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Get average color of image via Javascript
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edited Dec 19 '17 at 10:12
Aprillion
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answer...
Remove a folder from git tracking
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10
I know this is an old thread but I just wanted to add a little as the marked solution didn't so...
Storing sex (gender) in database
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answered Nov 14 '10 at 2:29
OMG PoniesOMG Ponies
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Setup RSpec to test a gem (not Rails)
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answered Dec 9 '10 at 19:23
iainiain
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What does $(function() {} ); do?
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Chris HasińskiChris Hasiński
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add a co...
What is causing this ActiveRecord::ReadOnlyRecord error?
...s 2.3.4 and above
Most of the above no longer holds true, after September 10 2012:
using Record.find_by_sql is a viable option
:readonly => true is automatically inferred only if :joins was specified without an explicit :select nor an explicit (or finder-scope-inherited) :readonly option (see ...
Why is Python 3.x's super() magic?
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edited Feb 10 '18 at 18:27
answered Oct 26 '13 at 16:41
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Applying function with multiple arguments to create a new pandas column
...on:
>>> import numpy as np
>>> df = pd.DataFrame({"A": [10,20,30], "B": [20, 30, 10]})
>>> df['new_column'] = np.multiply(df['A'], df['B'])
>>> df
A B new_column
0 10 20 200
1 20 30 600
2 30 10 300
or vectorize arbitrary fun...
Drop data frame columns by name
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You can use a simple list of names :
DF <- data.frame(
x=1:10,
y=10:1,
z=rep(5,10),
a=11:20
)
drops <- c("x","z")
DF[ , !(names(DF) %in% drops)]
Or, alternatively, you can make a list of those to keep and refer to them by name :
keeps <- c("y", "a")
DF[keeps]
EDIT :
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How to speed up insertion performance in PostgreSQL
... storage, stop now. Back your data up, restructure your RAID array to RAID 10, and try again. RAID 5/6 are hopeless for bulk write performance - though a good RAID controller with a big cache can help.
If you have the option of using a hardware RAID controller with a big battery-backed write-back ca...