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UITableView with fixed section headers
Greets,
I'm reading that the default behaviour of UITableView is to pin section header rows to the top of the table as you scroll through the sections until the next section pushes the previos section row out of view.
...
Reshaping data.frame from wide to long format
I have some trouble to convert my data.frame from a wide table to a long table.
At the moment it looks like this:
9 Answe...
How many GCC optimization levels are there?
...is a strong indicator that there are only 3 levels.
opts.c:default_options_table
opt_levels is so interesting, that we grep OPT_LEVELS_3_PLUS, and come across opts.c:default_options_table:
static const struct default_options default_options_table[] = {
/* -O1 optimizations. */
{ OPT_LEVELS_...
What is the proper way to re-attach detached objects in Hibernate?
...nate Session (a.k.a Persistence Context) and is not mapped to any database table row is considered to be in the New (Transient) state.
To become persisted we need to either explicitly call the EntityManager#persist method or make use of the transitive persistence mechanism.
Persistent (Managed)
...
Algorithm for creating a school timetable
...dering if there are known solutions for algorithm of creating a school timetable. Basically, it's about optimizing "hour-dispersion" (both in teachers and classes case) for given class-subject-teacher associations. We can assume that we have sets of classes, lesson subjects and teachers associated ...
What is the difference between HAVING and WHERE in SQL?
..., CNT=Count(1)
From Address
Where State = 'MA'
Group By City
Gives you a table of all cities in MA and the number of addresses in each city.
This code:
select City, CNT=Count(1)
From Address
Where State = 'MA'
Group By City
Having Count(1)>5
Gives you a table of cities in MA with more than ...
Mechanisms for tracking DB schema changes [closed]
...mber of files numbered 1.sql, 2.sql, 3.sql, etc. The script uses one extra table to store the current version number of the database. The N.sql files are crafted by hand, to go from version (N-1) to version N of the database.
They can be used to add tables, add columns, migrate data from an old to ...
Why would introducing useless MOV instructions speed up a tight loop in x86_64 assembly?
...h was being incorrectly predicted due to aliasing in the branch prediction table
moving the branch eliminated the alias and allowed the branch to be predicted correctly
Your Core2 doesn't keep a separate history record for each conditional jump. Instead it keeps a shared history of all conditional...
Retrieving the last record in each group - MySQL
There is a table messages that contains data as shown below:
27 Answers
27
...
Extract a substring according to a pattern
...sapply(strsplit(string, ":"), "[", 2)
## [1] "E001" "E002" "E003"
3) read.table
read.table(text = string, sep = ":", as.is = TRUE)$V2
## [1] "E001" "E002" "E003"
4) substring
This assumes second portion always starts at 4th character (which is the case in the example in the question):
substring(st...