我一直在为Coursera Rails入门课程进行这项作业。我们受命编写一个程序来计算文本文件中的最大单词频率。我们被指示创建一种方法:
highest_wf_count
中的最大次数。highest_wf_words
中。[当我运行提供给我们的rspec测试时,一个测试失败了。我打印了输出以查看问题出在哪里,但无法解决。
这是我的代码,rspec测试以及得到的内容:
class LineAnalyzer
attr_accessor :highest_wf_count
attr_accessor :highest_wf_words
attr_accessor :content
attr_accessor :line_number
def initialize(content, line_number)
@content = content
@line_number = line_number
@highest_wf_count = 0
@highest_wf_words = highest_wf_words
calculate_word_frequency
end
def calculate_word_frequency()
@highest_wf_words = Hash.new(0)
@content.split.each do |word|
@highest_wf_words[word.downcase!] += 1
if @highest_wf_words.has_key?(word)
@highest_wf_words[word] += 1
else
@highest_wf_words[word] = 1
end
@highest_wf_words.sort_by{|word, count| count}
@highest_wf_count = @highest_wf_words.max_by {|word, count| count}
end
end
def highest_wf_count()
p @highest_wf_count
end
end
这是rspec代码:
require 'rspec'
describe LineAnalyzer do
subject(:lineAnalyzer) { LineAnalyzer.new("test", 1) }
it "has accessor for highest_wf_count" do
is_expected.to respond_to(:highest_wf_count)
end
it "has accessor for highest_wf_words" do
is_expected.to respond_to(:highest_wf_words)
end
it "has accessor for content" do
is_expected.to respond_to(:content)
end
it "has accessor for line_number" do
is_expected.to respond_to(:line_number)
end
it "has method calculate_word_frequency" do
is_expected.to respond_to(:calculate_word_frequency)
end
context "attributes and values" do
it "has attributes content and line_number" do
is_expected.to have_attributes(content: "test", line_number: 1)
end
it "content attribute should have value \"test\"" do
expect(lineAnalyzer.content).to eq("test")
end
it "line_number attribute should have value 1" do
expect(lineAnalyzer.line_number).to eq(1)
end
end
it "calls calculate_word_frequency when created" do
expect_any_instance_of(LineAnalyzer).to receive(:calculate_word_frequency)
LineAnalyzer.new("", 1)
end
context "#calculate_word_frequency" do
subject(:lineAnalyzer) { LineAnalyzer.new("This is a really really really cool cool you you you", 2) }
it "highest_wf_count value is 3" do
expect(lineAnalyzer.highest_wf_count).to eq(3)
end
it "highest_wf_words will include \"really\" and \"you\"" do
expect(lineAnalyzer.highest_wf_words).to include 'really', 'you'
end
it "content attribute will have value \"This is a really really really cool cool you you you\"" do
expect(lineAnalyzer.content).to eq("This is a really really really cool cool you you you")
end
it "line_number attribute will have value 2" do
expect(lineAnalyzer.line_number).to eq(2)
end
end
end
这是rspec输出:
13 examples, 1 failure
Failed examples:
rspec ./course01/module02/assignment-Calc-Max-Word-Freq/spec/line_analyzer_spec.rb:42 # LineAnalyzer#calculate_word_frequency highest_wf_count value is 3
我的输出:
#<LineAnalyzer:0x00007fc7f9018858 @content="This is a really really really cool cool you you you", @line_number=2, @highest_wf_count=[nil, 10], @highest_wf_words={"this"=>2, nil=>10, "is"=>1, "a"=>1, "really"=>3, "cool"=>2, "you"=>3}>
我尝试了几种方法来解决这些问题,但没有任何效果。我再次浏览了讲课材料,但是找不到任何有帮助的内容,而且讨论板也很少受到学生提问的监视。
downcase!(* args)public
压缩str的内容,如果未进行任何更改,则返回nil。
由于.downcase!
方法的这种意外行为,如果单词已经全部为小写,则您将在此行中增加nil
的出现:
@highest_wf_words[word.downcase!] += 1
测试也失败了,因为@highest_wf_words.max_by {|word, count| count}
返回一个包含计数和一个单词的数组,而我们只想获取计数。
通过测试的简化的calculate_word_frequency
方法看起来像这样:
def calculate_word_frequency()
@highest_wf_words = Hash.new(0)
@content.split.each do |word|
# we don't have to check if the word existed before
# because we set 0 as default value in @highest_wf_words hash
# use .downcase instead of .downcase!
@highest_wf_words[word.downcase] += 1
# extract only the count, and then get the max
@highest_wf_count = @highest_wf_words.map {|word, count| count}.max
end
end
Nil:
零是downcase!
这将修改字符串就位,如果没有任何更改,则返回nil
。如果您说“这很奇怪”,那么您说得对(恕我直言)。
# just use the non destructive variant
word.downcase
排序:
sort_by
返回一个新对象(哈希,数组等),并且不修改该方法的接收者。您需要重新分配或使用sort_by!
unsorted = [3, 1, 2]
sorted = unsorted.sort
p unsorted # => [3, 1, 2]
p sorted # => [1, 2, 3]
unsorted.sort!
p unsorted # => [1, 2, 3]
错误字数:
一旦纠正了这两个错误,它看起来就会更好。请注意,该方法不会返回单个整数,而是返回包含单词和count的两个元素的数组,因此它应如下所示:["really", 6]
简化事物:
如果可以使用ruby 2.7,那么有方便的Enumerable#tally
方法!
%w(foo foo bar foo baz foo).tally
=> {"foo"=>4, "bar"=>1, "baz"=>1}
示例取自https://medium.com/@baweaver/ruby-2-7-enumerable-tally-a706a5fb11ea