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What is the best way to ensure only one instance of a Bash script is running? [duplicate]
...e
### HEADER ###
LOCKFILE="/var/lock/`basename $0`"
LOCKFD=99
# PRIVATE
_lock() { flock -$1 $LOCKFD; }
_no_more_locking() { _lock u; _lock xn && rm -f $LOCKFILE; }
_prepare_locking() { eval "exec $LOCKFD>\"$LOCKFILE\""; trap _no_more_locking EXIT; }
# ON START
_prepare_l...
Python Pandas: Get index of rows which column matches certain value
...tion and then create slices for use in iloc(). The only thing I see is get_loc, but it cannot take an array.
– sheridp
Apr 21 '16 at 0:47
3
...
How do I use prepared statements in SQlite in Android?
... Below are some examples:
Create a table
String sql = "CREATE TABLE table_name (column_1 INTEGER PRIMARY KEY, column_2 TEXT)";
SQLiteStatement stmt = db.compileStatement(sql);
stmt.execute();
The execute() method does not return a value so it is appropriate to use with CREATE and DROP but not in...
Python Dictionary Comprehension
...a subclass of dict which works somewhat like a defaultdict if you override __missing__:
>>> class KeyDict(dict):
... def __missing__(self, key):
... #self[key] = key # Maybe add this also?
... return key
...
>>> d = KeyDict()
>>> d[1]
1
>>> d[2]
...
Objective-C declared @property attributes (nonatomic, copy, strong, weak)
...maticReferenceCounting.html#ownership.spelling.property
assign implies __unsafe_unretained ownership.
copy implies __strong ownership, as well as the usual behavior of copy
semantics on the setter.
retain implies __strong ownership.
strong implies __strong ownership.
unsafe...
What is the difference between Python's list methods append and extend?
...ppend
The list.append method appends an object to the end of the list.
my_list.append(object)
Whatever the object is, whether a number, a string, another list, or something else, it gets added onto the end of my_list as a single entry on the list.
>>> my_list
['foo', 'bar']
>>&...
Python: Why is functools.partial necessary?
...mbda:
>>> pickle.dumps(partial(int))
'cfunctools\npartial\np0\n(c__builtin__\nint\np1\ntp2\nRp3\n(g1\n(tNNtp4\nb.'
>>> pickle.dumps(lambda x: int(x))
Traceback (most recent call last):
File "<ipython-input-11-e32d5a050739>", line 1, in <module>
pickle.dumps(lambd...
Android - Camera preview is sideways
...Parameters();
Display display = ((WindowManager)getSystemService(WINDOW_SERVICE)).getDefaultDisplay();
if(display.getRotation() == Surface.ROTATION_0) {
parameters.setPreviewSize(height, width);
mCamera.setDisplayOrientation(90);
}
if(disp...
How to crop an image in OpenCV using Python
...y simple. Use numpy slicing.
import cv2
img = cv2.imread("lenna.png")
crop_img = img[y:y+h, x:x+w]
cv2.imshow("cropped", crop_img)
cv2.waitKey(0)
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Python argparse: How to insert newline in the help text?
... RawTextHelpFormatter
parser = ArgumentParser(description='test', formatter_class=RawTextHelpFormatter)
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