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Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...an work around it from within psql by executing the DDL statement conditionally:
SELECT 'CREATE DATABASE mydb'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'mydb')\gexec
The manual:
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's...
Continuously read from STDOUT of external process in Ruby
...iven by blender line by line to update a progress bar in a GUI. It's not really important that blender is the external process whose stdout I need to read.
...
Can dplyr package be used for conditional mutating?
...and the conditions (except for the default value of NA at the end) are mutually exclusive, as is the case in the question, then we can use an arithmetic expression such that each term is multiplied by the desired result using na_if at the end to replace 0 with NA.
df %>%
mutate(g = 2 * (a == 2 ...
What is the difference between range and xrange functions in Python 2.X?
...hey did. In Python 3. (They couldn't do that in the Python 2.x line, since all changes must be backwards compatible.)
– Paul Draper
May 7 '15 at 3:50
12
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Python matplotlib multiple bars
How to plot multiple bars in matplotlib, when I tried to call the bar function multiple times, they overlap and as seen the below figure the highest value red can be seen only.
How can I plot the multiple bars with dates on the x-axes?
...
Why does @foo.setter in Python not work for me?
...k with setters :-)
– Eenoku
Jun 12 '15 at 9:16
20
It works in python 3 because every class is a n...
How to extract the n-th elements from a list of tuples?
...
@Wayne Werner: Yep. This stuff was all just passive knowledge (I don't often use it) - but it's good to be reminded now and then so you know where / what to look for...
– Daren Thomas
Jul 22 '10 at 13:14
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Simple Digit Recognition OCR in OpenCV-Python
...stand some of the features at end)
2) Since I knew, without understanding all those features, it is difficult to do that method. I tried some other papers, but all were a little difficult for a beginner.
So I just decided to take all the pixel values as my features. (I was not worried about accura...
What's the difference between Git Revert, Checkout and Reset?
...the history.
git reset
This command is a little more complicated. It actually does a couple of different things depending on how it is invoked. It modifies the index (the so-called "staging area"). Or it changes which commit a branch head is currently pointing at. This command may alter existing h...
How to provide user name and password when connecting to a network share
...
151
You can either change the thread identity, or P/Invoke WNetAddConnection2. I prefer the latter...