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Bash if [ false ] ; returns true
Been learning bash this week and ran into a snag.
6 Answers
6
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PHP's array_map including keys
...ond_key" => "second_value");
array_walk($test_array, function(&$a, $b) { $a = "$b loves $a"; });
var_dump($test_array);
// array(2) {
// ["first_key"]=>
// string(27) "first_key loves first_value"
// ["second_key"]=>
// string(29) "second_key loves second_value"
// }
It does ...
Replacing NAs with latest non-NA value
In a data.frame (or data.table), I would like to "fill forward" NAs with the closest previous non-NA value. A simple example, using vectors (instead of a data.frame ) is the following:
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How do I use $rootScope in Angular to store variables?
How do I use $rootScope to store variables in a controller I want to later access in another controller? For example:
8 A...
Why is the minimalist, example Haskell quicksort not a “true” quicksort?
Haskell's website introduces a very attractive 5-line quicksort function , as seen below.
11 Answers
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How to select all records from one table that do not exist in another table?
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SELECT t1.name
FROM table1 t1
LEFT JOIN table2 t2 ON t2.name = t1.name
WHERE t2.name IS NULL
Q: What is happening here?
A: Conceptually, we select all rows from table1 and for each row we attempt to find a row in table2 with the same value for ...
How to pass a function as a parameter in Java? [duplicate]
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Java 8 and above
Using Java 8+ lambda expressions, if you have a class or interface with only a single abstract method (sometimes called a SAM type), for example:
public interface MyInterface {
String doSomething(int param1, String...
How does comparison operator works with null int?
I am starting to learn nullable types and ran into following behavior.
4 Answers
4
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How do you delete a column by name in data.table?
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Any of the following will remove column foo from the data.table df3:
# Method 1 (and preferred as it takes 0.00s even on a 20GB data.table)
df3[,foo:=NULL]
df3[, c("foo","bar"):=NULL] # remove two columns
myVar = "foo"
df3[, (myVar):=NULL] # lookup myVar contents
# Method 2a --...
Possible to iterate backwards through a foreach?
I know I could use a for statement and achieve the same effect, but can I loop backwards through a foreach loop in C#?
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