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File I/O in Every Programming Language [closed]
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Python 3
with open('fileio.txt', 'w') as f:
f.write('hello')
with open('fileio.txt', 'a') as f:
f.write('\nworld')
with open('fileio.txt') as f:
s = f.readlines()[1]
print(s)
Clarifications
readlines() returns a...
Pairs from single list
...nd the need to process a list by pairs. I was wondering which would be the pythonic and efficient way to do it, and found this on Google:
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ImportError: Cannot import name X
.... This is extremely important in C++, and even if it's not the #1 thing in Python, it's still a really good idea to follow this rule. Never have two classes which know each other, ever. If you need help with creating the structure for your classes, post rest of the code too. How exactly (in terms of...
Create numpy matrix filled with NaNs
...atives a[:] = numpy.nan here and a.fill(numpy.nan) as posted by Blaenk:
$ python -mtimeit "import numpy as np; a = np.empty((100,100));" "a.fill(np.nan)"
10000 loops, best of 3: 54.3 usec per loop
$ python -mtimeit "import numpy as np; a = np.empty((100,100));" "a[:] = np.nan"
10000 loops, best of...
How to free memory in Java?
...s by relying on the garbage collector.
This memory management whitepaper (PDF) may help explain what's going on.
You can also call System.gc() to suggest that the garbage collector run immediately. However, the Java Runtime makes the final decision, not your code.
According to the Java documenta...
“find: paths must precede expression:” How do I specify a recursive search that also finds files in
...scribed in @Chris J's answer, here is what worked for me
find . -name one.pdf -o -name two.txt -o -name anotherone.jpg
-o or -or is logical OR. See Finding Files on Gnu.org for more information.
I was running this on CygWin.
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Python string.join(list) on object array rather than string array
In Python, I can do:
4 Answers
4
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round() for float in C++
...according to http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf)
#include <cmath>
#include <iostream>
int main(int argc, char** argv) {
std::cout << "round(0.5):\t" << round(0.5) << std::endl;
std::cout << "round(-0.5):\t" << round(-0.5)...
OSError: [Errno 2] No such file or directory while using python subprocess in Django
I am trying to run a program to make some system calls inside Python code using subprocess.call() which throws the following error:
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Python - json without whitespaces
...hile indent=None (default) does not in 2.7. All is clearly stated at: docs.python.org/3/library/json.html#json.dump
– Ciro Santilli 郝海东冠状病六四事件法轮功
Jul 28 '16 at 14:01
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