Compare operation with collections - Create collections
1. Create List
DescriptionJDKguavags-collectionsCreate empty listnew ArrayList<>()Lists.newArrayList()FastList.newList()Create list from valuesArrays.asList("1", "2", "3")Lists.newArrayList("1", &...
Suppose we want to count how many counties are there in Texas:
var counties = dbContext.States.Single(s => s.Code == "tx").Counties.Count();
The query is correct, but inefficient. States.Single(…) loads a state from the database. Next, Counties loads all 254 counties with all of the...
Types of columns can be checked by .dtypes atrribute of DataFrames.
In [1]: df = pd.DataFrame({'A': [1, 2, 3], 'B': [1.0, 2.0, 3.0], 'C': [True, False, True]})
In [2]: df
Out[2]:
A B C
0 1 1.0 True
1 2 2.0 False
2 3 3.0 True
In [3]: df.dtypes
Out[3]:
A int64
...
astype() method changes the dtype of a Series and returns a new Series.
In [1]: df = pd.DataFrame({'A': [1, 2, 3], 'B': [1.0, 2.0, 3.0],
'C': ['1.1.2010', '2.1.2011', '3.1.2011'],
'D': ['1 days', '2 days', '3 days'],
...
select_dtypes method can be used to select columns based on dtype.
In [1]: df = pd.DataFrame({'A': [1, 2, 3], 'B': [1.0, 2.0, 3.0], 'C': ['a', 'b', 'c'],
'D': [True, False, True]})
In [2]: df
Out[2]:
A B C D
0 1 1.0 a True
1 2 2.0 b False
2...
get_dtype_counts method can be used to see a breakdown of dtypes.
In [1]: df = pd.DataFrame({'A': [1, 2, 3], 'B': [1.0, 2.0, 3.0], 'C': ['a', 'b', 'c'],
'D': [True, False, True]})
In [2]: df.get_dtype_counts()
Out[2]:
bool 1
float64 1
int64 1
obje...
This example shows how to create a prepared statement with an insert statement with parameters, set values to those parameters and then executing the statement.
Connection connection = ... // connection created earlier
try (PreparedStatement insert = connection.prepareStatement(
"i...
In PaaS sites such as Heroku, it is usual to receive the database information as a single URL environment variable, instead of several parameters (host, port, user, password...).
There is a module, dj_database_url which automatically extracts the DATABASE_URL environment variable to a Python dictio...
To connect to MySQL you need to use the MySQL Connector/J driver. You can download it from http://dev.mysql.com/downloads/connector/j/ or you can use Maven:
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version...
When you create a function in TypeScript you can specify the data type of the function's arguments and the data type for the return value
Example:
function sum(x: number, y: number): number {
return x + y;
}
Here the syntax x: number, y: number means that the function can accept two argum...
Example:
function hello(name: string): string {
return `Hello ${name}!`;
}
Here the syntax name: string means that the function can accept one name argument and this argument can only be string and (...): string { means that the return value can only be a string
Usage:
hello('StackOverfl...
You can start the mongo shell by running the following command inside your Meteor project:
meteor mongo
Please note: Starting the server-side database console only works while Meteor is running the application locally.
After that, you can list all collections by executing the following command...
TeX formulae can be inserted in the plot using the rc function
import matplotlib.pyplot as plt
plt.rc(usetex = True)
or accessing the rcParams:
import matplotlib.pyplot as plt
params = {'tex.usetex': True}
plt.rcParams.update(params)
TeX uses the backslash \ for commands and symbols, whic...
In order to include plots created with matplotlib in TeX documents, they should be saved as pdf or eps files. In this way, any text in the plot (including TeX formulae) is rendered as text in the final document.
import matplotlib.pyplot as plt
plt.rc(usetex=True)
x = range(0, 10)
y = [t**2 for t...
You can search Docker Hub for images by using the search command:
docker search <term>
For example:
$ docker search nginx
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
nginx Official build of Nginx. ...
public class MyObject{
public DateTime? TestDate { get; set; }
public Func<MyObject, bool> DateIsValid = myObject => myObject.TestDate.HasValue && myObject.TestDate > DateTime.Now;
public void DoSomething(){
//We can do this:
if(this.TestDate....
Dart has a robust async library, with Future, Stream, and more. However, sometimes you might run into an asynchronous API that uses callbacks instead of Futures. To bridge the gap between callbacks and Futures, Dart offers the Completer class. You can use a Completer to convert a callback into a Fut...
GNU gettext is an extension within PHP that must be included at the php.ini:
extension=php_gettext.dll #Windows
extension=gettext.so #Linux
The gettext functions implement an NLS (Native Language Support) API which can be used to internationalize your PHP applications.
Translating strings ...
The following example creates a canvas with 2 points and 1 line in between.
You will be able to move the point and the line around.
from kivy.app import App
from kivy.graphics import Ellipse, Line
from kivy.uix.boxlayout import BoxLayout
class CustomLayout(BoxLayout):
def __init__(se...
When defining a function, use {param1, param2, …} to specify named parameters:
void enableFlags({bool bold, bool hidden}) {
// ...
}
When calling a function, you can specify named parameters using paramName: value
enableFlags(bold: true, hidden: false);
