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Is there a difference between “==” and “is”?
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is will return True if two variables point to the same object, == if the objects referred to by the variables are equal.
>>> a = [1, 2, 3]
>>> b = a
>>> b is a
True
>>> b == a
True
# Make a new copy of list...
Java - get pixel array from image
...((DataBufferByte) bufferedImage.getRaster().getDataBuffer()).getData();
If you are working with large images and performance is an issue, the first method is absolutely not the way to go. The getRGB() method combines the alpha, red, green and blue values into one int and then returns the result, ...
How to get the directory of the currently running file?
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func main() {
dir, err := filepath.Abs(filepath.Dir(os.Args[0]))
if err != nil {
log.Fatal(err)
}
fmt.Println(dir)
}
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How can I print variable and string on same line in Python?
I am using python to work out how many children would be born in 5 years if a child was born every 7 seconds. The problem is on my last line. How do I get a variable to work when I'm printing text either side of it?
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Javascript shorthand ternary operator
...ber || 1;
Something like that what you're looking for, where it defaults if undefined?
var foo = bar || 1; // 1
var bar = 2;
foo = bar || 1; // 2
By the way, this works for a lot of scenarios, including objects:
var foo = bar || {}; // secure an object is assigned when bar is absent
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Check if null Boolean is true results in exception
...s any other object.
In your particular case, your Boolean is null and the if statement triggers an implicit conversion to boolean that produces the NullPointerException. You may need instead:
if(bool != null && bool) { ... }
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How to quickly and conveniently disable all console.log statements in my code?
...tion enableLogger()
{
if(oldConsoleLog == null)
return;
window['console']['log'] = oldConsoleLog;
};
pub.disableLogger = function disableLogger()
...
Cleaning `Inf` values from an R dataframe
...ame]])), j = .name,value =NA)))
Or using column numbers (possibly faster if there are a lot of columns):
for (j in 1:ncol(DT)) set(DT, which(is.infinite(DT[[j]])), j, NA)
Timings
# some `big(ish)` data
dat <- data.frame(a = rep(c(1,Inf), 1e6), b = rep(c(Inf,2), 1e6),
c = ...
What's the canonical way to check for type in Python?
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To check if o is an instance of str or any subclass of str, use isinstance (this would be the "canonical" way):
if isinstance(o, str):
To check if the type of o is exactly str (exclude subclasses):
if type(o) is str:
The followi...
The performance impact of using instanceof in Java
...now that OO design generally tries to avoid using instanceof , that is a different story and this question is purely related to performance. I was wondering if there is any performance impact? Is is just as fast as == ?
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