Question

如果使用＆＃39; csv＆＃39; ruby中的库，如何在不重新读取文件的情况下替换标题？

foo.csv

'date','foo',bar'
1,2,3
4,5,6

使用CSV ::表格because of this answer

这是一个有效的解决方案，但它需要两次写入和读取文件。

require 'csv'
@csv = CSV.table('foo.csv')

# Perform additional operations, like remove specific pieces of information. 

# Save fixed csv to a file (with incorrect headers)
File.open('bar.csv','w') do |f|
  f.write(@csv.to_csv)
end

# New headers
new_keywords = ['dur','hur', 'whur']

# Reopen the file, replace the headers, and print it out for debugging
# Not sure how to replace the headers of a CSV::Table object, however I *can* replace the headers of an array of arrays (hence the file.open)
lines = File.readlines('bar.csv')
lines.shift
lines.unshift(new_keywords.join(',') + "\n")
puts lines.join('')

# TODO: re-save file to disk

如何在不读取磁盘两次的情况下修改标头？

'dur','hur','whur'
1,x,3
4,5,x

更新
对于那些好奇的人，here is the unabridged code。要使用delete_if()之类的内容，必须使用CSV.table（）函数导入CSV。

也许可以通过将csv表转换为数组数组来更改标题，但是我不知道该怎么做。

Answer 1

给定一个test.csv文件，其内容如下所示：

id,name,age
1,jack,8
2,jill,9

您可以使用以下方法替换标题行：

require 'csv'

array_of_arrays = CSV.read('test.csv')

p array_of_arrays # => [["id", "name", "age"],
                  # =>  ["1", "jack", "26"],
                  # =>  ["2", "jill", "27"]]    

new_keywords = ['dur','hur','whur']

array_of_arrays[0] = new_keywords

p array_of_arrays # => [["dur", "hur", "whur"],
                  # =>  ["1", " jack", " 26"],
                  # =>  ["2", " jill", " 27"]]

或者，如果您更愿意保留原始的二维数组：

new_array = Array.new(array_of_arrays)
new_array[0] = new_keywords

p new_array # => [["dur", "hur", "whur"],
            # =>  ["1", " jack", " 26"],
            # =>  ["2", " jill", " 27"]]

p array_of_arrays # => [["id", "name", "age"],
                  # =>  ["1", "jack", "26"],
                  # =>  ["2", "jill", "27"]]

如何替换CSV标头

1 个答案: