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How to get line count of a large file cheaply in Python?
I need to get a line count of a large file (hundreds of thousands of lines) in python. What is the most efficient way both memory- and time-wise?
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How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
How can I use regular expressions in Excel and take advantage of Excel's powerful grid-like setup for data manipulation?
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Dynamically select data frame columns using $ and a character value
I have a vector of different column names and I want to be able to loop over each of them to extract that column from a data.frame. For example, consider the data set mtcars and some variable names stored in a character vector cols . When I try to select a variable from mtcars using a dynamic s...
Connect to a locally built Jekyll Server using mobile devices in the LAN
After using jekyll serve on one machine, a WEBrick server is set up and the site can be accessed from localhost:4000 on this particular PC.
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What's the (hidden) cost of Scala's lazy val?
One handy feature of Scala is lazy val , where the evaluation of a val is delayed until it's necessary (at first access).
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What is the colon operator in Ruby?
When I say { :bla => 1, :bloop => 2 } , what exactly does the : do? I read somewhere about how it's similar to a string, but somehow a symbol.
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SQL keys, MUL vs PRI vs UNI
What is the difference between MUL , PRI and UNI in MySQL?
4 Answers
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Removing leading zeroes from a field in a SQL statement
I am working on a SQL query that reads from a SQLServer database to produce an extract file. One of the requirements to remove the leading zeroes from a particular field, which is a simple VARCHAR(10) field. So, for example, if the field contains '00001A', the SELECT statement needs to return the...
What's the simplest way to test whether a number is a power of 2 in C++?
I need a function like this:
17 Answers
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