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Replacing Pandas or Numpy Nan with a None to use with MysqlDB
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203
@bogatron has it right, you can use where, it's worth noting that you can do this natively in ...
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb
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22 Answers
22
Active
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Remove an item from a dictionary when its key is unknown
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92
Be aware that you're currently testing for object identity (is only returns True if both operand...
Retrieving Android API version programmatically
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edited Jan 28 '17 at 19:30
Siarhei
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Explain the encapsulated anonymous function syntax
...ve a function expression without a name defined:
(function () {
alert(2 + 2);
}());
Or named function expression:
(function foo() {
alert(2 + 2);
}());
The Parentheses (formally called the Grouping Operator) can surround only expressions, and a function expression is evaluated.
The tw...
How to replace a hash key with another key
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720
hash[:new_key] = hash.delete :old_key
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How does PHP 'foreach' actually work?
...function iterate($arr) {
foreach ($arr as $v) {}
}
$outerArr = [0, 1, 2, 3, 4];
iterate($outerArr);
Here, $arr will be duplicated to prevent IAP changes on $arr from leaking to $outerArr. In terms of the conditions above, the array is not a reference (is_ref=0) and is used in two places (refc...
MySQL Great Circle Distance (Haversine formula)
...& Google Maps:
Here's the SQL statement that will find the closest 20 locations that are within a radius of 25 miles to the 37, -122 coordinate. It calculates the distance based on the latitude/longitude of that row and the target latitude/longitude, and then asks for only rows where the dis...
Turning multi-line string into single comma-separated
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You can use awk and sed:
awk -vORS=, '{ print $2 }' file.txt | sed 's/,$/\n/'
Or if you want to use a pipe:
echo "data" | awk -vORS=, '{ print $2 }' | sed 's/,$/\n/'
To break it down:
awk is great at handling data broken down into fields
-vORS=, sets the "output re...
SQL WHERE condition is not equal to?
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You can do like this
DELETE FROM table WHERE id NOT IN ( 2 )
OR
DELETE FROM table WHERE id <> 2
As @Frank Schmitt noted, you might want to be careful about the NULL values too. If you want to delete everything which is not 2(including the NULLs) then add OR id IS NULL...