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Truncate number to two decimal places without rounding
...2.55
2.99999 => 2.99
4.27 => 4.27
15.7784514 => 15.77
123.5999 => 123.59
0.000000199 => 1.99 *
* As mentioned in the note, that's due to javascript implicit conversion into exponential for "1.99e-7"
And for some other values of n:
15.001097 => 15.0010 (n=4)
0.00...
Count number of rows within each group
...count the number of rows within each group. I reguarly use the aggregate function to sum data as follows:
14 Answers
...
How do I return to an older version of our code in Subversion?
...nd the right revision number.
Note down the good revision number (assuming 123 for examples below).
Update to the latest revision:
svn update
Undo all the changes between the revision you want and the latest version:
svn merge -r HEAD:123 .
svn commit "Reverted to revision 123"
(the same as Jon...
How to get the function name from within that function?
How can I access a function name from inside that function?
20 Answers
20
...
JavaScript ternary operator example with functions
...if (another_one) /etc, etc
{
...
Less good:
this > that ? testFucntion() ? thirdFunction() ? imlost() : whathappuh() : lostinsyntax() : thisisprobablybrokennow() ? //I'm lost in my own (awful) example by now.
//Not complete... or for average humans to read.
if(this != that) //Ternary wo...
What is the difference between D3 and jQuery?
...ries and components, but I didn't get past the first sentence on their web-site before feeling completely lost. I clicked on the fancy esoteric hexagonal mozaic of 'things' and it took me somewhere mysterious and unrelated. Since I fail to grasp what's going on here I assume that I'm unworthy of t...
How to deal with SettingWithCopyWarning in Pandas?
...['A'] /= 2
/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/IPython/__main__.py:1: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
df2
A
0 2.5
1 4.5
2 3.5
There...
Comparing strings by their alphabetical order
...ring.compareTo). This feature is well documented on the java documentation site.
Here is a short program that demonstrates it:
class StringCompareExample {
public static void main(String args[]){
String s1 = "Project"; String s2 = "Sunject";
verboseCompare(s1, s2);
verb...
How can I print the contents of a hash in Perl?
...
Data::Dumper is your friend.
use Data::Dumper;
my %hash = ('abc' => 123, 'def' => [4,5,6]);
print Dumper(\%hash);
will output
$VAR1 = {
'def' => [
4,
5,
6
],
'abc' => 123
...
Parse query string into an array
...alone is note accurate, it could display for example:
$url = "somepage?id=123&lang=gr&size=300";
parse_str() would return:
Array (
[somepage?id] => 123
[lang] => gr
[size] => 300
)
It would be better to combine parse_str() with parse_url() like so:
$url = "som...