replace

StringBuilder vs. String considering replace

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It is true that StringBuilder tends to be better than concatenating or modifying Strings manually, since StringBuilder is mutable, while String is immutable and you need to create a new String for each modification. Just to note, though, the Java compiler will automatically convert an example like this: String result = someString + someOtherString + … Read more

Change the values of a NumPy array that are NOT in a list of indices

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I don’t know of a clean way to do something like this: mask = np.ones(a.shape,dtype=bool) #np.ones_like(a,dtype=bool) mask[indices] = False a[~mask] = 999 a[mask] = 888 Of course, if you prefer to use the numpy data-type, you could use dtype=np.bool_ — There won’t be any difference in the output. it’s just a matter of preference really.

Replacing a HashSet Java member

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Do a remove before each add: someSet.remove(myObject); someSet.add(myObject); The remove will remove any object that is equal to myObject. Alternatively, you can check the add result: if(!someSet.add(myObject)) { someSet.remove(myObject); someSet.add(myObject); } Which would be more efficient depends on how often you have collisions. If they are rare, the second form will usually do only one … Read more

How to remove spaces from a string in Lua?

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It works, you just have to assign the actual result/return value. Use one of the following variations: str = str:gsub(“%s+”, “”) str = string.gsub(str, “%s+”, “”) I use %s+ as there’s no point in replacing an empty match (i.e. there’s no space). This just doesn’t make any sense, so I look for at least one … Read more