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How to get a key in a JavaScript object by its value?
... associative array. Is there a simple function allowing me to get the key for a value, or do I have to iterate the object and find it out manually?
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NumPy or Pandas: Keeping array type as integer while having a NaN value
...e a preferred way to keep the data type of a numpy array fixed as int (or int64 or whatever), while still having an element inside listed as numpy.NaN ?
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Regex lookahead, lookbehind and atomic groups
...hese things in my regex body but I haven't got a clue what I can use them for.
Does somebody have examples so I can try to understand how they work?
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What does axis in pandas mean?
...0 along the rows (namely, index in pandas), and axis=1 along the columns. For added clarity, one may choose to specify axis='index' (instead of axis=0) or axis='columns' (instead of axis=1).
+------------+---------+--------+
| | A | B |
+------------+---------+---------
| ...
How to install Android SDK Build Tools on the command line?
...s not include the build tools in the list. They're in the "obsolete" category. To see all available downloads, use
android list sdk --all
And then to get one of the packages in that list from the command line, use:
android update sdk -u -a -t <package no.>
Where -u stands for --no-ui,...
How do you get the logical xor of two variables in Python?
How do you get the logical xor of two variables in Python?
24 Answers
24
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CSS Input Type Selectors - Possible to have an “or” or “not” syntax?
...visibility: hidden;
}
<p>If <code>:not()</code> is supported, you'll only see the checkbox.</p>
<ul>
<li>text: (<input type="text">)</li>
<li>password (<input type="password">)</li> ...
Combine two ActiveRecord::Relation objects
...rst_name_relation.merge(last_name_relation)
If you want to combine using OR (union), use or†:
first_name_relation.or(last_name_relation)
† Only in ActiveRecord 5+; for 4.2 install the where-or backport.
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JavaScript checking for null vs. undefined and difference between == and ===
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How do I check a variable if it's null or undefined...
Is the variable null:
if (a === null)
// or
if (a == null) // but see note below
...but note the latter will also be true if a is undefined.
Is it undefined:
if (typeof a === "undefined")
// or
if (a ==...
C# Class naming convention: Is it BaseClass or ClassBase or AbstractClass
...proach to naming base classes? Is it prefixing the type name with " Base " or " Abstract " or would we just suffix it with "Base"?
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