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How to delete a row by reference in data.table?
...taken in order to make memory use be similar to in-place deletion is to subset a column at a time and delete. not as fast as a proper C memmove solution, but memory use is all i care about here. something like this:
DT = data.table(col1 = 1:1e6)
cols = paste0('col', 2:100)
for (col in cols){ DT[, (...
How do i find out what all symbols are exported from a shared object?
I have a shared object(dll). How do i find out what all symbols are exported from that?
9 Answers
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windbg 备忘 - 更多技术 - 清泛网 - 专注C/C++及内核技术
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sx, sxd, sxe, sxi, sxn, sxr, sx- (Set Exceptions)
The sx* commands control the action that the debugger takes when an exception occurs in the application that is being debugged, or when certain events occur.
--引http://www.vcfans.com/2010/04/wind...
Setting a system environment variable from a Windows batch file?
Is it possible to set a environment variable at the system level from a command prompt in Windows 7 (or even XP for that matter). I am running from an elevated command prompt.
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How can I check if a View exists in a Database?
...CH NEXT FROM check_cursor
INTO @viewName
WHILE @@FETCH_STATUS = 0
BEGIN
set @cmd='select * from '+@viewName
begin try
exec (@cmd)
end try
begin catch
print 'Error: The view '+@viewName+' is corrupted .'
end catch
FETCH NEXT FROM check_cursor
INTO @viewName
END
CLOSE check_cursor;
DEALLOCATE che...
How to leave a message for a github.com user
.../]*).*$/,'$1')}/events/public`).then(e=> e.json()).then(e => [...new Set([].concat.apply([],e.filter(x => x.type==='PushEvent').map(x => x.payload.commits.map(c => c.author.email)))).values()]).then(x => results.innerText = x)">GO</button>
<div id=results></div&g...
How do you find out the caller function in JavaScript?
...s in a low-level constructor during execution, to view and debug later, so setting a breakpoint isn't of use since it will be hit thousands of times)
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#1071 - Specified key was too long; max key length is 767 bytes
...t has been increased to 3072 bytes.
You also have to be aware that if you set an index on a big char or varchar field which is utf8mb4 encoded, you have to divide the max index prefix length of 767 bytes (or 3072 bytes) by 4 resulting in 191. This is because the maximum length of a utf8mb4 characte...
What is the most efficient Java Collections library? [closed]
... long mem = usedMem();
TIntIntHashMap ours = new TIntIntHashMap(SET_SIZE);
for ( int i = dataset.size(); i-- > 0; ) {
ours.put(i, i);
}
mem = usedMem() - mem;
System.err.println("trove " + mem + " bytes");
ours.clear();
}
pu...
Google Maps V3 - How to calculate the zoom level for a given bounds
... you even create the map, so you can provide its result to the initial map settings. With fitBounds, you need to create the map and then wait for the "bounds_changed" event.
– John S
Jun 25 '13 at 21:40
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