红宝石查看CSV数据 [英] Ruby view csv data
问题描述
我是从CSV文件中得到一些数据（也如何在CSV选择前20条），例如：
I'm getting from csv file some data (also how to select first 20 in csv?), for example:
A B C
D E F
还方式：
def common_uploader
require 'csv'
arr = CSV.read("/#{Rails.public_path}/uploads_prices/"+params[:file], {:encoding => "CP1251:UTF-8", :col_sep => ";", :row_sep => :auto, :headers => :none})
@csv = []
@csv << arr
end
所以它是数组的数组...
但如何才能使我normaly查看它在HAML看法？
如何查看数组的数组？
我想是这样（也是每个文件我已经列数不同）：
观点：
so it is array of arrays... But how can i view it normaly in haml view? How can i view array of arrays? i tried something like (also in each file i have different count of columns): view:
= @csv.first.each do |a|
= a[:1]
请帮我查看CSV数据。
Help me please to view csv data.
推荐答案
有几种方法可以读取记录了一组号码，你需要选择一种基于数据源的预期大小来使用。
There are several ways you can read a set number of records, and you need to pick which to use based on the anticipated size of your data source.
用CSV文件启动：
A1,A2,A3
B1,B2,B3
C1,C2,C3
D1,D2,D3
E1,E2,E3
F1,F2,F3
读取的记录固定数量将是其中一个最简单的方法：
The simplest ways to read a fixed number of records would be one of these:
require 'csv'
array = CSV.read('test.csv')[0, 2]
它返回两个子数组的数组：
Which returns an array of two sub-arrays:
[
[0] [
[0] "A1",
[1] "A2",
[2] "A3"
],
[1] [
[0] "B1",
[1] "B2",
[2] "B3"
]
]
另一种是：
File.new('test.csv').readlines[0, 2].map{ |l| CSV.parse(l).flatten }
哪个返回相同的结果，两个子阵列的阵列
Which returns the same result, an array of two sub-arrays:
[
[0] [
[0] "A1",
[1] "A2",
[2] "A3"
],
[1] [
[0] "B1",
[1] "B2",
[2] "B3"
]
]
这两个都很好，小的输入文件，但如果你正在阅读从一个大的输入文件的几行会出现问题。他们将迫使Ruby来读取整个文件到内存中，并创建割掉你想要的记录数之前的中间阵列。我在哪里工作没什么让我们获得技嘉的文件大小，所以抓住这些文件的一小部分会使得Ruby和制做工作，建立中间数组，然后把它扔了大量资金。
Both of these are fine for small input files, but will have problems if you are reading a few lines from a big input file. They will force Ruby to read the entire file into memory and create an intermediate array before slicing off the number of records you want. Where I work it's nothing for us to get gigabyte file sizes, so grabbing a small section of those files would make Ruby and the system do an inordinate amount of work building the intermediate array then throwing it away.
您都关闭为只读的记录所需的最小数目更好。有时不拘一格读数之前要跳过;这表明理念，以处理一起的EOFError 如果输入文件的EOF被意外地遇到了：
You are better off to only read the minimum number of records needed. Sometimes lines need to be skipped before reading; This demonstrates that idea, along with handling EOFError if the input file's EOF is encountered unexpectedly:
File.open('test.csv') do |fi|
array = []
begin
5.times { fi.readline }
2.times.each{ array += CSV.parse(fi.readline) }
rescue EOFError
end
end
替换 5 用的记录数量跳过，而 2 与阅读次数。对于这个例子我特意读出该文件的末尾，以显示如何跳过线，读了一些，然后清洁处理EOF情况。
Replace 5 with the number of records to skip, and 2 with the number to read. For that example I deliberately read off the end of the file to show how to skip lines, read some and then handle the EOF situation cleanly.
中的数据是这样的：
[
[0] [
[0] "F1",
[1] "F2",
[2] "F3"
]
]
由于我使用 File.open 与块，文件将被自动块存在后关闭，避免留下一个开放的文件句柄游逛。
Because I'm using File.open with a block, the file is closed automatically after the block exists, avoiding leaving an open filehandle hanging around.
你的问题的HAML输出部分没有很好地在所有定义的，但是这是一种方式输出的数据：
The HAML output section of your question isn't well defined at all, but this is one way to output the data:
array = []
File.open('test.csv') do |fi|
begin
0.times { fi.readline }
2.times.each{ array += CSV.parse(fi.readline) }
rescue EOFError
end
end
require 'haml'
engine = Haml::Engine.new(<<EOT)
%html
%body
%table
- array.each do |r|
%tr
- r.each do |c|
%td= c
EOT
puts engine.render(Object.new, :array => array)
这将导致这个输出一个简单的HTML表格：</ P>
Which results in this output of a simple HTML table:
<html>
<body>
<table>
<tr>
<td>A1</td>
<td>A2</td>
<td>A3</td>
</tr>
<tr>
<td>B1</td>
<td>B2</td>
<td>B3</td>
</tr>
</table>
</body>
</html>
编辑：
和我的测试文件：dl.dropbox.com/u/59666091/qnt_small.csv我希望看到在这个浏览器7列（通过HAML视图）
and my test file: dl.dropbox.com/u/59666091/qnt_small.csv i want to see this 7 columns in browser (via haml view)
使用这个作为我的测试数据：
Using this as my test data:
a1,a2,a3,a4,a5,a6,a7
b1,b2,b3,b4,b5,b6,b7
c1,c2,c3,c4,c5,c6,c7
d1,d2,d3,d4,d5,d6,d7
e1,e2,e3,e4,e5,e6,e7
这code：
require 'csv'
array = []
File.open('test.csv') do |fi|
begin
0.times { fi.readline }
2.times.each{ array += CSV.parse(fi.readline) }
rescue EOFError
end
end
require 'haml'
engine = Haml::Engine.new(<<EOT)
%html
%body
%table
- array.each do |r|
%tr
- r.each do |c|
%td= c
EOT
puts engine.render(Object.new, :array => array)
我得到这样的输出：
I get this output:
<html>
<body>
<table>
<tr>
<td>a1</td>
<td>a2</td>
<td>a3</td>
<td>a4</td>
<td>a5</td>
<td>a6</td>
<td>a7</td>
</tr>
<tr>
<td>b1</td>
<td>b2</td>
<td>b3</td>
<td>b4</td>
<td>b5</td>
<td>b6</td>
<td>b7</td>
</tr>
</table>
</body>
</html>
我做了一个小的改动，以移动阵列之外 File.open 块，没有别的不同。
I made a minor change to move array outside the File.open block, nothing else is different.
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