为什么散列的内容无法保存到CSV文件中？ [英] Why is the hashed content not getting saved into the CSV file?

问题描述

我在CSV文件中有一个列， Original.csv ，其中有一堆用户ID，其中一些重复，如下所示：

  UDID 
 d0155049772de9 
 8b57d8c7f1e5a31e4adaef5fe6c52df1ada7fcd5 
 8b57d8c7f1e5a31e4adaef5fe6c52df1ada7fcd5 
 465088425ceb38c62bf8d1d9cc33bcfab4fe4293 
 3eabe40461773086 
 3eabe40461773086 
 e24356719f086021 
 212b5b0415560be3 
 1c046451a3761ef51fbf52759748f66c98b02313 
  

我想要处理它们MATLAB以后，所以我想哈希和转换成整数，并将它们存储在一个新的文件， New.csv 。这是我的代码：

  require'csv'
 
 udids = [] 
 id = [] 
 
 CSV.foreach（'Original.csv'，：headers => true）.map do | row | 
 udids<< row [0] 
 end 
 
 udids = udids.uniq 
 arrayHash = [] 
 
 for i in 0..udids.size-1 
 arrayHash<< udids 
 arrayHash<< i 
 end 
 
 hash = Hash [arrayHash.each_slice（2）.to_a] 
 $ b b id = hash.values_at * udids 
 
 for i in 0..id.size-1 
 logfile = File.new（'New.csv'，w）
 logfile.print（＃{id [i]} \\\
）
 logfile.close 
 end 
  

由于某些原因我不能弄清楚，运行代码后， New.csv 文件是空的。问题是什么？

编辑：这个程序的哈希值比简单比较和检查用户ID是否重复之前执行得更快？像这样：

  CSV.open（'New.csv'，wb）do | csv | 
 CSV.foreach（'Original.csv'，：headers => true）.map do | row | 
 unless udids.include？（row [0]）
 udids<< row [0] 
 end 
 csv< udids.index（row [56]）+ 1 
 end 
 end 
  / pre> 
 
 
在这两种情况下，你能说为什么一个会比另一个更快？ 
解决方案
没有对您的完整代码进行深入研究：
 
 
 
使用
  for in in 0..id.size-1 
 logfile = File.new（'New.csv'，w）
 logfile.print（＃{id [i]} \\\
）
 logfile.close 
 end 
  
您打开文件 id.size-1 次，写一行并关闭它。 
 
 
 
看起来你想要这样的
  File.open（'New.csv'，w）do | logfile | ＃打开文件
 id.each {| one_id | #loop on all ids 
 logfile.print（＃{one_id} \\\
）#write一行中的一个id 
} 
 end＃关闭文件
  
 
I have a column in a CSV file, Original.csv, which has a bunch of user IDs, some of which repeat, like following: 
udid
d0155049772de9
8b57d8c7f1e5a31e4adaef5fe6c52df1ada7fcd5
8b57d8c7f1e5a31e4adaef5fe6c52df1ada7fcd5
465088425ceb38c62bf8d1d9cc33bcfab4fe4293
3eabe40461773086
3eabe40461773086
e24356719f086021
212b5b0415560be3
1c046451a3761ef51fbf52759748f66c98b02313
I want to process them in MATLAB later, so I wanted to hash and convert them into integers and store them in a new file, New.csv. This is my code:
require 'csv'

udids = []
id=[]

CSV.foreach('Original.csv', :headers=>true).map do |row|
    udids << row[0]
end

udids=udids.uniq
arrayHash=[]

for i in 0..udids.size-1
    arrayHash<<udids
    arrayHash<<i
end

hash = Hash[arrayHash.each_slice(2).to_a]

id=hash.values_at *udids

for i in 0..id.size-1
    logfile = File.new('New.csv',"w")
    logfile.print("#{id[i]}\n")
    logfile.close
end
Due to some reason I haven't able to figure out, the New.csv file is empty after running the code. What's the issue?

Edit: Is hashing for this program going to perform faster than simply comparing and checking if a user ID has been repeated before? Something like this:
CSV.open('New.csv', "wb") do |csv|
   CSV.foreach('Original.csv', :headers=>true).map do |row|
     unless udids.include?(row[0])
      udids << row[0]
    end
    csv<<udids.index(row[56]) + 1
    end
end
In either case, could you please say why one would perform faster over the other? My CSV has 60 million records, if that matters.
解决方案
Without a deeper look on your complete code:

With 
for i in 0..id.size-1
    logfile = File.new('New.csv',"w")
    logfile.print("#{id[i]}\n")
    logfile.close
end
You open the file id.size-1 times, write one line and close it. In the end you have the file with the last entry.

It seems you want something like this
    File.open('New.csv',"w") do |logfile| #Open the file
      id.each{|one_id|                #loop on all ids
        logfile.print("#{one_id}\n")  #write one id in line
      }
    end       #Close the file


                        
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