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Applying a function to every row of a table using dplyr?
...%
group_by(1:nrow(iris)) %>%
do(do_fn) %>%
rbind_all()
Testing the performance,
library(plyr) # plyr_1.8.4.9000
library(dplyr) # dplyr_0.8.0.9000
library(purrr) # purrr_0.2.99.9000
library(microbenchmark)
d1_count <- 1000
d2_count <- 10
d1 <- data.frame(a=runif...
Differences between Perl and PHP [closed]
...$foo ||= 'default' to set $foo to a value if it's not already set. The shortest way of doing this in PHP is $foo = isset($foo) ? $foo : 'default'; (Update, in PHP 7.0+ you can do $foo = $foo ?? 'default')
Perl variable names indicate built-in type, of which Perl has three, and the type specifier is ...
CSS selector for first element with class
... @Willem Just change first-child to last-child, but I see after testing that this doesn't always does the trick.
– A1rPun
Sep 29 '14 at 8:19
3
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If Python is interpreted, what are .pyc files?
...
One test of 'compiled': is it compiled to actual machine instructions? Python bytecode are not machine instructions, and neither are Java 'JVM' instructions, so neither of these languages are compiled by that definition. But both...
Is R's apply family more than syntactic sugar?
...ferent numbers to you - the for loop improves considerably: for your three tests, I get 2.798 0.003 2.803; 4.908 0.020 4.934; 1.498 0.025 1.528, and vapply is even better: 1.19 0.00 1.19
– naught101
Jun 26 '12 at 7:11
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Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?
...ranslating their example to use your construct:
val x = new Slot[String]("test") // Make a slot
val y: Slot[Any] = x // Ok, 'cause String is a subtype of Any
y.set(new Rational(1, 2)) // Works, but now x.get() will blow up
If you feel I'm not understanding your question (a dis...
What are the best PHP input sanitizing functions?
...scape_string. Also the enclosing quotes, but everybody does it, and if you test what you do, you end up with a SQL syntax error with this omission. The real dangerous part is handled with mysql_real_escape_string.
– Savageman
Jun 27 '10 at 14:27
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What is the most efficient/elegant way to parse a flat table into a tree?
...BLE AS m JOIN MyTree AS t ON m.ParentId = t.Id
)
SELECT * FROM MyTree;
I tested recursive queries in MySQL 8.0 in my presentation Recursive Query Throwdown in 2017.
Below is my original answer from 2008:
There are several ways to store tree-structured data in a relational database. What you s...
Difference between git checkout --track origin/branch and git checkout -b branch origin/branch
...
@Green The test you do is with origin/new-branch instead of origin/branch. Are you aware of that?
– Robert Siemer
Apr 13 '19 at 22:02
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Rebasing and what does one mean by rebasing pushed commits
...ID (in this case, a, b, c, and d). You'll notice that d is currently the latest commit (or HEAD) of the master branch.
Here, we have two branches: master and my-branch. You can see that master and my-branch both contain commits a and b, but then they start to diverge: master contains c and d, whil...