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Group by multiple columns in dplyr, using string vector input
...cumentation here). This lets you use the same functions you would use with select, like so:
data = data.frame(
asihckhdoydkhxiydfgfTgdsx = sample(LETTERS[1:3], 100, replace=TRUE),
a30mvxigxkghc5cdsvxvyv0ja = sample(LETTERS[1:3], 100, replace=TRUE),
value = rnorm(100)
)
# get the column...
Where does mongodb stand in the CAP theorem?
...
MongoDB selects Consistency over Availability whenever there is a Partition. What it means is that when there's a partition(P) it chooses Consistency(C) over Availability(A).
To understand this, Let's understand how MongoDB does rep...
When would you use delegates in C#? [closed]
...ionString = psConnectionString;
}
public void UseReader( string psSELECT, DataReaderUser readerUser )
{
using ( SqlConnection connection = new SqlConnection( _connectionString ) )
try
{
SqlCommand command = new SqlCommand( psSELECT, connection );
...
How do I return rows with a specific value first?
...to treat boolean expressions as having a numeric value, then you can use:
SELECT *
FROM `Users`
ORDER BY (`city` = 'New York') DESC, `city`
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How to get all files under a specific directory in MATLAB?
...d the ability to apply a validation function to each file, allowing you to select them based on criteria other than just their names (i.e. file size, content, creation date, etc.).
NOTE: In newer versions of MATLAB (R2016b and later), the dir function has recursive search capabilities! So you can...
UINavigationController without navigation bar?
...
In Xcode 4.3.2:
Select the navigation controller in the storyboard
Select the Attributes Inspector in the (right) Utilities panel
Under the Navigation Controller category you have two check boxes:
[] Shows Navigation Bar
[] Shows Toolbar
...
Reading an image file into bitmap from sdcard, why am I getting a NullPointerException?
...g.ARGB_8888;
Bitmap bitmap = BitmapFactory.decodeFile(photoPath, options);
selected_photo.setImageBitmap(bitmap);
or
http://mihaifonoage.blogspot.com/2009/09/displaying-images-from-sd-card-in.html
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RecyclerView onClick
... the ViewHolder itself contains all information in regards to what data is selected when the element itself is clicked, then the only responsibility of the container is the display of N elements, rather than that of handling the selection of a specific i-th element out of the N elements. The ListVie...
Access Denied for User 'root'@'localhost' (using password: YES) - No Privileges?
...th socket, which means you just connect with sudo mysql. If you run sql :
SELECT user,authentication_string,plugin,host FROM mysql.user;
then you will see it :
+------------------+-------------------------------------------+-----------------------+-----------+
| user | authentication...
What is the difference between svg's x and dx attribute?
...}
</style>
<script>
dataset = d3.range(50,500,50);
svg = d3.select("body").append("svg");
svg.attr('width',500).attr('height', 500);
svg.append("line").attr('x1', 0).attr('x2', 500).attr('y1', 100).attr('y2', 100);
svg.append("line").attr('x1', 0).attr('x2', 500).attr('y1', 200).attr...