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mmap() vs. reading blocks
...r random access, especially if your access patterns are sparse and unpredictable.
Memory maps allow you to keep using pages from the cache until you are done. This means that if you use a file heavily for a long period of time, then close it and reopen it, the pages will still be cached. With read...
Is std::unique_ptr required to know the full definition of T?
... compiler will tell you.
However, in case it is helpful to you, here is a table which documents several members of shared_ptr and unique_ptr with respect to completeness requirements. If the member requires a complete type, then entry has a "C", otherwise the table entry is filled with "I".
Comple...
NSDefaultRunLoopMode vs NSRunLoopCommonModes
... in different modes. A "run loop mode" is a convention used by the OS to establish some rules for when to deliver certain events or collect them to be delivered later.
Usually all run loops are set to the "default mode" which establishes a default way to manage input events. For example: as soon as...
Nearest neighbors in high-dimensional data?
...set of points in a high-dimensional space into a set of bins, i.e., a hash table [1][3]. But unlike traditional hashes, a locality-sensitive hash places nearby points into the same bin.
LSH has some huge advantages. First, it is simple. You just compute the hash for all points in your database, the...
How to move child element from one parent to another using jQuery [duplicate]
I am using the jQuery DataTables plugin. I would like to move the search box (.dataTables_filter) and number of records to display dropdown (.dataTables_length) from their parent element (.dataTables_wrapper) to another div on my page without losing any registered javascript behavior. For instance...
How to read data from a zip file without having to unzip the entire file
...can also extract to a file or other destinations).
Reading the zip file's table of contents is as easy as:
using (ZipFile zip = ZipFile.Read(ExistingZipFile))
{
foreach (ZipEntry e in zip)
{
if (header)
{
System.Console.WriteLine("Zipfile: {0}", zip.Name);
if ((zip.Comment ...
Likelihood of collision using most significant bits of a UUID in Java
...ou need uniqueness across many machines, you could have a central database table for allocating unique ids, or even batches of unique ids.
If you just need to have uniqueness in one app you can just have a counter (or a counter which starts from the currentTimeMillis()*1000 or nanoTime() depending...
Text size and different android screen sizes
...ve been deprecated since Android 3.2 in favor of the following:
Declaring Tablet Layouts for Android 3.2
For the first generation of tablets running Android 3.0, the proper
way to declare tablet layouts was to put them in a directory with the
xlarge configuration qualifier (for example, res...
Static extension methods [duplicate]
....Parse(..)
vs.
Helper.ParseBool(..);
Doesn't really bring much to the table...
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count the frequency that a value occurs in a dataframe column
... x 1 columns]
See the online docs: http://pandas.pydata.org/pandas-docs/stable/groupby.html
Also value_counts() as @DSM has commented, many ways to skin a cat here
In [38]:
df['a'].value_counts()
Out[38]:
b 3
a 2
s 2
dtype: int64
If you wanted to add frequency back to the original d...