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Can dplyr package be used for conditional mutating?
...and the conditions (except for the default value of NA at the end) are mutually exclusive, as is the case in the question, then we can use an arithmetic expression such that each term is multiplied by the desired result using na_if at the end to replace 0 with NA.
df %>%
mutate(g = 2 * (a == 2 ...
Caching a jquery ajax response in javascript/browser
... return localCache.data[url];
},
set: function (url, cachedData, callback) {
localCache.remove(url);
localCache.data[url] = cachedData;
if ($.isFunction(callback)) callback(cachedData);
}
};
$(function () {
var url = '/echo/jsonp/';
$('#ajaxButton').clic...
Installing PG gem on OS X - failure to build native extension
It seems many others have had problems installing the pg gem. None of the solutions posed for others have worked for me.
1...
How do I reset a sequence in Oracle?
...
alter sequence serial restart start with 1;
This feature was officially added in 18c but is unofficially available since 12.1.
It is arguably safe to use this undocumented feature in 12.1. Even though the syntax is not included in the official documentation, it is generated by the Oracle pa...
What's wrong with nullable columns in composite primary keys?
...
Primary keys are for uniquely identifying rows. This is done by comparing all parts of a key to the input.
Per definition, NULL cannot be part of a successful comparison. Even a comparison to itself (NULL = NULL) will fail. This means a key containing NULL would not work.
Additonally, NULL is al...
Numpy first occurrence of value greater than existing value
... about why it gives the correct result despite the original intent not actually seeking a maximum, not why it is faster as I cannot claim to understand the inner details of argmax.
– askewchan
Oct 8 '14 at 14:24
...
How do I speed up the gwt compiler?
...
Let's start with the uncomfortable truth: GWT compiler performance is really lousy. You can use some hacks here and there, but you're not going to get significantly better performance.
A nice performance hack you can do is to compile for only specific browsers, by inserting the following line in...
Android: Difference between onInterceptTouchEvent and dispatchTouchEvent?
... are woefully inadequate about explaining this.
dispatchTouchEvent is actually defined on Activity, View and ViewGroup. Think of it as a controller which decides how to route the touch events.
For example, the simplest case is that of View.dispatchTouchEvent which will route the touch event to ei...
Is git good with binary files?
...aningful diffs, or merge binary files in any way that could make sense. So all merges, rebases or cherrypicks involving a change to a binary file will involve you making a manual conflict resolution on that binary file.
You need to decide whether the binary file changes are rare enough that you can...
Finding the source code for built-in Python functions?
...out what file a particular module or function is implemented in you can usually print the __file__ attribute. Alternatively, you may use the inspect module, see the section Retrieving Source Code in the documentation of inspect.
For built-in classes and methods this is not so straightforward since ...