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What does $_ mean in PowerShell?
...
This is the variable for the current value in the pipe line, which is called $PSItem in Powershell 3 and newer.
1,2,3 | %{ write-host $_ }
or
1,2,3 | %{ write-host $PSItem }
For example in the above code the %{} block is called for every value in the array. The $_ or $PSItem variable ...
Passing parameters to a Bash function
...n_name {
command...
}
or
function_name () {
command...
}
To call a function with arguments:
function_name "$arg1" "$arg2"
The function refers to passed arguments by their position (not by name), that is $1, $2, and so forth. $0 is the name of the script itself.
Example:
function_n...
Representing graphs (data structure) in Python
...f._graph[node2].add(node1)
def remove(self, node):
""" Remove all references to node """
for n, cxns in self._graph.items(): # python3: items(); python2: iteritems()
try:
cxns.remove(node)
except KeyError:
pass
tr...
What's the difference between SortedList and SortedDictionary?
...<TKey,TValue> ? Are there any circumstances where you would specifically use one and not the other?
7 Answers
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C++ compiling on Windows and Linux: ifdef switch [duplicate]
... @MestreLion The Predef project has since been absorbed into Boost, but all the macros are still listed in the documentation here: boost.org/doc/libs/release/libs/predef/doc/html/index.html
– rubenvb
Mar 26 '16 at 12:43
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How can I filter a date of a DateTimeField in Django?
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Much better than all of the other answers here, thanks!
– Kin
Jan 6 '14 at 17:06
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How do I catch a numpy warning like it's an exception (not just for testing)?
...ng: divide by zero encountered in divide
array([0])
>>> np.seterr(all='print')
{'over': 'warn', 'divide': 'warn', 'invalid': 'warn', 'under': 'ignore'}
>>> np.array([1])/0 #'print' mode
Warning: divide by zero encountered in divide
array([0])
This means that the warning you see...
Replace multiple characters in one replace call
... just have to chain. However, you could add a prototype:
String.prototype.allReplace = function(obj) {
var retStr = this;
for (var x in obj) {
retStr = retStr.replace(new RegExp(x, 'g'), obj[x]);
}
return retStr;
};
console.log('aabbaabbcc'.allReplace({'a': 'h', 'b': 'o'}))...
Flatten nested dictionaries, compressing keys
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Basically the same way you would flatten a nested list, you just have to do the extra work for iterating the dict by key/value, creating new keys for your new dictionary and creating the dictionary at final step.
import collectio...
Mongoose, Select a specific field with find
... I think .select just is a filter to choose field after you get all of that, my recommendation is to use .find({}, 'name -_id')
– hong4rc
Mar 2 '19 at 16:15
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