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Group a list of objects by an attribute : Java
...ew HashMap<Integer, List<Student>>();
Iterate over this code and add students to the HashMap:
if (!hashMap.containsKey(locationId)) {
List<Student> list = new ArrayList<Student>();
list.add(student);
hashMap.put(locationId, list);
} else {
hashMap.get(loca...
How do I check if a type provides a parameterless constructor?
...ou can check if you have a value type using the Type.IsValueType property, and create instances using Activator.CreateInstance(Type);
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Rename specific column(s) in pandas
...' else x for x in df.columns]
Or, construct a mapping using a dictionary and perform the list-comprehension with it's get operation by setting default value as the old name:
col_dict = {'gdp': 'log(gdp)', 'cap': 'cap_mod'} ## key→old name, value→new name
df.columns = [col_dict.get(x, x) fo...
How to scale SVG image to fill browser window?
...my site using (roughly) this technique, albeit with 5% padding all around, and using position:absolute instead of position:fixed:
http://phrogz.net/svg/svg_in_xhtml5.xhtml
(Using position:fixed prevents a very edge-case scenario of linking to a sub-page anchor on the page, and overflow:hidden can e...
Compare integer in bash, unary operator expected
...at variable substitutions are done, the shell proceeds with the comparison and.... fails because it cannot see anything intelligible to the left of -gt. However, quoting $i:
if [ "$i" -ge 2 ] ; then ...
becomes:
if [ " " -ge 2 ] ; then ...
The shell now sees the double-quotes, and knows th...
C compile error: “Variable-sized object may not be initialized”
...printf( "%d", boardAux[1][2] ) compiles fine. The compiler knows the sizes and knows in what position in memory the (1,2)-th element is. If you use dynamic allocation the array is uni-dimensional and you must perform the math yourself: printf("%d", boardAux[ 1*length + 2 ])
– D...
Simple way to convert datarow array to datatable
...
Why not iterate through your DataRow array and add (using DataRow.ImportRow, if necessary, to get a copy of the DataRow), something like:
foreach (DataRow row in rowArray) {
dataTable.ImportRow(row);
}
Make sure your dataTable has the same schema as the DataRows...
Setting Windows PowerShell environment variables
...nd out that setting the PATH environment variable affects only the old command prompt. PowerShell seems to have different environment settings. How do I change the environment variables for PowerShell (v1)?
...
WPF Bind to itself
I've got a WPF Window , and somewhere there is a ListView where I bind a List<string> to.
1 Answer
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Reference list item by index within Django template?
This may be simple, but I looked around and couldn't find an answer. What's the best way to reference a single item in a list from a Django template?
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