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Evaluate expression given as a string
...ied. For example, if you have a pre-defined variable name equal to "David" and you reassign using eval(parse(text = "name") == "Alexander", you will get an error because eval & parse do not return an R expression that can be evaluated.
– Crt
Aug 1 '16 at 22...
Specifying and saving a figure with exact size in pixels
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Matplotlib doesn't work with pixels directly, but rather physical sizes and DPI. If you want to display a figure with a certain pixel size, you need to know the DPI of your monitor. For example this link will detect that for you.
If you have an image of 3841x7195 pixels it is unlikely that you m...
How to read a large file - line by line?
... for line in f:
# Do something with 'line'
The with statement handles opening and closing the file, including if an exception is raised in the inner block. The for line in f treats the file object f as an iterable, which automatically uses buffered I/O and memory management so you don't ...
Programmatically creating Markdown tables in R with KnitR
I am just starting to learn about KnitR and the use of Markdown in generating R documents and reports. This looks to be perfect for a lot of the day to day reporting that I have to do with my job. However, one thing that I'm not seeing is an easy way to print data frames and tables using Markdown fo...
SQL Server add auto increment primary key to existing table
...lues when you do this:
ALTER TABLE dbo.YourTable
ADD ID INT IDENTITY
and then you can make it the primary key:
ALTER TABLE dbo.YourTable
ADD CONSTRAINT PK_YourTable
PRIMARY KEY(ID)
or if you prefer to do all in one step:
ALTER TABLE dbo.YourTable
ADD ID INT IDENTITY
CONSTRA...
How do I get a Cron like scheduler in Python? [closed]
I'm looking for a library in Python which will provide at and cron like functionality.
9 Answers
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svn: replace trunk with branch
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Use svn move to move the contents of the old trunk somewhere else and rename the branch to trunk afterward.
Note that copy and move in svn work like file operations. You can use them to move/copy stuff around in your repository and these changes are versioned as well. Think of "move" as "c...
What does “|=” mean? (pipe equal operator)
I tried searching using Google Search and Stack Overflow, but it didn't show up any results. I have seen this in opensource library code:
...
Get top 1 row of each group
...nt to:
maintain status in 2 places
preserve status history
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As it stands, you preserve status history. If you want latest status in the parent table too (which is denormalisation) you'd need a trigger to maintain "status" in the parent. or drop this status history table.
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What is the ultimate postal code and zip regex?
I'm looking for the ultimate postal code and zip code regex. I'm looking for something that will cover most (hopefully all) of the world.
...