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What is a stack trace, and how can I use it to debug my application errors?
...ferent about this one is the "Caused by". Sometimes exceptions will have multiple "Caused by" sections. For these, you typically want to find the "root cause", which will be one of the lowest "Caused by" sections in the stack trace. In our case, it's:
Caused by: java.lang.NullPointerException <-...
Printing without newline (print 'a',) prints a space, how to remove?
...ts prints the same string. Note that it works for multiplication of any length string (e.g. 'foo' * 20 works).
>>> print 'a' * 20
aaaaaaaaaaaaaaaaaaaa
If you want to do this in general, build up a string and then print it once. This will consume a bit of memory for the string, but only m...
How to remove an element from a list by index
...
Use del and specify the index of the element you want to delete:
>>> a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> del a[-1]
>>> a
[0, 1, 2, 3, 4, 5, 6, 7, 8]
Also supports slices:
>>> del a[2:4]
>>> a
[0, 1, 4, 5, 6, 7, 8, 9]
Here is the section f...
How to use WHERE IN with Doctrine 2
...for a solution.
From the original post, the following line of code:
$qb->add('where', $qb->expr()->in('r.winner', array('?1')));
Wrapping the named parameter as an array causes the bound parameter number issue. By removing it from its array wrapping:
$qb->add('where', $qb->expr()...
Format a datetime into a string with milliseconds
... datetime
print datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3]
>>>> OUTPUT >>>>
2020-05-04 10:18:32.926
Note: For Python3, print requires parentheses:
print(datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3])
...
Find the similarity metric between two strings
...imilar(a, b):
return SequenceMatcher(None, a, b).ratio()
Using it:
>>> similar("Apple","Appel")
0.8
>>> similar("Apple","Mango")
0.0
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How to print SQL statement in codeigniter model
...
To display the query string:
print_r($this->db->last_query());
To display the query result:
print_r($query);
The Profiler Class will display benchmark results, queries you have run, and $_POST data at the bottom of your pages.
To enable the profiler pl...
Pythonic way to combine FOR loop and IF statement
... gen = (y for (x,y) in enumerate(xyz) if x not in a) returns >>> 12 when I type for x in gen: print x -- so why the unexpected behavior with enumerate?
– ChewyChunks
Aug 8 '11 at 12:40
...
How to convert a boolean array to an int array
...so you can add it to int arrays without having to explicitly convert it:
>>> x
array([ True, False, True], dtype=bool)
>>> x + [1, 2, 3]
array([2, 2, 4])
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Filtering a list based on a list of booleans
...
You're looking for itertools.compress:
>>> from itertools import compress
>>> list_a = [1, 2, 4, 6]
>>> fil = [True, False, True, False]
>>> list(compress(list_a, fil))
[1, 4]
Timing comparisons(py3.x):
>>> list_a = [...