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How to add an empty column to a dataframe?
...t; df = pd.DataFrame({"A": [1,2,3], "B": [2,3,4]})
>>> df
A B
0 1 2
1 2 3
2 3 4
>>> df["C"] = ""
>>> df["D"] = np.nan
>>> df
A B C D
0 1 2 NaN
1 2 3 NaN
2 3 4 NaN
...
Convert int to char in java
...ascii value 49 (one corresponding to '1')
If you want to convert a digit (0-9), you can add 48 to it and cast, or something like Character.forDigit(a, 10);.
If you want to convert an int as in ascii value, you can use Character.toChars(48) for example.
...
How to sort an array by a date property
... else if(sort_o1_after_o2) return 1;
else return 0;
});
Or more tersely:
array.sort(function(o1,o2){
return sort_o1_before_o2 ? -1 : sort_o1_after_o2 ? 1 : 0;
});
Generic, Powerful Answer
Define a custom non-enumerable sortBy function using a Schwartzian transform o...
open-ended function arguments with TypeScript
...ritten as,
function sum(...numbers: number[]) {
var aggregateNumber = 0;
for (var i = 0; i < numbers.length; i++)
aggregateNumber += numbers[i];
return aggregateNumber;
}
This will then type check correctly with
console.log(sum(1, 5, 10, 15, 20));
...
Does const mean thread-safe in C++11?
...ue...
This is what the Standard Language has to say on thread-safety:
[1.10/4]
Two expression evaluations conflict if one of them modifies a memory location (1.7) and the other one accesses or modifies the same memory location.
[1.10/21]
The execution of a program contains a data race if it contain...
How to convert byte array to Bitmap
...am blob = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 0 /* Ignored for PNGs */, blob);
byte[] bitmapdata = blob.toByteArray();
If bitmapdata is the byte array then getting Bitmap is done like this:
Bitmap bitmap = BitmapFactory.decodeByteArray(bitmapdata, 0, bitmapdata.length...
What do the return values of node.js process.memoryUsage() stand for?
...the Heap
heapUsed: Heap actually Used
Ref: http://apmblog.dynatrace.com/2015/11/04/understanding-garbage-collection-and-hunting-memory-leaks-in-node-js/
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SyntaxError: Use of const in strict mode
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Chrome: timeouts/interval suspended in background tabs?
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edited Apr 4 '18 at 20:59
GG.
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answered Ma...
How to send only one UDP packet with netcat?
...
205
If you are using bash, you might as well write
echo -n "hello" >/dev/udp/localhost/8000
a...