大约有 42,000 项符合查询结果（耗时：0.0463秒） [XML]
What is the best way to implement nested dictionaries?
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183
What is the best way to implement nested dictionaries in Python?
This is a bad idea, don't do ...
How to convert a boolean array to an int array
...gt;> x
array([ True, False, True], dtype=bool)
>>> x + [1, 2, 3]
array([2, 2, 4])
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Changing git commit message after push (given that no one pulled from remote)
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edited May 23 '17 at 10:31
Community♦
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answered Jan 24 '12 at 2:02
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What exactly is Arel in Rails 3.0?
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What exactly is Arel in Rails 3.0?
It's an object model for an algebra of relational query operators.
I understand that it is a replacement for ActiveRecord
No, it isn't. It's a replacement for hand-crafting SQL queries in strings. It is a common query...
How do you manually execute SQL commands in Ruby On Rails using NuoDB
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edited Jan 23 '19 at 10:24
Jan Klimo
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Update MongoDB field using value of another field
..."name": { "$concat": ["$firstName", " ", "$lastName"]}}}
]
)
MongoDB 3.4+
In 3.4+ you can use $addFields and the $out aggregation pipeline operators.
db.collection.aggregate(
[
{ "$addFields": {
"name": { "$concat": [ "$firstName", " ", "$lastName" ] }
}},
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PyCharm shows unresolved references error for valid code
...Dmitry Trofimov
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3
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App Inventor 2开发计步器与定位器 - App Inventor 2 中文网 - 清泛IT论坛，有思想、有深度
...2.了解数据持久化，掌握数据存储等功能的实现；
3.通过编程实践，感受和体验利用手机自身硬件开发实用的手机应用程序。 【项目范例】
1. 情境
现在的手机都已经具有计步器及位置传感器等各种硬件传感...
Replace tabs with spaces in vim
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393
IIRC, something like:
set tabstop=2 shiftwidth=2 expandtab
should do the trick. If you alre...
Fastest way to replace NAs in a large data.table
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system.time(a_gdata = f_gdata(dt1))
user system elapsed
18.805 12.301 134.985
system.time(a_andrie = f_andrie(dt1))
Error: cannot allocate vector of size 305.2 Mb
Timing stopped at: 14.541 7.764 68.285
system.time(f_dowle(dt1))
user system elapsed
7.452 4.144 19.590 # EDIT h...