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Principal component analysis in Python
...
Months later, here's a small class PCA, and a picture:
#!/usr/bin/env python
""" a small class for Principal Component Analysis
Usage:
p = PCA( A, fraction=0.90 )
In:
A: an array of e.g. 1000 observations x 20 variables, 1000 rows x 20 colum...
How to get the start time of a long-running Linux process?
... like this command:
ps -eo pid,lstart,cmd
The above command will output all processes, with formatters to get PID, command run, and date+time started.
Example (from Debian/Jessie command line)
$ ps -eo pid,lstart,cmd
PID CMD STARTED
1 Tue Jun 7 01...
LINQ: “contains” and a Lambda query
I have a List<BuildingStatus> called buildingStatus . I'd like to check whether it contains a status whose char code (returned by GetCharCode() ) equals some variable, v.Status .
...
How do you disable the unused variable warnings coming out of gcc in 3rd party code I do not wish to
I'd like to know what switch you pass to the gcc compiler to turn off unused variable warnings? I'm getting errors out of boost on windows and I do not want to touch the boost code:
...
Odd behavior when Java converts int to byte?
...+ unsignedByte);
Would print out: "Signed: -1 Unsigned: 255"
What's actually happening here?
We are using bitwise AND to mask all of the extraneous sign bits (the 1's to the left of the least significant 8 bits.)
When an int is converted into a byte, Java chops-off the left-most 24 bits
111111...
Structure padding and packing
....
A note though - unaligned memory access is slower on architectures that allow it (like x86 and amd64), and is explicitly prohibited on strict alignment architectures like SPARC.
share
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improve t...
Save PL/pgSQL output from PostgreSQL to a CSV file
...e to your local PC. It also needs to be run as a Postgres "superuser" (normally called "root") because Postgres can't stop it doing nasty things with that machine's local filesystem.
That doesn't actually mean you have to be connected as a superuser (automating that would be a security risk of a di...
String concatenation in Ruby
...ficient in term of memory/speed from what I've seen (not measured though). All three methods will throw an uninitialized constant error when ROOT_DIR is nil.
When dealing with pathnames, you may want to use File.join to avoid messing up with pathname separator.
In the end, it is a matter of taste....
How do I add custom field to Python log format string?
...LoggerAdapter so you don't have to pass the extra info with every logging call:
import logging
extra = {'app_name':'Super App'}
logger = logging.getLogger(__name__)
syslog = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s %(app_name)s : %(message)s')
syslog.setFormatter(formatte...
How to see log files in MySQL?
I've read that Mysql server creates a log file where it keeps a record of all activities - like when and what queries execute.
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