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How to “test” NoneType in python?
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It can also be done with isinstance as per Alex Hall's answer :
>>> NoneType = type(None)
>>> x = None
>>> type(x) == NoneType
True
>>> isinstance(x, NoneType)
True
isinstance is also intuitive but there is the complication that it requires the line
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Declare a constant array
...must be constant expressions, evaluatable by the compiler. For instance, 1<<3 is a constant expression, while math.Sin(math.Pi/4) is not because the function call to math.Sin needs to happen at run time.
Slices and arrays are always evaluated during runtime:
var TestSlice = []float32 {.03, .0...
Convert a string to regular expression ruby
...ere you need the initial string to be in single quotes (refer this page)
>> str = '[\w\s]+'
=> "[\\w\\s]+"
>> Regexp.new str
=> /[\w\s]+/
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What is a race condition?
When writing multithreaded applications, one of the most common problems experienced is race conditions.
18 Answers
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Calculate number of hours between 2 dates in PHP
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// The diff-methods returns a new DateInterval-object...
$diff = $date2->diff($date1);
// Call the format method on the DateInterval-object
echo $diff->format('%a Day and %h hours');
The DateInterval-object, which is returned also provides other methods than format. If you want the result...
How to filter Pandas dataframe using 'in' and 'not in' like in SQL
...IN": ~something.isin(somewhere)
As a worked example:
import pandas as pd
>>> df
country
0 US
1 UK
2 Germany
3 China
>>> countries_to_keep
['UK', 'China']
>>> df.country.isin(countries_to_keep)
0 False
1 True
2 False
3 True
Name: country...
Is there an ignore command for git like there is for svn?
...nore all .svn folders, run this from the root of the project:
echo .svn/ >> .gitignore
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What is the difference between static func and class func in Swift?
...be clearer, I make an example here,
class ClassA {
class func func1() -> String {
return "func1"
}
static func func2() -> String {
return "func2"
}
/* same as above
final class func func2() -> String {
return "func2"
}
*/
}
static func is same as final class...
Java string to date conversion
...string);
mydate.setTime(thedate);
//breakdown
System.out.println("mydate -> "+mydate);
System.out.println("year -> "+mydate.get(Calendar.YEAR));
System.out.println("month -> "+mydate.get(Calendar.MONTH));
System.out.println("dom -> "+mydate.get(Calendar.DAY_OF_MONTH));
System.out.p...
moment.js - UTC gives wrong date
...me examples to illustrate it (my local time offset is UTC+3 during DST):
>>> moment('07-18-2013', 'MM-DD-YYYY').utc().format("YYYY-MM-DD HH:mm")
"2013-07-17 21:00"
>>> moment('07-18-2013 12:00', 'MM-DD-YYYY HH:mm').utc().format("YYYY-MM-DD HH:mm")
"2013-07-18 09:00"
>>> D...