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Aggregate / summarize multiple variables per group (e.g. sum, mean)
... The recast function (also from reshape2) integrates the melt and dcast function in one go for tasks like this: recast(df1, year + month ~ variable, sum, id.var = c("date", "year", "month"))
– Jaap
May 13 '16 at 6:17
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How do I run a batch script from within a batch script?
...ile.bat
This will block (pause) the execution of the current batch file, and it will wait until the CALLed one completes.
If you don't want it to block, use START instead.
Get the nitty-gritty details by using CALL /? or START /? from the cmd prompt.
...
Change a column type from Date to DateTime during ROR migration
...f you're wondering why a single change method isn't used instead of the up and down methods, it's because the change method doesn't support the change_column migration definition.
– Dennis
Feb 25 '14 at 21:35
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Sending multipart/formdata with jQuery.ajax
...P native array instead of a counter
Just name your file elements the same and end the name in brackets:
jQuery.each(jQuery('#file')[0].files, function(i, file) {
data.append('file[]', file);
});
$_FILES['file'] will then be an array containing the file upload fields for every file uploaded. ...
psql: FATAL: role “postgres” does not exist
...ep is to check the missing role: What is the output within psql of the command \du ? On my Ubuntu system the relevant line looks like this:
List of roles
Role name | Attributes | Member of
-----------+-----------------------------------+-------...
How to access the GET parameters after “?” in Express?
...e value I'm looking for.
req.params refers to items with a ':' in the URL and req.query refers to items associated with the '?'
Example:
GET /something?color1=red&color2=blue
Then in express, the handler:
app.get('/something', (req, res) => {
req.query.color1 === 'red' // true
...
What does the `#` operator mean in Scala?
... such a subclass. In other words, there's no A.B class, but there are a1.B and a2.B classes, and they are different classes, as the error message is telling us above.
If you did not understand that, look up path dependent types.
Now, # makes it possible for you to refer to such nested classes with...
How can I concatenate two arrays in Java?
...
Here's a simple method that will concatenate two arrays and return the result:
public <T> T[] concatenate(T[] a, T[] b) {
int aLen = a.length;
int bLen = b.length;
@SuppressWarnings("unchecked")
T[] c = (T[]) Array.newInstance(a.getClass().getComponentType(...
pinterest api documentation [closed]
...ate a log in action to the /v3/login endpoint with your Pinterest username and password. It will return an access_token if request is successful. I'm not going into details about how this is done, as this is never meant to be part of the public API and is meant only for users logging into Pinterest ...
What is the printf format specifier for bool?
...t something like "%d" which would cause problems. The fputs, on the other hand, is a better option.
– paxdiablo
Oct 15 '14 at 2:40
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