如何从使用Ruby的CSV中删除一行 [英] How to remove a row from a CSV with Ruby

问题描述

给定以下CSV文件，如何删除列foo中包含true一词的所有行？

Given the following CSV file, how would you remove all rows that contain the word 'true' in the column 'foo'?

Date,foo,bar
2014/10/31,true,derp
2014/10/31,false,derp

我有一个工作的解决方案，但它需要一个辅助CSV对象 csv_no_foo

@csv = CSV.read(@csvfile, headers: true) #http://bit.ly/1mSlqfA
@headers = CSV.open(@csvfile,'r', :headers => true).read.headers

# Make a new CSV
@csv_no_foo = CSV.new(@headers)

@csv.each do |row|
  # puts row[5]
  if row[@headersHash['foo']] == 'false'
    @csv_no_foo.add_row(row)
  else
    puts "not pushing row #{row}"
  end
end

，我只是从CSV中删除违规的行像这样：

Ideally, I would just remove the offending row from the CSV like so:

...
 if row[@headersHash['foo']] == 'false'
    @csv.delete(true) #Doesn't work
...

查看ruby文档，看起来像 row 类有一个 delete_if 函数。我对该函数需要的语法感到困惑。有没有办法删除该行而不创建新的csv对象？

Looking at the ruby documentation, it looks like the row class has a delete_if function. I'm confused on the syntax that that function requires. Is there a way to remove the row without making a new csv object?

http://ruby-doc.org/stdlib-1.9.2/libdoc/csv/rdoc/CSV/Row .html＃method-i-each

推荐答案

您应该可以使用CSV::Table#delete_if，但您需要使用 CSV： ：table 而不是 CSV :: read ，因为前者会为您提供一个CSV :: Table对象，而后者结果在数组数组。请注意，此设置也会将标题转换为符号。

You should be able to use CSV::Table#delete_if, but you need to use CSV::table instead of CSV::read, because the former will give you a CSV::Table object, whereas the latter results in an Array of Arrays. Be aware that this setting will also convert the headers to symbols.

table = CSV.table(@csvfile)

table.delete_if do |row|
  row[:foo] == 'true'
end

File.open(@csvfile, 'w') do |f|
  f.write(table.to_csv)
end

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