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How to select the row with the maximum value in each group
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A dplyr solution:
library(dplyr)
ID <- c(1,1,1,2,2,2,2,3,3)
Value <- c(2,3,5,2,5,8,17,3,5)
Event <- c(1,1,2,1,2,1,2,2,2)
group <- data.frame(Subject=ID, pt=Value, Event=Event)
group %>%
group_by(Subject) %>%
summarize(max.pt = max(...
sql primary key and index
Say I have an ID row (int) in a database set as the primary key. If I query off the ID often do I also need to index it? Or does it being a primary key mean it's already indexed?
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How to iterate over array of objects in Handlebars?
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You can pass this to each block. See here: http://jsfiddle.net/yR7TZ/1/
{{#each this}}
<div class="row"></div>
{{/each}}
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How to rename items in values() in Django?
... -1 because .values(supports__through_tables) and this hack doesn't (incidentally probably the most obvious use case for wanting to rename the ValuesQuerySet dict keys)
– wim
Aug 21 '14 at 13:12
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PHP Redirect with POST data
I did some research on this topic, and there are some experts who have said that it is not possible , so I would like to ask for an alternative solution.
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MongoDB副本集详解 优于以往的主从模式 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...照一些属性来判断谁应该胜出。这个属性可以是一个静态ID，也可以是更新的度量像最近一次事务ID（最新的节点会胜出）
他的选举过程大致如下：
? 得到每个服务器节点的最后操作时间戳。每个mongodb都有oplog机制会记录本机...
Setting CSS pseudo-class rules from JavaScript
... can do it by altering the stylesheet, for example by adding the rule:
#elid:hover { background: red; }
assuming each element you want to affect has a unique ID to allow it to be selected.
In theory the document you want is http://www.w3.org/TR/DOM-Level-2-Style/Overview.html which means you can...
How to make all Objects in AWS S3 bucket public by default?
...Add Statement"
Then select "Generate Policy"
Copy the text example:
{
"Id": "Policy1397632521960",
"Statement": [
{
"Sid": "Stmt1397633323327",
"Action": [
"s3:GetObject"
],
"Effect": "Allow",
"Resource": "arn:aws:s3:::bucketnm/*",
"Principal": {...
Deep copy of a dict in python
... Is there any difference in Python 3.2 and 2.7 codes? They seem identical to me. If so, would be better a single block of code and a statement "Works for both Python 3 and 2"
– MestreLion
Jun 7 '14 at 3:59
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How to get nice formatting in the Rails console
...rom ruby-docs
In older Ruby versions, ie. <= 1.9, Syck is still provided, however it
was completely removed with the release of Ruby 2.0.0.
For rails 4/ruby 2 you could use just
puts object.to_yaml
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