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MongoDB Aggregation: How to get total records count?
... felt when I finally achieved it LOL.
$result = $collection->aggregate(array(
array('$match' => $document),
array('$group' => array('_id' => '$book_id', 'date' => array('$max' => '$book_viewed'), 'views' => array('$sum' => 1))),
array('$sort' => $sort),
// get tot...
Very large matrices using Python and NumPy
...nd. Not bad for a Python-based solution!
Accessing the data as a NumPy recarray again is as simple as:
data = table[row_from:row_to]
The HDF library takes care of reading in the relevant chunks of data and converting to NumPy.
...
Modifying a subset of rows in a pandas dataframe
...c here, .loc is primarily label based, but may also be used with a boolean array.
So, what we are doing above is applying df.loc[row_index, column_index] by:
Exploiting the fact that loc can take a boolean array as a mask that tells pandas which subset of rows we want to change in row_index
Ex...
How do you get a string to a character array in JavaScript?
How do you convert a string to a character array in JavaScript?
13 Answers
13
...
get dictionary value by key
...
It's as simple as this:
String xmlfile = Data_Array["XML_File"];
Note that if the dictionary doesn't have a key that equals "XML_File", that code will throw an exception. If you want to check first, you can use TryGetValue like this:
string xmlfile;
if (!Data_Array.Tr...
How to hide one item in an Android Spinner
...item I think that you can implement your own adapter and set the index (or array list of indexes) that you want to hide.
public class CustomAdapter extends ArrayAdapter<String> {
private int hidingItemIndex;
public CustomAdapter(Context context, int textViewResourceId, String[] ob...
Create an empty object in JavaScript with {} or new Object()?
... '/img/picture.jpg',
width: 300,
height: 200
};
Arrays
For arrays, there's similarly almost no benefit to ever using new Array(); over []; - with one minor exception:
var emptyArray = new Array(100);
creates a 100 item long array with all slots containing undefined - w...
How to monitor the memory usage of Node.js?
...{ rss: 22269952, heapTotal: 11803648, heapUsed: 4530208 }
> var a = new Array(1e7); // Allocate memory for 10m items in an array
undefined
> process.memoryUsage(); // Memory after allocating so many items
{ rss: 102535168, heapTotal: 91823104, heapUsed: 85246576 }
> a = null; ...
Fastest way to flatten / un-flatten nested JSON objects
...tten = function(data) {
"use strict";
if (Object(data) !== data || Array.isArray(data))
return data;
var regex = /\.?([^.\[\]]+)|\[(\d+)\]/g,
resultholder = {};
for (var p in data) {
var cur = resultholder,
prop = "",
m;
while (...
Finding Variable Type in JavaScript
...tring("foo")
"object"
> typeof new Number(42)
"object"
The type of an array is still object. Here you really need the instanceof operator.
Update:
Another interesting way is to examine the output of Object.prototype.toString:
> Object.prototype.toString.call([1,2,3])
"[object Array]"
>...