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Trimming a huge (3.5 GB) csv file to read into R
...that has a lot of detail and incomplete rows (leading Access and SQL to choke). It's county level data set broken into segments, sub-segments, and sub-sub-segments (for a total of ~200 factors) for 40 years. In short, it's huge, and it's not going to fit into memory if I try to simply read it.
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How to grep (search) committed code in the Git history
...ent (i.e., actual lines of source, as opposed to commit messages and the like), you need to do:
git grep <regexp> $(git rev-list --all)
git rev-list --all | xargs git grep <expression> will work if you run into an "Argument list too long" error.
If you want to limit the search to som...
How do you sort a dictionary by value?
I often have to sort a dictionary, consisting of keys & values, by value. For example, I have a hash of words and respective frequencies, that I want to order by frequency.
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How to check if a String contains only ASCII?
...c) returns true if the character is a letter. But is there a way to quickly find if a String only contains the base characters of ASCII?
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Is there a version control system for database structure changes?
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In Ruby on Rails, there's a concept of a migration -- a quick script to change the database.
You generate a migration file, which has rules to increase the db version (such as adding a column) and rules to downgrade the version (such as removing a column). Each migration is numbered,...
How do I escape a single quote in SQL Server?
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Recursively list files in Java
...o I recursively list all files under a directory in Java? Does the framework provide any utility?
26 Answers
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Cache an HTTP 'Get' service response in AngularJS?
I want to be able to create a custom AngularJS service that makes an HTTP 'Get' request when its data object is empty and populates the data object on success.
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Why are local variables not initialized in Java?
...programmer's decision to set the value of the variable and it should not take a default value. If the programmer, by mistake, did not initialize a local variable and it take default value, then the output could be some unexpected value. So in case of local variables, the compiler will ask the progra...
How to remove all white space from the beginning or end of a string?
...entations at least, if there are no white-spaces to be trimmed, you get back the same string object you started with:
csharp> string a = "a";
csharp> string trimmed = a.Trim();
csharp> (object) a == (object) trimmed;
returns true
I don't know whether this is guaranteed by the language.)
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