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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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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...
How to remove/delete a large file from commit history in Git repository?
...han 100M my-repo.git
Any files over 100MB in size (that aren't in your latest commit) will be removed from your Git repository's history. You can then use git gc to clean away the dead data:
$ git gc --prune=now --aggressive
The BFG is typically at least 10-50x faster than running git-filter-br...
How to parse an RSS feed using JavaScript?
...'#rss-viewer')[0].innerHTML = aDocumentFragmentOfAllEntries.innerHTML;
Test Data
Using this question's feed, which as of this writing gives:
<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:creativeCommons="http://backend.userland.com/creativeComm...
Convert JavaScript string in dot notation into an object reference
...
@Mr.B. the latest version of Lodash has a third, optional, argument for defaultValue. The _.get() method returns the default value if _.get() resolves to undefined, so set it to whatever you want and watch for the value you set.
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