I've got a weird issue with Ruby. I want to read data from a file and put the data then into an array.
The weird thing is, it's working in another script which does basically, the same thing.
quoteArray = []
quoteFile = File.new("quotes.txt", "r") or die "Unable to open file..."
quoteFile.each_line { |line| quoteArray.push line }
puts quoteArray[0]
All I get out of this is an array with one element where the whole text file is in. What's wrong? Is it my machine? The text file? Any ideas?
Thanks in advance
quoteFile = File.read("quotes.txt").gsub(/\n?\r/, "\n").lines.to_a
You are printing quoteArray[0]. Try printing quoteArray.inspect and see what you get.
It works fine for me. Make sure that your text file has multiple lines in it and not just a one single big line.
Related
I have an input file and a batch file. When the batch file is executed using the System command,
a corresponding outfile is generated.
Now I want a particular text (position 350 to 357) from that outfile to be displayed on to my lineedit widget
Here is that part of my code:
system("C:/ORG_Class0178.bat")
Now the outfile will be generated
File.open("C:/ORG_Class0178_out.txt", 'r').each do |line|
var = line[350..357]
puts var
# To test whether the file is being read.
#responseLineEdit = Qt::LineEdit.new(self)
#responseLineEdit.setFont Qt::Font.new("Times NEw Roman", 12)
#responseLineEdit.resize 100,20
#responseLineEdit.move 210,395
#responseLineEdit.setText("#{var}")
end
When I do test whether the file is being read using puts statement, I get the exact required output in editor. However, the same text is not being displayed on LineEdit. Suggestions are welcome.
EDIT: A wired observation here. It works fine when I try to read the input file and display it , however it does not work with the output file. The puts statement does give the answer in editor confirming that output file does contain the required text. I am confused over this scenario.
There is nothing wrong with the code fragments shown.
Note that var is a local variable. Are the second and third code fragments in the same context? If they are in the same method, and var is not touched in-between, it will work.
If the fragments belong to different methods of the same class, than an instance variable (#var) will solve the problem.
If all that does not help, use Pry to chase the problem. Follow the link to find the pre-requisites and how to use. Place binding.pry in your code, and your program will stop at that line. Then inspect what your variables are doing.
try 'rb' instead of 'r'
File.open("C:/ORG_Class0178_out.txt", 'rb').each do |line|
var = line[350..357]
puts var
I am following Wicked cool ruby scripts book.
here,
there are two files, file_output = file_list.txt and oldfile_output = file_list.old. These two files contain list of all files the program went through and going to go through.
Now, the file is renamed as old file if a 'file_list.txt' file exists .
then, I am not able to understand the code.
Apparently every line of the file is read and the line is stored in oldfile hash.
Can some one explain from 4 the line?
And also, why is gets used here? why cant a .each method be used to read through every line?
if File.exists?(file_output)
File.rename(file_output, oldfile_output)
File.open(oldfile_output, 'rb') do |infile|
while (temp = infile.gets)
line = /(.+)\s{5,5}(\w{32,32})/.match(temp)
puts "#{line[1]} ---> #{line[2]}"
oldfile_hash[line[1]] = line[2]
end
end
end
Judging from the redundant use of quantifiers ({5,5} and {32,32}) in the regex (which would be better written as {5}, {32}), it looks like the person who wrote that code is not a professional Ruby programmer. So you can assume that the choice taken in the code is not necessarily the best.
As you pointed out, the code could have used each instead of while with gets. The latter approach is sort of an old-school Ruby way of doing it. There is nothing wrong in using it. Until the end of file is reached, gets will return a string, and when it does reach the end of file, gets will return nil, so the while loop works as the same when you use each; in each iteration, it reads the next line.
It looks like each line is supposed to represent a key-value pair. The regex assumes that the key is not an empty string, and that the key and the value are separated by exactly five spaces, and the the value consists of exactly thirty-two letters. Each key-value pair is printed (perhaps for monitoring the progress), and is stored in oldfile_hash, which is most likely a hash.
So the point of using .gets is to tell when the file is finished being read. Essentially, it's tied to the
while (condition)
....
end
block. So gets serves as a little method that will keep giving ruby the next line of the file until there is no more lines to give.
In my application, the user must upload a text document, the contents of which are then parsed by the receiving controller action. I've gotten the document to upload successfully, but I'm having trouble reading its contents.
There are several threads on this issue. I've tried more or less everything recommended on these threads, and I'm still unable to resolve the problem.
Here is my code:
file_data = params[:file]
contents = ""
if file_data.respond_to?(:read)
contents = file_data.read
else
if file_data.respond_to?(:path)
File.open(file_data, 'r').each_line do |line|
elts = line.split
#
#
end
end
end
So here are my problems:
file_data doesn't 'respond_to?' either :read or :path. According to some other threads on the topic, if the uploaded file is less than a certain size, it's interpreted as a string and will respond to :read. Otherwise, it should respond to :path. But in my code, it responds to neither.
If I try to take out the if statements and straight away attempt File.open(file_data, 'r'), I get an error saying that the file wasn't found.
Can someone please help me find out what's wrong?
PS, I'm really sorry that this is a redundant question, but I found the other threads unhelpful.
Are you actually storing the file? Because if you are not, of course it can't be found.
First, find out what you're actually getting for file_data by adding debug output of file_data.inspect. It maybe something you don't expect, especially if form isn't set up correctly (i.e. :multipart => true).
Rails should enclose uploaded file in special object providing uniform interface, so that something as simple as this should work:
file_data.read.each_line do |line|
elts = line.split
#
#
end
I'm trying to use Sphinx Search Server to index a really huge file (around 14gb).
The file is whitespace separated, one entry per line.
To be able to use it with Sphinx, I need to provide a xml file to the Sphinx server.
How can I do it without killing my computer ?
What is the best strategy? Should I try to split the main file in several little files? What's the best way to do it?
Note: I'm doing it in Ruby, but I'm totally open to other hints.
Thanks for your time.
I think the main idea would be to parse the main file line by line, while generating a result XML. And every time it gets large enough, to feed it to Sphinx. Rinse and repeat.
What parsing do you need to do? If the transformations are restricted to just one line in the input at once and not too complicated, I would use awk instead of Ruby...
I hate guys who doesn't write solution after a question. So I'll try to don't be one of them, hopefully it will help somebody.
I added a simple reader method to the File class then used it to loop on the file based on a chunk size of my choice. Quite simple actually, working like a charm with Sphinx.
class File
# New static method
def self.seq_read(file_path,chunk_size=nil)
open(file_path,"rb") do |f|
f.each_chunk(chunk_size) do |chunk|
yield chunk
end
end
end
# New instance method
def each_chunk(chunk_size=1.kilobyte)
yield read(chunk_size) until eof?
end
end
Then just use it like this:
source_path = "./my_very_big_file.txt"
CHUNK_SIZE = 10.megabytes
File.seq_read(source_path, CHUNK_SIZE) do |chunk|
chunk.each_line do |line|
...
end
end
I am sure this is an easy one; I just couldn't find the answer immediately from Google.
I know I could do this (right?):
text = ""
File.open(path).each_line do |line|
text += line
end
# Do something with text
But that seems a bit excessive, doesn't it? Or is that the way one would do it in Ruby?
IO.read() is what you're looking for.
File is a subclass of IO, so you may as well just use:
text = File.read(path)
Can't get more intuitive than that.
What about IO.read()?
Edit: IO.read(), as an added bonus, closes the file for you.
First result I found when searching.
I wanted to change the mode, which doesn't seem possible with IO.read, unless I'm wrong?
Anyway, you can do this:
data = File.open(path,'rb',&:read)
It's also good for when you want to use any of the other options:
https://ruby-doc.org/core/IO.html#method-c-new