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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...
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...
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...
Why do we use arrays instead of other data structures?
...1000 compared to getting to P4.
Higher level data structures, such as hashtables, stacks and queues, all may use an array (or multiple arrays) internally, while Linked Lists and Binary Trees usually use nodes and pointers.
You might wonder why anyone would use a data structure that requires linear...
Calling virtual functions inside constructors
... way).
In C++ the Base class will build its version of the virtual method table prior to entering its own construction. At this point a call to the virtual method will end up calling the Base version of the method or producing a pure virtual method called in case it has no implementation at that le...
Parameterize an SQL IN clause
...
Yes, this is a table scan. Great for 10 rows, lousy for 100,000.
– Will Hartung
Dec 3 '08 at 16:48
17
...
Algorithm to detect corners of paper sheet in photo
...nes within a certain tolerance to those.
My grouping worked as a look up table, for each line outputted from the hough transform it would give a rho and theta pair. If these values were within, say 5% of a pair of values in the table, they were discarded, if they were outside that 5%, a new entry ...
How to convert char to int?
...appens.
A Char, is basically an integer, but with a pointer in the ASCII table. All characters have a corresponding integer value as you can clearly see when trying to parse it.
Pranay has clearly a different character set, thats why HIS code doesnt work.
the only way is
int val = '1' - '0';
...
How do I automatically update a timestamp in PostgreSQL
...
To populate the column during insert, use a DEFAULT value:
CREATE TABLE users (
id serial not null,
firstname varchar(100),
middlename varchar(100),
lastname varchar(100),
email varchar(200),
timestamp timestamp default current_timestamp
)
Note that the value for that column c...
Avoid line break between html elements
...
nobr is too unreliable, use tables
<table>
<tr>
<td> something </td>
<td> something </td>
</tr>
</table>
It all goes on the same line, everything is level with eachother,...