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Simple calculations for working with lat/lon and km distance?
...ie on the same line of longitude (north/south), they lie on a great circle and the conversion factor is just the Earth's polar circumference divided by 360 degrees. But it's different for east-west measurements, because (except for the equator) you're not measuring along a "great circle", so the "c...
Do we still need end slashes in HTML5?
... they do not need an end tag.
Void elements
area, base, br, col, command, embed, hr, img, input, keygen, link, meta, param, source, track, wbr
...
Void elements only have a start tag; end tags must not be specified for void elements.
W3C | WHATWG
That being said it's not strict parsi...
How do I skip a match when using Ctrl+D for multiple selections in Sublime Text 2?
...bo until what you want to skip is highlighted. E.g. if you have 3 matches, and you want to skip the 2nd, first highlight the 1st, press CTRL+D to highlight the 2nd, THEN press the key combo to skip the 2nd match and highlight the 3rd. Help?
– Tyler Collier
Oct ...
Replace a value in a data frame based on a conditional (`if`) statement
...
Easier to convert nm to characters and then make the change:
junk$nm <- as.character(junk$nm)
junk$nm[junk$nm == "B"] <- "b"
EDIT: And if indeed you need to maintain nm as factors, add this in the end:
junk$nm <- as.factor(junk$nm)
...
Submit form using a button outside the tag
...ubmit> or <input type="submit"> element whithin the <form>, and an associated <label> element outside of it. It would look like this:
<form method="get" action="something.php">
<input type="text" name="name" />
<input type="submit" id="submit-form" clas...
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.
...
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
...
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
...
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. ...
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
...