如何替換CSV標頭

Question

如果在ruby中使用'csv'庫，如何替換標頭而不重新讀取文件？

foo.csv

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

使用CSV ::表because of this answer

這裏是一個可行的解決方案，但是它需要寫入和讀取文件的兩倍。

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 

如何在不從磁盤讀取兩次的情況下修改標題？

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

更新
對於那些好奇，here is the unabridged code。爲了使用像delete_if()之類的東西，必須使用CSV.table（）函數導入CSV。

也許可以通過將csv錶轉換爲數組數組來改變頭，但是我不知道該怎麼做。

Answer 1

給出一個test.csv文件，其內容是這樣的：

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

您可以使用此替換標題行：

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，如果你寧願保留原始二維數組：

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"]]