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How to check if hex color is “too black”?
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You have to extract the three RGB components individually, and then use a standard formula to convert the resulting RGB values into their perceived brightness.
Assuming a six character colour:
var c = c.substring(1); // strip #
var rgb = parseInt(c, 16); // convert rrg...
Finding duplicate values in a SQL table
...ly group on both of the columns.
Note: the older ANSI standard is to have all non-aggregated columns in the GROUP BY but this has changed with the idea of "functional dependency":
In relational database theory, a functional dependency is a constraint between two sets of attributes in a relation...
Changing Vim indentation behavior by file type
...h a width of 2 characters for indenting (the noexpandtab option is set globally elsewhere in my configuration).
This is described here: http://vimdoc.sourceforge.net/htmldoc/usr_05.html#05.4, scroll down to the section on filetype plugins.
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MVC Razor dynamic model, 'object' does not contain definition for 'PropertyName'
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According to David Ebbo, you can't pass an anonymous type into a dynamically-typed view because the anonymous types are compiled as internal. Since the CSHTML view is compiled into a separate assembly, it can't access the anonymous type's properties.
EDIT #2:
David Ebbo has edited his post with...
Mean per group in a data.frame [duplicate]
... the many ways to specify the variables to act on. Here, vars(-Month) says all variables except Month.
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How to randomize (or permute) a dataframe rowwise and columnwise?
...] 1 0 0 1 0
[4,] 0 0 1 0 1
To explain the call:
out <- permatswap(mat, times = 99, burnin = 20000, thin = 500, mtype = "prab")
times is the number of randomised matrices you want, here 99
burnin is the number of swaps made before we start taking random samples....
LINQ query on a DataTable
...s.Cast<DataRow>().Where(myRow => (int)myRow["RowNo"] == 1). Personally, I don't find the call to AsEnumerable() any more complicated than the call to Cast<DataRow>(). As far as I know, the performance is the same, so it's just a matter of preference.
– Collin K
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Unable to install gem - Failed to build gem native extension - cannot load such file — mkmf (LoadErr
...ing so i had to run open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg
That didnt work for me at first because the version of CommandLineTools i had installed did not have the "Packages" folder. So i uninstalled and reinstalled like this:
rm -rf /Library/Devel...
Django: Set foreign key using integer?
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Yep:
employee = Employee(first_name="Name", last_name="Name")
employee.type_id = 4
employee.save()
ForeignKey fields store their value in an attribute with _id at the end, which you can access directly to avoid visiting the database.
The _id version of...
PHP Fatal error: Call to undefined function json_decode()
Apache is logging PHP Fatal error: Call to undefined function json_decode() . After some googling, it seems this problem is a result of not having the latest version of php. Oddly, running php --version ouputs
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