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How to delete a row by reference in data.table?
...estion. data.table can't delete rows by reference yet.
data.table can add and delete columns by reference since it over-allocates the vector of column pointers, as you know. The plan is to do something similar for rows and allow fast insert and delete. A row delete would use memmove in C to budge u...
How do API Keys and Secret Keys work? Would it be secure if I have to pass my API and secret keys to
I am just starting to think about how api keys and secret keys work. Just 2 days ago I signed up for Amazon S3 and installed the S3Fox Plugin . They asked me for both my Access Key and Secret Access Key, both of which require me to login to access.
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How to replace captured groups only?
I have HTML code before and after the string:
5 Answers
5
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Is there a Python function to determine which quarter of the year a date is in?
...ed to count from 1 instead;-).
Originally two answers, multiply upvoted and even originally accepted (both currently deleted), were buggy -- not doing the -1 before the division, and dividing by 4 instead of 3. Since .month goes 1 to 12, it's easy to check for yourself what formula is right:
fo...
What is the fastest way to get the value of π?
... fastest π I know of is the one with the digits hard coded. Looking at Pi and Pi[PDF], there are a lot of formulae.
Here is a method that converges quickly — about 14 digits per iteration. PiFast, the current fastest application, uses this formula with the FFT. I'll just write the formula, since...
Looping through a hash, or using an array in PowerShell
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Christian's answer works well and shows how you can loop through each hash table item using the GetEnumerator method. You can also loop through using the keys property. Here is an example how:
$hash = @{
a = 1
b = 2
c = 3
}
$hash.Keys | % { "...
What is the difference between join and merge in Pandas?
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I always use join on indices:
import pandas as pd
left = pd.DataFrame({'key': ['foo', 'bar'], 'val': [1, 2]}).set_index('key')
right = pd.DataFrame({'key': ['foo', 'bar'], 'val': [4, 5]}).set_index('key')
left.join(right, lsuffix='_l', rsuffix='_r')
val_l ...
How can I declare and use Boolean variables in a shell script?
...s before the revision on Feb 12, 2014 pertain only to the original answer, and many of the comments are wrong when associated with the revised answer. For example, Dennis Williamson's comment about bash builtin true on Jun 2, 2010 only applies to the original answer, not the revised.
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How do I measure separate CPU core usage for a process?
...es shown by having that specific process run under a specific user account and use Type 'u' to limit to that user
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Why does a return in `finally` override `try`?
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@Castrohenge - it's not a hard and fast rule, but most of the copunter-examples in that thread are pretty contrived, and the only valid case I see is the "guard clause" (essentially the pattern of checking input data at the top of the function and returnin...