the problem is it cannot print all the text of the from a .txt file. I am able to print the first 3 lines of the txt file but not the rest. So far, I am getting an error which is in print_album': undefined local variable or methodtracks' for main:Object (NameError).
Here's the code:
*I know using global variable is no good in Ruby but this exercise ask me to do it.
module Genre
POP, CLASSIC, JAZZ, ROCK = *1..4
end
$genre_names = ['Null', 'Pop', 'Classic', 'Jazz', 'Rock']
class Album
# NB: you will need to add tracks to the following and the initialize()
attr_accessor :title, :artist, :genre, :tracks
# complete the missing code:
def initialize (atitle, aartist, agenre, arrtrk)
# insert lines here
#genre = agenre
#tracks = arrtrk
#title = atitle
#artist = aartist
end
end
class Track
attr_accessor :ttitle, :tlocation
def initialize (tname, tloc)
#ttitle = tname
#tlocation = tloc
end
end
# Reads in and returns a single track from the given file
def read_track music_file
mytrk_name = music_file.gets
mytrk_location = music_file.gets
mytrk = Track.new(mytrk_name, mytrk_location)
mytrk
end
# Returns an array of tracks read from the given file
def read_tracks music_file
count = music_file.gets().to_i
tracks = Array.new
$i = 0
# Put a loop here which increments an index to read the tracks
while $i < count do
track = read_track(music_file)
tracks << track
$i += 1
end
tracks
end
# Takes an array of tracks and prints them to the terminal
def print_tracks tracks
# print all the tracks use: tracks[x] to access each track.
$i = 0
while $i < tracks.length do
print_track(tracks[$i])
$i +=1
end
tracks
end
# Reads in and returns a single album from the given file, with all its tracks
def read_album music_file
# read in all the Album's fields/attributes including all the tracks
# complete the missing code
album_title = music_file.gets
album_artist = music_file.gets
album_genre = music_file.gets.to_i
tracks = read_tracks(music_file)
album = Album.new(album_title, album_artist, album_genre, tracks)
album
end
# Takes a single album and prints it to the terminal along with all its tracks
def print_album album
# print out all the albums fields/attributes
# Complete the missing code.
puts 'Album title is '+ album.title
puts 'Artist is ' + album.artist
puts 'Genre is ' + album.genre.to_s
puts $genre_names[album.genre]
# print out the tracks
print_tracks(tracks)
end
# Takes a single track and prints it to the terminal
def print_track track
puts('Track title is: ' + track.ttitle)
puts('Track file location is: ' + track.tlocation)
end
# Reads in an album from a file and then print the album to the terminal
def main
music_file = File.new("album.txt", "r")
album = read_album(music_file)
music_file.close()
print_album(album)
end
main
Here's is the album.txt
Greatest Hits
Neil Diamond
1
3
Crackling Rose
sounds/01-Cracklin-rose.wav
Soolaimon
sounds/06-Soolaimon.wav
Sweet Caroline
sounds/20-Sweet_Caroline.wav
Currently my output is :
Album title is Greatest Hits
Artist is Neil Diamond
Genre is 1
Pop
Expected output is :
Album title is Greatest Hits
Artist is Neil Diamond
Genre is 1
Pop
Track title is: Crackling Rose
Track file location is: sounds/01-Cracklin-rose.wav
Track title is: Soolaimon
Track file location is: sounds/06-Soolaimon.wav
Track title is: Sweet Caroline
Track file location is: sounds/20-Sweet_Caroline.wav
The problem is inside your def print_album album method. On the last line of the method it uses print_tracks(tracks), but tracks variable is undefined (that's exactly what error tells you).
You need to call print_tracks(album.tracks)
Related
class Player
def initialize(hp, attack, defence, gold)
#hp = hp
#attack = attack
#defence = defence
#gold = gold
#inventory = inventory
end
def inventory
#inventory = []
end
def buy(item)
if #gold >= item.price
#gold-=item.price
puts "You hand over #{item.price} gold, and get the #{item.name}."
puts "You have #{gold} gold left over."
#inventory.push([item.name,item.price,item.attack,item.defence])
puts "ITEMS IN INV: #{#inventory}" # output: ITEMS IN INV: [["Dagger", 4, 1, 0], ["Mucky Tunic", 2, 0, 2]]
else
puts "You can't afford this item."
end
end
end
player = Player.new(10,1,2,6)
puts player.inventory.inspect # output: []
The inventory.push line pushes the element to the array while it is inside the method, but when returned outside the method, the inventory array is empty. This is confusing because other variables that were changed inside that method in the same way come back as altered.
sample output when printed from inside the buy method:
ITEMS IN INV: [["Dagger", 4, 1, 0], ["Mucky Tunic", 2, 0, 2]]
output with player.inventory.inspect outside of the method:
[]
Whenever you call your inventory method:
def inventory
#inventory = []
end
... it assigns a new (empty) array to #inventory, thus overwriting any existing items.
The correct way is to either assign #inventory in initialize and just return it from within the getter:
class Player
def initialize(hp, attack, defence, gold)
#hp = hp
#attack = attack
#defence = defence
#gold = gold
#inventory = []
end
def inventory
#inventory
end
# ...
end
or to not assign it at all in initialize and use the conditional assignment operator:
class Player
def initialize(hp, attack, defence, gold)
#hp = hp
#attack = attack
#defence = defence
#gold = gold
end
def inventory
#inventory ||= []
end
# ...
end
which will assign [] to #inventory only if it was nil or false (i.e. the first time you call inventory).
A getter that just returns the corresponding instance variable (as in the former example) can also be created via attr_reader:
class Player
attr_reader :inventory
# ...
end
I figured it out 10 seconds after posting this, after messing about with it for an hour.
I needed to add inventory to def initialize, and then pass an empty array to player = Player.new(10,1,2,6) so it became player = Player.new(10,1,2,6,[]).
I still don't know why this works.
I start with an empty array, and a Hash of key, values.
I would like to iterate over the Hash and compare it against the empty array. If the value for each k,v pair doesn't already exist in the array, I would like to create an object with that value and then access an object method to append the key to an array inside the object.
This is my code
class Test
def initialize(name)
#name = name
#values = []
end
attr_accessor :name
def values=(value)
#values << value
end
def add(value)
#values.push(value)
end
end
l = []
n = {'server_1': 'cluster_x', 'server_2': 'cluster_y', 'server_3': 'cluster_z', 'server_4': 'cluster_x', 'server_5': 'cluster_y'}
n.each do |key, value|
l.any? do |a|
if a.name == value
a.add(key)
else
t = Test.new(value)
t.add(key)
l << t
end
end
end
p l
I would expect to see this:
[
#<Test:0x007ff8d10cd3a8 #name=:cluster_x, #values=["server_1, server_4"]>,
#<Test:0x007ff8d10cd2e0 #name=:cluster_y, #values=["server_2, server_5"]>,
#<Test:0x007ff8d10cd1f0 #name=:cluster_z, #values=["server_3"]>
]
Instead I just get an empty array.
I think that the condition if a.name == value is not being met and then the add method isn't being called.
#Cyzanfar gave me a clue as to what to look for, and I found the answer here
https://stackoverflow.com/a/34904864/5006720
n.each do |key, value|
found = l.detect {|e| e.name == value}
if found
found.add(key)
else
t = Test.new(value)
t.add(key)
l << t
end
end
#ARL you're almost there! The last thing you need to consider is when found actually returns an object since detect will find a matching one at some point.
n.each do |key, value|
found = l.detect {|e| e.name == value}
if found
found.add(key)
else
t = Test.new(value)
t.add(key)
l << t
end
end
You actually only want to add a new instance of Test when found return nil. This code should yield your desired output:
[
#<Test:0x007ff8d10cd3a8 #name=:cluster_x, #values=["server_1, server_4"]>,
#<Test:0x007ff8d10cd2e0 #name=:cluster_y, #values=["server_2, server_5"]>,
#<Test:0x007ff8d10cd1f0 #name=:cluster_z, #values=["server_3"]>
]
I observe two things in your code :
def values=(value)
#values << value
def add(value)
#values.push(value)
two methods do the same thing, pushing a value, as << is a kind of syntactic sugar meaning push
you have changed the meaning of values=, which is usually reserved for a setter method, equivalent to attire_writer :values.
Just to illustrate that there are many ways to do things in Ruby, I propose the following :
class Test
def initialize(name, value)
#name = name
#values = [value]
end
def add(value)
#values << value
end
end
h_cluster = {} # intermediate hash whose key is the cluster name
n = {'server_1': 'cluster_x', 'server_2': 'cluster_y', 'server_3': 'cluster_z',
'server_4': 'cluster_x', 'server_5': 'cluster_y'}
n.each do | server, cluster |
puts "server=#{server}, cluster=#{cluster}"
cluster_found = h_cluster[cluster] # does the key exist ? => nil or Test
# instance with servers list
puts "cluster_found=#{cluster_found.inspect}"
if cluster_found
then # add server to existing cluster
cluster_found.add(server)
else # create a new cluster
h_cluster[cluster] = Test.new(cluster, server)
end
end
p h_cluster.collect { | cluster, servers | servers }
Execution :
$ ruby -w t.rb
server=server_1, cluster=cluster_x
cluster_found=nil
server=server_2, cluster=cluster_y
cluster_found=nil
server=server_3, cluster=cluster_z
cluster_found=nil
server=server_4, cluster=cluster_x
cluster_found=#<Test:0x007fa7a619ae10 #name="cluster_x", #values=[:server_1]>
server=server_5, cluster=cluster_y
cluster_found=#<Test:0x007fa7a619ac58 #name="cluster_y", #values=[:server_2]>
[#<Test:0x007fa7a619ae10 #name="cluster_x", #values=[:server_1, :server_4]>,
#<Test:0x007fa7a619ac58 #name="cluster_y", #values=[:server_2, :server_5]>,
#<Test:0x007fa7a619aac8 #name="cluster_z", #values=[:server_3]>]
I'm using a text file with lines of movies. If a user inputs Oz, I want to output all the movies in the file that have the word Oz in it.
This is what I have so far.
puts "Enter the keyword you want to search for: "
keyword = gets
movies_file = File.new("movies.txt", "r")
movies = movies_file.read
movies_list = movies.split(" ")
match_list = []
movies_list.each do |w|
matchObj = w.match(keyword)
if matchObj then
matchlist.push(matchObj.captures[0])
end
end
match_list.each do |title|
puts title
end
Presuming you've got the file organized like this:
Wizard of Oz
Battlefield Earth
Twilight
Ozymandias
Then you can read it in this way:
lines = File.readlines('movies.txt').map(&:chomp)
Then to find matching lines:
matches = lines.grep(phrase)
There's no need for all the each stuff. Also the then on an if is almost never put in there, it's just useless decoration.
I'm trying to set up a program to help me take care of grading for students in a class. I've set it up to make a class of student then to read in from the file (something I'm not very familiar with in Ruby) via an array. My programming experience is in java so if there are errors that can be explained by that I apologize. Thank you in advance for your help.
class Student
def initialize(str_LastName, str_FirstName, arr_Score)
#str_LastName = str_LastName
#str_FirstName = str_FirstName
#arr_Score = arr_Score
str_Grade = ""
int_OutOf = 415
end
def get_LastName
str_LastName
end
def get_FirstName
str_FirstName
end
def get_Grade
str_Grade
end
def set_TotalScore()
sum = 0
arr_Score.each do |item|
sum += item
end
arr_Score[12] = sum
end
def set_Grade
if arr_Score[12]/int_OutOf >= 0.9
str_Grade = "A"
elsif arr_Score[12]/int_OutOf >= 0.8
str_Grade = "B"
elsif arr_Score[12]/int_OutOf >= 0.7
str_Grade = "C"
elsif arr_Score[12]/int_OutOf >= 0.6
str_Grade = "D"
else
str_Grade = "F"
end
end
end
def main
file_name = "Grades"
arr_students = Array.new(31)
arr_scores = Array.new(12)
int_i = 0
file_io = open(file_name).readlines.each do |line|
array = line.split(",").map(&:strip)
student = Student.new(array[0],array[1],array[2..-2]) #the final element in the array is for the final score
arr_students[int_i] = student
puts "read #{arr_students[int_i]}"
end
file_name = "Graded"
file_io = open(file_name,"a+")
arr_students.each do |student|
set_TotalScore
set_Grade
file.io_write(student)
puts "write #{student}"
end
end
main if __FILE__==$0
Here is my run at it. I tried to stay true in general to the original intent of your code while introducing more Rubyish ways of doing things.
class Student
def initialize(firstname, lastname, *scores)
#firstname, #lastname, #scores = firstname, lastname, scores
end
def total_score
#scores.map(&:to_i).inject(:+)
end
def grade
raise "TOO HIGH!" if total_score > MAX_SCORE
case total_score / MAX_SCORE
when 0.9..1.0; "A"
when 0.8...0.9; "B"
when 0.7...0.8; "C"
when 0.6...0.7; "D"
else "F"
end
end
def to_s
"#{#lastname}, #{#firstname}: #{total_score}, #{grade}"
end
end
MAX_SCORE = 415.0
DATA.each_line do |line|
arr = line.split(",").map(&:strip)
student = Student.new *arr
puts student
end
__END__
Herb,Goldberg,22,99,44,22,88,88
Mark,Sullivan,77,88,88,44,33
You can read and write to files like this(not tested):
outfile = File.open("Graded", "a+")
File.open("Grades").each_line do |line|
...
outfile.puts student
end
outfile.close
We can not easily reproduce your code because you open a file called "Grades" and we do not have or know of its content.
You should also add some code to first check whether your file exists, before continuing - right now your script exits with a Errno::ENOENT.
I would also suggest putting the logic in main into your class instead - let your class handle everything.
In the part:
if __FILE__ == $PROGRAM_NAME
end
You can then simply initialize your class with a simple call such as:
Foobar.new(ARGV)
You described the "Grades" file but I did not understand what you wrote - it would be easier if you could link in to a sample, like via a pastie or gist, then link it in; and to also say what the part is that is not working, which is also unclear.
The style issues are secondary, I consider your code ok - the other poster here does not.
You should go through codecademy to get your ruby syntax down.
To access your initialized instance variables (#str_LastName (which should be #last_name), etc) you need to use "attr_reader :str_LastName", preferably at the top of the class. That'll definite you getter (setter is attr_writer, both is attr_accessor).
You can also do a sum on an array like this: [1,4,6,7].inject(:+).
Does Java not allow case statements? You should use that in set_grade. You also don't need to initialize str_Grade. In set grade, you could do #grade_letter ||= "A", and then calling set_grade will return that value on each call.
I didn't look through your main method. It's ugly though. Ruby methods probably shouldn't be more than 5 lines long.
Python 3 program allows people to choose from list of employee names.
Data held on text file look like this: ('larry', 3, 100)
(being the persons name, weeks worked and payment)
I need a way to assign each part of the text file to a new variable,
so that the user can enter a new amount of weeks and the program calculates the new payment.
Below is my code and attempt at figuring it out.
import os
choices = [f for f in os.listdir(os.curdir) if f.endswith(".txt")]
print (choices)
emp_choice = input("choose an employee:")
file = open(emp_choice + ".txt")
data = file.readlines()
name = data[0]
weeks_worked = data[1]
weekly_payment= data[2]
new_weeks = int(input ("Enter new number of weeks"))
new_payment = new_weeks * weekly_payment
print (name + "will now be paid" + str(new_payment))
currently you are assigning the first three lines form the file to name, weeks_worked and weekly_payment. but what you want (i think) is to separate a single line, formatted as ('larry', 3, 100) (does each file have only one line?).
so you probably want code like:
from re import compile
# your code to choose file
line_format = compile(r"\s*\(\s*'([^']*)'\s*,\s*(\d+)\s*,\s*(\d+)\s*\)")
file = open(emp_choice + ".txt")
line = file.readline() # read the first line only
match = line_format.match(line)
if match:
name, weeks_worked, weekly_payment = match.groups()
else:
raise Exception('Could not match %s' % line)
# your code to update information
the regular expression looks complicated, but is really quite simple:
\(...\) matches the parentheses in the line
\s* matches optional spaces (it's not clear to me if you have spaces or not
in various places between words, so this matches just in case)
\d+ matches a number (1 or more digits)
[^']* matches anything except a quote (so matches the name)
(...) (without the \ backslashes) indicates a group that you want to read
afterwards by calling .groups()
and these are built from simpler parts (like * and + and \d) which are described at http://docs.python.org/2/library/re.html
if you want to repeat this for many lines, you probably want something like:
name, weeks_worked, weekly_payment = [], [], []
for line in file.readlines():
match = line_format.match(line)
if match:
name.append(match.group(1))
weeks_worked.append(match.group(2))
weekly_payment.append(match.group(3))
else:
raise ...