I created a CSV file, no headers, two columns per row. I.e.:
ARG001,ARG001a
ARG002,ARG002a
ARG003,ARG003a
I can read it and print out a specific row of the array:
require 'csv'
data = CSV.read("recTest.csv")
print data[0]
With my output looking like this:
["ARG001", "ARG001a"]
What I am trying to do is pass as many rows of data to a function that'll use them within the query string of a URL. I.e.:
start firefox
https://desiredSite.com/status?queryStringArg1=ARG001&querySTringArg2=ARG001a
Extremely new with Ruby, any help would be great. Thx in advance!
Related
My goal is to import a one column of a CSV file into a Ruby array. This is for a self-contained Ruby script, not an application. I'll just be running the script in Terminal and getting an output.
I'm having trouble finding the best way to import the file and finding the best way to dynamically insert the name of the file into that line of code. The filename will be different each time, and will be passed in by the user. I'm using $stdin.gets.chomp to ask the user for the filename, and setting it equal to file_name.
Can someone help me with this? Here's what I have for this part of the script:
require 'csv'
zip_array = CSV.read("path/to/file_name.csv")
and I need to be able to insert the proper file path above. Is this correct? And how do I get that path name in there? Maybe I'll need to totally re-structure my script, but any suggestions on how to do this?
There are two questions here, I think. The first is about getting user input from the command line. The usual way to do this is with ARGV. In your program you could do file_name = ARGV[0] so a user could type ruby your_program.rb path/to/file_name.csv on the command line.
The next is about reading CSVs. Using CSV.read will take the whole CSV, not just a single column. If you want to choose one column of many, you are likely better off doing:
zip_array = []
CSV.foreach(file_name) { |row| zip_array << row[whichever_column] }
Okay, first problem:
a) The file name will be different on each run (I'm supposing it will always be a CSV file, right?)
You can solve this problem with creating a folder, say input_data inside your Ruby script. Then do:
Dir.glob('input_data/*.csv')
This will produce an array of ALL files inside that folder that end with CSV. If we assume there will be only 1 file at a time in that folder (with a different name), we can do:
file_name = Dir.glob('input_data/*.csv')[0]
This way you'll dynamically get the file path, no matter what the file is named. If the csv file is inside the same directory as your Ruby script, you can just do:
Dir.glob('*.csv')[0]
Now, for importing only 1 column into a Ruby array (let's suppose it's the first column):
require 'csv'
array = []
CSV.foreach(file_name) do |csv_row|
array << csv_row[0] # [0] for the first column, [1] for the second etc.
end
What if your CSV file has headers? Suppose your column name is 'Total'. You can do:
require 'csv'
array = []
CSV.foreach(file_name, headers: true) do |csv_row|
array << csv_row['Total']
end
Now it doesn't matter if your column is the 1st column, the 3rd etc, as long as it has a header named 'Total', Ruby will find it.
CSV.foreach reads your file line-by-line and is good for big files. CSV.read will read it at once but using it you can make your code more concise:
array = CSV.read(, headers: true).map do |csv_row|
csv_row['Total']
end
Hope this helped.
First, you need to assign the returned value from $stdin.gets.chomp to a variable:
foo = $stdin.gets.chomp
Which will assign the entered input to foo.
You don't need to use $stdin though, as gets will use the standard input channel by default:
foo = gets.chomp
At that point use the variable as your read parameter:
zip_array = CSV.read(foo)
That's all basic coding and covered in any intro book for a language.
I am learning Ruby and trying to manipulate Excel data.
my goal:
To be able to extract email addresses from an excel file and place them in a text file one per line and add a comma to the end.
my ideas:
i think my answer lies in the use of spreadsheet and File.new.
What I am looking for is direction. I would like to hear any tips or rather hints to accomplish my goal. thanks
Please do not post exact code only looking for direction would like to figure it out myself...
thanks, karen
UPDATE::
So, regex seems to be able to find all matching strings and store them into an array. I´m having some trouble setting that up but should be able to figure it out....but for right now to get started I will extract only the column labeled "E Mail"..... the question I have now is:
`parse_csv = CSV.parse(read_csv, :headers => true)`
The default value for :skip_blanks is set to false.. I need to set it to true but nowhere can I find the correct syntax for doing so... I was assumming something like
`parse_csv = CSV.parse(read_csv, :headers => true :skip_blanks => true)`
But no.....
save your excel file as csv (comma separated value) and work with Ruby's libraries
besides spreadsheet (which can read and write), you can read Excel and other file types with with RemoteTable.
gem install remote_table
and
require 'remote_table'
t = RemoteTable.new('/path/to/file.xlsx', headers: :first_row)
when you write the CSV, as #aug2uag says, you can use ruby's standard library (no gem install required):
require 'csv'
puts [name, email].to_csv
Personally, I'd keep it as simple as possible and use a CSV.
Here is some pseudocode of how that would work:
read in your file line by line
extract your fields using regex, or cell count (depending on how consistent the email address location is), and insert into an arry
iterate through the array and write the values in the fashion you wish (to console, or file)
The code in the comment you had is a great start, however, puts will only write to console, not file. You will also need to figure out how you are going to know you are getting the email address.
Hope this helps.
Hey guys I'm writing a ruby program that reads a database of food items and recipes that is in CSV format, and writes it back to a file. I'm having issues writing to a CSV file correctly
I want to write an objects attributes to a CSV file
csv_text = CSV.open("FoodDB1.txt","w") do |i|
##dataList.each do |j|
if j.get_type == "b"
i << [j.name,j.get_type,j.cal]
elsif j.get_type == "r"
i << [j.name,j.get_type,j.print_bFood]
end
end
end
I have two types of objects, basic food and a recipe. Both are stored in the dataList array. I check each object for its type, if it's a basic food, writing it is easy since it is just three simple fields. If it is a recipe, I write the name,type,and the basic foods that make up that recipe.
The issue I'm having is at this line
i << [j.name,j.get_type,j.print_bFood]
So it prints out the name of the recipe, the type(whether its a basic food or a recipe) and then finally the list of foods in the recipe. That is where I'm having issues.
bFood is an array of basic foods that is stored in the object, and I'm having trouble adding it to the CSV row. I tried making a method(which is print_bFood) that returns a string of the combined array using .join(","), but because of the comma in the string, when CSV writes it to a file it is wrapped in quotes
"PB&J Sandwich,r,"Jelly,Peanut butter,Bread slice, Bread slice""
I want it to look like this
"PB&J Sandwich,r,Jelly,Peanut butter,Bread slice, Bread slice"
Any ideas on what can help. I've looked for ways to do this and I just can't think of anything anymore.
One idea I had was if I had the ability to just add on to a row, I could iterate through the bFood array and add each one to the row, but I haven't found any functionality that can do that.
If I read this correctly you should just need...
i << [j.name, j.get_type, j.bFood].flatten
I have a CSV file called "A.csv". I need to generate a new CSV file called "B.csv" with data from "A.csv".
I will be using a subset of columns from "A.csv" and will have to update one column's values to new values in "B.csv". Ultimately, I will use this data from B.csv to validate against a database.
How do I create a new CSV file?
How do I copy the required columns' data from A.csv to "B.csv"?
How do I append values for a particular column?
I am new to Ruby, but I am able to read CSV to get an array or hash.
As mikeb pointed out, there are the docs - http://ruby-doc.org/stdlib-1.9.3/libdoc/csv/rdoc/CSV.html - Or you can follow along with the examples below (all are tested and working):
To create a new file:
In this file we'll have two rows, a header row and data row, very simple CSV:
require "csv"
CSV.open("file.csv", "wb") do |csv|
csv << ["animal", "count", "price"]
csv << ["fox", "1", "$90.00"]
end
result, a file called "file.csv" with the following:
animal,count,price
fox,1,$90.00
How to append data to a CSV
Almost the same formula as above only instead of using "wb" mode, we'll use "a+" mode. For more information on these see this stack overflow answer: What are the Ruby File.open modes and options?
CSV.open("file.csv", "a+") do |csv|
csv << ["cow", "3","2500"]
end
Now when we open our file.csv we have:
animal,count,price
fox,1,$90.00
cow,3,2500
Read from our CSV file
Now you know how to copy and to write to a file, to read a CSV and therefore grab the data for manipulation you just do:
CSV.foreach("file.csv") do |row|
puts row #first row would be ["animal", "count", "price"] - etc.
end
Of course, this is like one of like a hundred different ways you can pull info from a CSV using this gem. For more info, I suggest visiting the docs now that you have a primer: http://ruby-doc.org/stdlib-1.9.3/libdoc/csv/rdoc/CSV.html
Have you seen Ruby's CSV class? It seems pretty comprehensive. Check it out here:
http://ruby-doc.org/stdlib-1.9.3/libdoc/csv/rdoc/CSV.html
You will probably want to use CSV::parse to help Ruby understand your CSV as the table of data that it is and enable easy access to values by header.
Unfortunately, the available documentation on the CSV::parse method doesn't make it very clear how to actually use it for this purpose.
I had a similar task and was helped much more by How to Read & Parse CSV Files With Ruby on rubyguides.com than by the CSV class documentation or by the answers pointing to it from here.
I recommend reading that page in its entirety. The crucial part is about transforming a given CSV into a CSV::Table object using:
table = CSV.parse(File.read("cats.csv"), headers: true)
Now there's documentation on the CSV::Table class, but again you might be helped more by the clear examples on the rubyguides.com page. One thing I'll highlight is that when you tell .parse to expect headers, the resulting table will treat the first row of data as row [0].
You will probably be especially interested in the .by_col method available for your new Table object. This will allow you to iterate through different column index positions in the input and/or output and either copy from one to the other or add a new value to the output. If I get it working, I'll come back and post an example.
I need some help with a Ruby script I can call from the console. The script needs to parse a simple .txt file with comma separated values.
value 1, value2, value3, etc...
The values needs to be added to the database.
Any suggestions?
array = File.read("csv_file.txt").split(",").map(&:strip)
You will get the values in the array and use it to store to database. If you want more functions, you can make use of FasterCSV gem.
Ruby 1.9.2 has a very good CSV library which is useful for this stuff: http://www.ruby-doc.org/stdlib/libdoc/csv/rdoc/index.html
On earlier versions of Ruby you could use http://fastercsv.rubyforge.org/ (which essentially became CSV in 1.9.2)
You could do it manually by reading the file into a string and using .split(',') but I'd go with one of the libraries above.
Quick and dirty solution:
result = []
File.open("<path-to-file>","r") do |handle|
handle.each_line do |line|
result << line.split(",").strip
end
end # closes automatically when EOF reached
result.flatten!
result # => big array of values
Now you can iterate the result array and save the values to the database.
This simple file iteration doesn't take care for order or special fields, because it wasn't mentioned in the question.
Something easy to get you started:
IO.readlines("csv_file.txt", '').each do |line|
values = line.split(",").collect(&:strip)
# do something with the values?
end
Hope this helps.