I am reading from a CSV file, so :converters option is applied to it.
CSV.open('a','r',:converters => :upcase) do |csv|
puts csv.read
end
output
# >> FOO
# >> BAR
# >> BAZ
# >> QUACK
Now I am writing into the CSV file, converters option is not applied.
CSV.open('a','w',:converters => :upcase) do |csv|
csv << ['dog','cat']
end
CSV.read('a') # => [["dog", "cat"]]
Attempting to remove newlines using :converters did not work.
I had to override the << method from csv.rb adding the following code to it:
# Change all CR/NL's into one space
row.map! { |element|
if element.is_a?(String)
element.gsub(/(\r?\n)+/,' ')
else
element
end
}
Placed right before
output = row.map(&#quote).join(#col_sep) + #row_sep # quote and separate
at line 21.
I would think this would be a good patch to CSV, as newlines will always produce bad CSV output.

Taking multiple lines from a file and creating hash

I'm taking a file and reading in it's contents and creating a hash based on newlines. I've been able to make a hash based on the contents of each line, but how can I create a hash based on the content of everything before the next blank newline? Below is what I have so far.
Input:
Title 49th parallel
URL http://artsweb.bham.ac.uk/
Domain artsweb.bham.ac.uk
Title ABAA booknet
URL http://abaa.org/
Domain abaa.org
Code:
File.readlines('A.cfg').each do |line|
unless line.strip.empty?
hash = Hash[*line.strip.split("\t")]
puts hash
end
puts "\n" if line.strip.empty?
end
Outputs:
{"Title"=>"49th parallel"}
{"URL"=>"http://artsweb.bham.ac.uk/"}
{"Domain"=>"artsweb.bham.ac.uk"}
{"Title"=>"ABAA booknet"}
{"URL"=>"http://abaa.org/"}
{"Domain"=>"abaa.org"}
Desired Output:
{"Title"=>"49th parallel", "URL"=>"http://artsweb.bham.ac.uk/", "Domain"=>"artsweb.bham.ac.uk"}
{"Title"=>"ABAA booknet", "URL"=>"http://abaa.org/", "Domain"=>"abaa.org"}
Modifying your existing code, this does what you want:
hash = {}
File.readlines('A.cfg').each do |line|
if line.strip.empty?
puts hash if not hash.empty?
hash = {}
puts "\n"
else
hash.merge!(Hash[*line.strip.split("\t")])
end
end
puts hash
You can likely simplify that depending on what you're actually doing with the data.
open('A.cfg', &:read)
.strip.split(/#$/{2,}/)
.map{|s| Hash[s.scan(/^(\S+)\s+(\S+)/)]}
gives
[
{
"Title" => "49th",
"URL" => "http://artsweb.bham.ac.uk/",
"Domain" => "artsweb.bham.ac.uk"
},
{
"Title" => "ABAA",
"URL" => "http://abaa.org/",
"Domain" => "abaa.org"
}
]
read the whole content of the file using read:
contents = ""
File.open('A.cfg').do |file|
contents = file.read
end
And then split the contents on two newline characters:
contents.split("\n\n")
And lastly, create a function pretty similar to what you already have to parse those chunks.
Please note that if you are working on windows it may happen that you need to split on a different sequence because of the carriage return character.

Parse CSV file with header fields as attributes for each row

I would like to parse a CSV file so that each row is treated like an object with the header-row being the names of the attributes in the object. I could write this, but I'm sure its already out there.
Here is my CSV input:
"foo","bar","baz"
1,2,3
"blah",7,"blam"
4,5,6
The code would look something like this:
CSV.open('my_file.csv','r') do |csv_obj|
puts csv_obj.foo #prints 1 the 1st time, "blah" 2nd time, etc
puts csv.bar #prints 2 the first time, 7 the 2nd time, etc
end
With Ruby's CSV module I believe I can only access the fields by index. I think the above code would be a bit more readable. Any ideas?
Using Ruby 1.9 and above, you can get a an indexable object:
CSV.foreach('my_file.csv', :headers => true) do |row|
puts row['foo'] # prints 1 the 1st time, "blah" 2nd time, etc
puts row['bar'] # prints 2 the first time, 7 the 2nd time, etc
end
It's not dot syntax but it is much nicer to work with than numeric indexes.
As an aside, for Ruby 1.8.x FasterCSV is what you need to use the above syntax.
Here is an example of the symbolic syntax using Ruby 1.9. In the examples below, the code reads a CSV file named data.csv from Rails db directory.
:headers => true treats the first row as a header instead of a data row. :header_converters => :symbolize parameter then converts each cell in the header row into Ruby symbol.
CSV.foreach("#{Rails.root}/db/data.csv", {:headers => true, :header_converters => :symbol}) do |row|
puts "#{row[:foo]},#{row[:bar]},#{row[:baz]}"
end
In Ruby 1.8:
require 'fastercsv'
CSV.foreach("#{Rails.root}/db/data.csv", {:headers => true, :header_converters => :symbol}) do |row|
puts "#{row[:foo]},#{row[:bar]},#{row[:baz]}"
end
Based on the CSV provided by the Poul (the StackOverflow asker), the output from the example code above will be:
1,2,3
blah,7,blam
4,5,6
Depending on the characters used in the headers of the CSV file, it may be necessary to output the headers in order to see how CSV (FasterCSV) converted the string headers to symbols. You can output the array of headers from within the CSV.foreach.
row.headers
Easy to get a hash in Ruby 2.3:
CSV.foreach('my_file.csv', headers: true, header_converters: :symbol) do |row|
puts row.to_h[:foo]
puts row.to_h[:bar]
end
Although I am pretty late to the discussion, a few months ago I started a "CSV to object mapper" at https://github.com/vicentereig/virgola.
Given your CSV contents, mapping them to an array of FooBar objects is pretty straightforward:
"foo","bar","baz"
1,2,3
"blah",7,"blam"
4,5,6
require 'virgola'
class FooBar
include Virgola
attribute :foo
attribute :bar
attribute :baz
end
csv = <<CSV
"foo","bar","baz"
1,2,3
"blah",7,"blam"
4,5,6
CSV
foo_bars = FooBar.parse(csv).all
foo_bars.each { |foo_bar| puts foo_bar.foo, foo_bar.bar, foo_bar.baz }
Since I hit this question with some frequency:
array_of_hashmaps = CSV.read("path/to/file.csv", headers: true)
puts array_of_hashmaps.first["foo"] # 1
This is the non-block version, when you want to slurp the whole file.

Resources