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Postgresql - unable to drop database because of some auto connections to DB
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(and possibly other users/roles; see \l+ in psql)
You can then terminate all connections to this db except your own:
SELECT pid, pg_terminate_backend(pid)
FROM pg_stat_activity
WHERE datname = current_database() AND pid <> pg_backend_pid();
On older versions pid was called procpid so you'...
count the frequency that a value occurs in a dataframe column
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If you want to apply to all columns you can use:
df.apply(pd.value_counts)
This will apply a column based aggregation function (in this case value_counts) to each of the columns.
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What are the differences between Deferred, Promise and Future in JavaScript?
...the differences between Deferreds, Promises and Futures?
Is there a generally approved theory behind all these three?
5 A...
Get last field using awk substr
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this worked for me when receiving from piped input. Totally forgot about perl.
– Chris
May 23 '18 at 21:46
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Remove columns from dataframe where ALL values are NA
I'm having trouble with a data frame and couldn't really resolve that issue myself:
The dataframe has arbitrary properties as columns and each row represents one data set .
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How to convert C# nullable int to int
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The other answers so far are all correct; I just wanted to add one more that's slightly cleaner:
v2 = v1 ?? default(int);
Any Nullable<T> is implicitly convertible to its T, PROVIDED that the entire expression being evaluated can never result in...
How to delete/create databases in Neo4j?
...s in the graph database Neo4j like in MySQL? Or, at least, how to delete all nodes and relationships of an existing graph to get a clean setup for tests, e.g., using shell commands similar to rmrel or rm ?
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Regex using javascript to return just numbers
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All arrays are objects though, no?
– meder omuraliev
Dec 5 '12 at 23:18
6
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Python - Create list with numbers between 2 values?
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Use range. In Python 2.x it returns a list so all you need is:
>>> range(11, 17)
[11, 12, 13, 14, 15, 16]
In Python 3.x range is a iterator. So, you need to convert it to a list:
>>> list(range(11, 17))
[11, 12, 13, 14, 15, 16]
Note: The second nu...
How to zero pad a sequence of integers in bash so that all have the same width?
...uce the following output:
00010
00011
00012
00013
00014
00015
More generally, bash has printf as a built-in so you can pad output with zeroes as follows:
$ i=99
$ printf "%05d\n" $i
00099
You can use the -v flag to store the output in another variable:
$ i=99
$ printf -v j "%05d" $i
$ echo $j...