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Dynamically select data frame columns using $ and a character value
...d argument? What?! You have to realise that $, like everything else in R, (including for instance ( , + , ^ etc) is a function, that takes arguments and is evaluated. df$V1 could be rewritten as
`$`(df , V1)
or indeed
`$`(df , "V1")
But...
`$`(df , paste0("V1") )
...for instance will never ...
When should I use a table variable vs temporary table in sql server?
...s has been extended since to allow filtered index conditions. Indexes with INCLUDE-d columns or columnstore indexes are still not possible to create on table variables however.
If you will be repeatedly adding and deleting large numbers of rows from the table then use a #temporary table. That suppor...
How to print to console in pytest?
...context of what test printed that text.
However, if a test fails, it will include a section in the resulting report that shows what was printed to standard out in that particular test.
For example,
def test_good():
for i in range(1000):
print(i)
def test_bad():
print('this should...
How to access parameters in a RESTful POST method
...he query parameter version except that the names of the parameters are not included anywhere in the message.
POST /create/hello/world HTTP/1.1
Content-Length: 0
Host: www.example.com
This method shares the same encoding woes that the query parameter version. Path segments are encoded differently...
Why does Chrome incorrectly determine page is in a different language and offer to translate?
...
Try including the property xml:lang="" to the <html>, if the other solutions don't work:
<html class="no-js" lang="pt-BR" dir="ltr" xml:lang="pt-BR">
...
Get top n records for each group of grouped results
...
The edit to include the ties does not work for me. I get ERROR 1242 (21000): Subquery returns more than 1 row, presumably because of the GROUP BY. When I execute the SELECT MIN subquery alone, it generates three rows: 34, 39, 112 and the...
What's the difference between using CGFloat and float?
...ch, since most Macs now have 64-bit CPUs and Snow Leopard is fully 64-bit, including the kernel and user applications. Apple's 64-bit Transition Guide for Cocoa is a useful resource.
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Is Java Regex Thread Safe?
... quick look at the code for Matcher.java shows a bunch of member variables including the text that is being matched, arrays for groups, a few indexes for maintain location and a few booleans for other state. This all points to a stateful Matcher that would not behave well if accessed by multiple Th...
In Unix, how do you remove everything in the current directory and below it?
... is correct that rm –rf . will remove everything in the current directly including any subdirectories and their content. The single dot (.) means the current directory. be carefull not to do rm -rf .. since the double dot (..) means the previous directory.
This being said, if you are like me and ...
How to reload a page using JavaScript
...r to location.reload(). This method is compatible with all major browsers, including IE, Chrome, Firefox, Safari, Opera.
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