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str performance in python
...100000 is evaluated by the compiler and is equivalent to a constant at run-time.
>>> import dis
>>> dis.dis(lambda: str(100000))
8 0 LOAD_GLOBAL 0 (str)
3 LOAD_CONST 1 (100000)
6 CALL_FUNCTION 1
...
Why do we copy then move?
...ion gets us nearly the same performance as the most-optimal version, but 2 times less code.
And if you are taking say 2 to 10 arguments, the reduction in code is exponential -- 2x times less with 1 argument, 4x with 2, 8x with 3, 16x with 4, 1024x with 10 arguments.
Now, we can get around this via...
Reading a file line by line in Go
... in bufio.Reader
In my testcase, ~250MB, ~2,500,000 lines, bufio.Scanner(time used: 0.395491384s) is faster than bufio.Reader.ReadString(time_used: 0.446867622s).
Source code: https://github.com/xpzouying/go-practice/tree/master/read_file_line_by_line
Read file use bufio.Scanner,
func scanFile(...
How can I check if a URL exists via PHP?
...ax), this is quick to check server side.
Waiting for a response might take time and block code execution.
Not all headers returned by get_headers() are well formed.
Use curl (if you can).
Prevent fetching the entire body/content, but only request the headers.
Consider redirecting urls:
Do you want t...
Variable declared in for-loop is local variable?
I have been using C# for quite a long time but never realised the following:
9 Answers
...
Are string.Equals() and == operator really same? [duplicate]
...an be overridden, and the implementation used will depend on the execution-time type of the target object), whereas the implementation of == used is determined based on the compile-time types of the objects:
// Avoid getting confused by interning
object x = new StringBuilder("hello").ToString();
ob...
What are the file limits in Git (number and size)?
...CVS, ie it really ends up being pretty much oriented to a "one file
at a time" model.
Which is nice in that you can have a million files, and then only check
out a few of them - you'll never even see the impact of the other
999,995 files.
Git
fundamentally never really looks at les...
How to convert a string to lower case in Bash?
...A FEW WORDS
Toggle (undocumented, but optionally configurable at compile time)
$ string="A Few Words"
$ echo "${string~~}"
a fEW wORDS
$ string="A FEW WORDS"
$ echo "${string~}"
a FEW WORDS
$ string="a few words"
$ echo "${string~}"
A few words
Capitalize (undocumented, but optionally configura...
Rename specific column(s) in pandas
... name
df.columns = [col_dict.get(x, x) for x in df.columns]
Timings:
%%timeit
df.rename(columns={'gdp':'log(gdp)'}, inplace=True)
10000 loops, best of 3: 168 µs per loop
%%timeit
df.columns = ['log(gdp)' if x=='gdp' else x for x in df.columns]
10000 loops, best of 3: 58.5 µs per loop
...
How to sort an array in Bash
...ons, but you can use arithmetic comparisons, compare wrt file modification time, etc. just use the appropriate test; you can even make it more generic and have it use a first argument that is the test function use, e.g.,
#!/bin/bash
# quicksorts positional arguments
# return is in array qsort_ret
...