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How do I read any request header in PHP
...header fields, if the protocol used is HTTP. The HTTP header field name is converted to upper case, has all occurrences of - replaced with _ and has HTTP_ prepended to give the meta-variable name.
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Why do we need extern “C”{ #include } in C++?
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C and C++ are superficially similar, but each compiles into a very different set of code. When you include a header file with a C++ compiler, the compiler is expecting C++ code. If, however, it is a C header, then the compiler expects the data contained in the header file to be c...
Difference between reduce and foldLeft/fold in functional programming (particularly Scala and Scala
...top one level deep. We could chop up each chunk too. This is why summing integers in a list is O(log N) if given an infinite number of CPUs.
If you just look at the signatures there is no reason for reduce to exist because you can achieve everything you can with reduce with a foldLeft. The funct...
In c++ what does a tilde “~” before a function name signify?
...s method is called when the instance of your class is destroyed:
Stack<int> *stack= new Stack<int>;
//do something
delete stack; //<- destructor is called here;
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Is there a regular expression to detect a valid regular expression?
...n directly. (The (?1) and (?R) constructs.) The recursion would have to be converted to counting balanced groups:
^ # start of string
(?:
(?: [^?+*{}()[\]\\|]+ # literals and ^, $
| \\. # escaped charact...
Label encoding across multiple columns in scikit-learn
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We don't need a LabelEncoder.
You can convert the columns to categoricals and then get their codes. I used a dictionary comprehension below to apply this process to every column and wrap the result back into a dataframe of the same shape with identical indices a...
Combine multiple Collections into a single logical Collection?
...ow I could use guava iterables/iterators to generate a logical view on the internal collections without making temporary copies.
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Check if a string matches a regex in Bash script
...is in the correct format, it is best to parse it with date and ask date to convert the string to the correct format. If both strings are identical, you have a valid format and valid date.
if [[ "$datestr" == $(date -d "$datestr" "+%Y%m%d" 2>/dev/null) ]]; then
echo "Valid date"
else
e...
How to check whether an array is empty using PHP?
...er(): If no callback is supplied, all entries of array equal to FALSE (see converting to boolean) will be removed.
If you'd like to remove all NULL, FALSE and empty strings (''), but leave zero values (0), you can use strlen as a callback, e.g.:
$is_empty = array_filter($playerlist, 'strlen') == ...
How to access object attribute given string corresponding to name of that attribute
...me df1,and a variable x = 'df1' i.e. df1 as a string in var x. i want to print the shape of df like this, getattr(x, 'shape') or getattr('df1', 'shape'). I know this cannot be done with getattr, any other methods.
– ihightower
Feb 1 at 13:50
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