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validation custom message for rails 3
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edited Mar 4 '15 at 3:20
Andrew Hendrie
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an...
Python Charts库(Highcharts API的封装) - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...到类似下面的路径
'/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages'
然后进入目录下的chart目录,拷贝下图这些文件替换
1.If you want to plot a single series, you can use the name argument:
charts.plot(data, name='My list')
s...
T-SQL datetime rounded to nearest minute and nearest hours with using functions
...
declare @dt datetime
set @dt = '09-22-2007 15:07:38.850'
select dateadd(mi, datediff(mi, 0, @dt), 0)
select dateadd(hour, datediff(hour, 0, @dt), 0)
will return
2007-09-22 15:07:00.000
2007-09-22 15:00:00.000
The above just truncates the seconds and minutes, producing...
Return 0 if field is null in MySQL
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332
Use IFNULL:
IFNULL(expr1, 0)
From the documentation:
If expr1 is not NULL, IFNULL() ret...
How to swap keys and values in a hash
... (in essence, by letting you access keys through values):
{a: 1, b: 2, c: 3}.key(1)
=> :a
If you want to keep the inverted hash, then Hash#invert should work for most situations:
{a: 1, b: 2, c: 3}.invert
=> {1=>:a, 2=>:b, 3=>:c}
BUT...
If you have duplicate values, invert will...
`if __name__ == '__main__'` equivalent in Ruby
...
3 Answers
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How do Trigonometric functions work?
...ndard interval. For starters, you could reduce angles to be between 0 and 360 degrees. But by using a few identities, you realize you could get by with less. If you calculate sines and cosines for angles between 0 and 45 degrees, you can bootstrap your way to calculating all trig functions for all...
How to trace the path in a Breadth-First Search?
...
# graph is in adjacent list representation
graph = {
'1': ['2', '3', '4'],
'2': ['5', '6'],
'5': ['9', '10'],
'4': ['7', '8'],
'7': ['11', '12']
}
def bfs(graph, start, end):
# maintain a queue of paths
queue = []
# push the first path i...