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Drop data frame columns by name
...multiple variables:
within(df, rm(x, y))
Or if you're dealing with data.tables (per How do you delete a column by name in data.table?):
dt[, x := NULL] # Deletes column x by reference instantly.
dt[, !"x"] # Selects all but x into a new data.table.
or for multiple variables
dt[, c("x","y...
How to remove convexity defects in a Sudoku square?
... :=
ComponentMeasurements[Image[l], "Centroid"][[1, 2]]
gridCenters =
Table[centerOfGravity[
ImageData[Dilation[Image[h], DiskMatrix[2]]]*
ImageData[Dilation[Image[v], DiskMatrix[2]]]], {h,
horizontalGridLineMasks}, {v, verticalGridLineMasks}];
The last step is to define two i...
What is the point of function pointers?
...d what is going on inside of the abstraction. Also, implementing your own vtable in C and write object oriented code there is a really good learning experience.
– Florian
Jun 2 '12 at 10:49
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How to scroll to specific item using jQuery?
I have a big table with vertical scroll bar.
I would like to scroll to a specific line in this table using jQuery/Javascript.
...
SQL update query using joins
I have to update a field with a value which is returned by a join of 3 tables.
11 Answers
...
How do you run a SQL Server query from PowerShell?
...dapter.Fill($dataSet) | Out-Null
$connection.Close()
$dataSet.Tables
}
I have been using this so long I don't know who wrote which parts. This was distilled from others' examples, but simplified to be clear and just what is needed without extra dependencies or features.
I use and shar...
How can I get a list of all functions stored in the database of a particular schema in PostgreSQL?
...
After some searching, I was able to find the information_schema.routines table and the information_schema.parameters tables. Using those, one can construct a query for this purpose. LEFT JOIN, instead of JOIN, is necessary to retrieve functions without parameters.
SELECT routines.routine_name, pa...
UITableView - change section header color
How can I change color of a section header in UITableView?
31 Answers
31
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How to restore to a different database in sql server?
...M, COPY_ONLY, FORMAT, INIT, STATS = 100;
-- Get the backup file list as a table variable
DECLARE @BackupFiles TABLE(LogicalName nvarchar(128),PhysicalName nvarchar(260),Type char(1),FileGroupName nvarchar(128),Size numeric(20,0),MaxSize numeric(20,0),FileId tinyint,CreateLSN numeric(25,0),DropLSN n...
Split data frame string column into multiple columns
...
5 years later adding the obligatory data.table solution
library(data.table) ## v 1.9.6+
setDT(before)[, paste0("type", 1:2) := tstrsplit(type, "_and_")]
before
# attr type type1 type2
# 1: 1 foo_and_bar foo bar
# 2: 30 foo_and_bar_2 foo ba...