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Understanding exactly when a data.table is a reference to (vs a copy of) another data.table
...le(a = c(1, 2), b = c(11, 12))
newDT <- DT
.Internal(inspect(DT))
# @0000000003B7E2A0 19 VECSXP g0c7 [OBJ,NAM(2),ATT] (len=2, tl=100)
# @00000000040C2288 14 REALSXP g0c2 [NAM(2)] (len=2, tl=0) 1,2
# @00000000040C2250 14 REALSXP g0c2 [NAM(2)] (len=2, tl=0) 11,12
# ATTRIB: # ..snip..
.Inte...
Virtualbox “port forward” from Guest to Host [closed]
... and find out the ip address:
ifconfig
example of result (ip address is 10.0.2.15):
eth0 Link encap:Ethernet HWaddr 08:00:27:AE:36:99
inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0
Go to Vbox instance window -> Menu -> Network adapters:
adapter should be NAT
clic...
How do I make a transparent canvas in html5?
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edited Apr 16 '14 at 1:20
Lee Taylor
5,93777 gold badges2626 silver badges4343 bronze badges
answered ...
How to reliably open a file in the same directory as a Python script
...
203
I always use:
__location__ = os.path.realpath(
os.path.join(os.getcwd(), os.path.dirname(__...
Logic to test that 3 of 4 are True
... (§4.7/4) indicates that converting bool to int gives the expected values 0 or 1.
In Java and C#, you can use the following construct:
if ((a?1:0) + (b?1:0) + (c?1:0) + (d?1:0) == 3)
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share
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Change date of git tag (or GitHub Release based on it)
...re-create new releases from the new tags
In code:
# Fixing tag named '1.0.1'
git checkout 1.0.1 # Go to the associated commit
git tag -d 1.0.1 # Locally delete the tag
git push origin :refs/tags/1.0.1 # Push this deletion up to GitHub
# Create the tag, with a date d...
How do I draw a shadow under a UIView?
...eeds to happen after
CGContextSetShadow(currentContext, CGSizeMake(-15, 20), 5);
but before
CGContextRestoreGState(currentContext);
So if you want the superclass's drawRect: to be 'wrapped' in a shadow, then how about if you rearrange your code like this?
- (void)drawRect:(CGRect)rect {
...
Swift - How to convert String to Double
...e: The NSString doubleValue property is not recommended because it returns 0 if the value cannot be converted (i.e.: bad user input).
let lessPrecisePI = Float("3.14")
let morePrecisePI = Double("3.1415926536")
let invalidNumber = Float("alphabet") // nil, not a valid number
Unwrap the values to...
Splitting a list into N parts of approximately equal length
...ken due to rounding errors. Do not use it!!!
assert len(chunkIt([1,2,3], 10)) == 10 # fails
Here's one that could work:
def chunkIt(seq, num):
avg = len(seq) / float(num)
out = []
last = 0.0
while last < len(seq):
out.append(seq[int(last):int(last + avg)])
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How do you log all events fired by an element in jQuery?
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edited Jul 30 '13 at 11:32
Ian Clark
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