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Select multiple columns in data.table by their numeric indices
...llowing all just work:
library(data.table)
dt <- data.table(a = 1, b = 2, c = 3)
# select single column by index
dt[, 2]
# b
# 1: 2
# select multiple columns by index
dt[, 2:3]
# b c
# 1: 2 3
# select single column by name
dt[, "a"]
# a
# 1: 1
# select multiple columns by name
dt[, ...
How to validate date with format “mm/dd/yyyy” in JavaScript?
...sValidDate(dateString)
{
// First check for the pattern
if(!/^\d{1,2}\/\d{1,2}\/\d{4}$/.test(dateString))
return false;
// Parse the date parts to integers
var parts = dateString.split("/");
var day = parseInt(parts[1], 10);
var month = parseInt(parts[0], 10);
va...
while (1) vs. while(True) — Why is there a difference (in python 2 bytecode)?
...e): pass and while(1): pass , but this is actually not the case in python2.7.
3 Answers
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Is it possible to GROUP BY multiple columns using MySQL?
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296
GROUP BY col1, col2, col3
...
Array extension to remove object by value
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As of Swift 2, this can be achieved with a protocol extension method.
removeObject() is defined as a method on all types conforming
to RangeReplaceableCollectionType (in particular on Array) if
the elements of the collection are Equatabl...
App Inventor 2 语音识别及文本朗读组件的使用 · App Inventor 2 中文网
...生成 App 鸿蒙 · 一套积木，多端原生打包！ 下载 AI2伴侣 · 安卓/鸿蒙/iOS aia 源码商店 中文社区 中文教育版 各版本对比 关于 关于我们 发布日志 服务条款 ...
How can I convert comma separated string into a List
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answered Feb 15 '12 at 20:59
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How to log request and response body with Retrofit-Android?
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92
I used setLogLevel(LogLevel.FULL).setLog(new AndroidLog("YOUR_LOG_TAG")), it helped me.
UPDATE. ...
How can I check if a key exists in a dictionary? [duplicate]
Let's say I have an associative array like so: {'key1': 22, 'key2': 42} .
3 Answers
3...