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Use of ~ (tilde) in R programming Language
...".
The myFormula <- part of that line stores the formula in an object called myFormula so you can use it in other parts of your R code.
Other common uses of formula objects in R
The lattice package uses them to specify the variables to plot.
The ggplot2 package uses them to specify panels fo...
DateTime2 vs DateTime in SQL Server
...e seconds precision.
datetimeoffset provides time zone
support for globally deployed
applications.
datetime2 has larger date range, a larger default fractional precision, and optional user-specified precision. Also depending on the user-specified precision it may use less storage.
...
File being used by another process after using File.Create()
...pens a FileStream on the file. So your file is already open. You don't really need the file.Create method at all:
string filePath = @"c:\somefilename.txt";
using (StreamWriter sw = new StreamWriter(filePath, true))
{
//write to the file
}
The boolean in the StreamWriter constructor will cau...
How do I set/unset a cookie with jQuery?
... do:
$.cookie("test", 1);
To delete:
$.removeCookie("test");
Additionally, to set a timeout of a certain number of days (10 here) on the cookie:
$.cookie("test", 1, { expires : 10 });
If the expires option is omitted, then the cookie becomes a session cookie and is deleted when the browser ...
What is the Python 3 equivalent of “python -m SimpleHTTPServer”
...as been merged into http.server in Python 3.0. The 2to3 tool will automatically adapt imports when converting your sources to 3.0.
So, your command is python -m http.server, or depending on your installation, it can be:
python3 -m http.server
...
Reflection: How to Invoke Method with parameters
...
Change "methodInfo" to "classInstance", just like in the call with the null parameter array.
result = methodInfo.Invoke(classInstance, parametersArray);
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How does strtok() split the string into tokens in C?
... string into tokens. I am unable to understand from the manual what it actually does.
15 Answers
...
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is no
...ode and select Activity Monitor. Take a look at the running processes.
Normally most will be idle or running. When the problem occurs you can identify any blocked process by the process state. If you right-click on the process and select details it'll show you the last query executed by the process....
Counting null and non-null values in a single query
...
If I understood correctly you want to count all NULL and all NOT NULL in a column...
If that is correct:
SELECT count(*) FROM us WHERE a IS NULL
UNION ALL
SELECT count(*) FROM us WHERE a IS NOT NULL
Edited to have the full query, after reading the comments :]
S...
Remove duplicated rows
...
Do note that this will remove all the columns except for the three first ones.
– GuillaumeL
Apr 1 '19 at 13:47
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