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Sample random rows in dataframe
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The data.table package provides the function DT[sample(.N, M)], sampling M random rows from the data table DT.
library(data.table)
set.seed(10)
mtcars <- data.table(mtcars)
mtcars[sample(.N, 6)]
mpg cyl disp hp drat wt ...
What’s the difference between ScalaTest and Scala Specs unit test frameworks?
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Mockito has been given a nice BDD support in specs: Mockito
specs has DataTables which allow to group a lot of small example in a sort of table (if you can stand operators being used as the table delimiters)
In specs, you can define examples which are nested as libidum and automatically cleaned-up ...
SQL Server IN vs. EXISTS Performance
... test case does not mean that the optimizer will do the exact same plan on tables with different statistics. This might lead someone to think the answer is partial - but the nonexistence of multiple semijoin operators is fact. Maybe I'll find a list somewhere and link it.
– Geo...
jquery get all form elements: input, textarea & select
...on, sometimes this differs from children such as when the form tag is in a table and is not closed.
var summary = [];
$('form').each(function () {
summary.push('Form ' + this.id + ' has ' + $(this).find(':input').length + ' child(ren).');
summary.push('Form ' + this.id + ' has ' + th...
How do you format the day of the month to say “11th”, “21st” or “23rd” (ordinal indicator)?
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case 3: return "rd";
default: return "th";
}
}
The table from @kaliatech is nice, but since the same information is repeated, it opens the chance for a bug. Such a bug actually exists in the table for 7tn, 17tn, and 27tn (this bug might get fixed as time goes on because of th...
How to override !important?
...ate. However, on my calendar page, the original CSS has the height of each table cell set with the !important declaration:
...
Create a custom View by inflating a layout?
...u are using a bit of xml repeatedly. Suppose, for example, that you have a table that you wish to create a table row for each entry in a list. You've set up some xml:
In my_table_row.xml:
<?xml version="1.0" encoding="utf-8"?>
<TableRow xmlns:android="http://schemas.android.com/apk/res/an...
How to do associative array/hashing in JavaScript
...ash/AS3 Dictionary does. In JavaScript, var obj1 = {}; var obj2 = {}; var table= {}; table[obj1] = "A"; table[obj2] = "B"; alert(table[obj1]); //displays B, because it can't differentiate between keys obj1 and obj2; they're both converted to string and just become something like "Object". Total fa...
Code-first vs Model/Database-first [closed]
... unique index on a field or you can not delete hierarchical data in a tree table for this you need a CTE using the context.Table.SqlQuery("select..."). Model/Database first do not have these drawbacks.
– Elisabeth
Jan 31 '13 at 13:51
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What does “static” mean in C?
...If we compile:
int i = 0;
static int si = 0;
and disassemble the symbol table with:
readelf -s main.o
the output contains:
Num: Value Size Type Bind Vis Ndx Name
5: 0000000000000004 4 OBJECT LOCAL DEFAULT 4 si
10: 0000000000000000 4 OBJECT GLOBAL DEFAULT...