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Pass column name in data.table using variable [duplicate]
...] "b" "b" "b" "a" "a"
With a single column name, the result is a vector. If you want a data.table result, or several columns, use list form
temp <- quote(list(x, v))
DT[ , eval(temp)]
# x v
# 1: b 1.52566586
# 2: b 0.66057253
# 3: b -1.29654641
# 4: a -1.71998260
# 5: a 0.031599...
Maven dependency spring-web vs spring-webmvc
What is the difference between the following dependencies?
2 Answers
2
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Can a relative sitemap url be used in a robots.txt?
...l documentation on sitemaps.org it needs to be a full URL:
You can specify the location of the Sitemap using a robots.txt file. To do this, simply add the following line including the full URL to the sitemap:
Sitemap: http://www.example.com/sitemap.xml
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DTO and DAO concepts and MVC [closed]
...just the part responsible for data retrieval.
As for the second question, if you have a small application it is completely OK, however, if you want to follow the MVC pattern it would be better to have a separate controller, which would contain the business logic for your frame in a separate class a...
Intellij code formatting, Java annotations on new lines
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If you are still not seeing the format you want, experiment with changing the other options (above and below the highlighted box) from Chop down if long to Wrap always.
– vegemite4me
Oct...
mongod, mac os x - rlimits warning [closed]
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on mac, you probably using mongodb for development purpose. If yes, then you can ignore this.
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How can I get the current date and time in the terminal and set a custom command in the terminal for
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if you are looking for sometting like YYYYMMDDHHMMSS, 20160804020100 use the command this way: date +%Y%m%d%H%M%S. It servers most purposes like file backup, or log filtering.
– computingfreak
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App Inventor 2 复制屏幕功能，界面设计更便捷，避免误删组件 · App Inventor 2 中文网
...鼠标移动时拖动元素 document.onmousemove = function(e) { if (!isDragging) return; element.style.left = (e.clientX - offsetX) + 'px'; element.style.top = (e.clientY - offsetY) + 'px'; }; // 鼠标释放时停止拖动 document.onmouseup = function(...
分享几个App Inventor 2"隐藏"的非常的实用的小技巧 · App Inventor 2 中文网
...鼠标移动时拖动元素 document.onmousemove = function(e) { if (!isDragging) return; element.style.left = (e.clientX - offsetX) + 'px'; element.style.top = (e.clientY - offsetY) + 'px'; }; // 鼠标释放时停止拖动 document.onmouseup = function(...
编程基础与事件状态 03：计时器刷新，截止时刻计时 · App Inventor 2 中文网
...lobal 状态 = "待开始"
global 任务 = ""
when 计时器1.Timer() {
if 状态 = "运行" {
剩余 = max(0, ceil((截止 - 计时器1.SystemTime()) / 1000))
if 剩余 = 0 {
状态 = "完成"
计时器1.TimerEnabled = false
}
标签_剩余.Text = join(剩余, " 秒")
标签_状态.Text = join(...