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What are the Ruby Gotchas a newbie should be warned about? [closed]
... while (not(expression)); in C/C++/...), actually never runs the statement if the expression is already true. This is because statement until expression is actually syntactic sugar over
until expression
statement
end
, the equivalent of which in C/C++ is while (not(expression)) statement; just ...
Constantly print Subprocess output while process is running
...d stdout_line
popen.stdout.close()
return_code = popen.wait()
if return_code:
raise subprocess.CalledProcessError(return_code, cmd)
# Example
for path in execute(["locate", "a"]):
print(path, end="")
...
Iterate through a C++ Vector using a 'for' loop
... flexible.
All standard library containers support and provide iterators. If at a later point of development you need to switch to another container, then this code does not need to be changed.
Note: Writing code which works with every possible standard library container is not as easy as it might...
Replace all elements of Python NumPy Array that are greater than some value
...and most concise way to do this is to use NumPy's built-in Fancy indexing. If you have an ndarray named arr, you can replace all elements >255 with a value x as follows:
arr[arr > 255] = x
I ran this on my machine with a 500 x 500 random matrix, replacing all values >0.5 with 5, and it t...
How to check if a value exists in a dictionary (python)
... in case you wonder why... the reason is that each of the above returns a different type of object, which may or may not be well suited for lookup operations:
>>> type(d.viewvalues())
<type 'dict_values'>
>>> type(d.values())
<type 'list'>
>>> type(d.itervalue...
Convert data.frame columns from factors to characters
...
Just following on Matt and Dirk. If you want to recreate your existing data frame without changing the global option, you can recreate it with an apply statement:
bob <- data.frame(lapply(bob, as.character), stringsAsFactors=FALSE)
This will convert al...
Find an element in a list of tuples
...
If you just want the first number to match you can do it like this:
[item for item in a if item[0] == 1]
If you are just searching for tuples with 1 in them:
[item for item in a if 1 in item]
...
Comparing two dictionaries and checking how many (key, value) pairs are equal
I have two dictionaries, but for simplification, I will take these two:
26 Answers
26
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Strangest language feature
...ts & semicolons syntax, it's not apparent at all that newlines are significant.
– Tamas Czinege
Jan 10 '10 at 15:27
...
Detect if a NumPy array contains at least one non-numeric value?
I need to write a function which will detect if the input contains at least one value which is non-numeric. If a non-numeric value is found I will raise an error (because the calculation should only return a numeric value). The number of dimensions of the input array is not known in advance - the fu...