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What does the caret operator (^) in Python do?
...y one) of the operands (evaluates to) true.
To demonstrate:
>>> 0^0
0
>>> 1^1
0
>>> 1^0
1
>>> 0^1
1
To explain one of your own examples:
>>> 8^3
11
Think about it this way:
1000 # 8 (binary)
0011 # 3 (binary)
---- # APPLY XOR ('vertically')
10...
How do I create test and train samples from one dataframe with pandas?
...ering how I would be able to split the dataframe into two random samples (80% and 20%) for training and testing.
23 Answers...
How to add leading zeros?
...f digits to begin with, so let's try a harder example of making powers of 10 width 8 too.
anim <- 25499:25504
x <- 10 ^ (0:5)
paste (and it's variant paste0) are often the first string manipulation functions that you come across. They aren't really designed for manipulating numbers, but ...
MySQL - Rows to Columns
...temvalue |
+--------+----------+-----------+
| 1 | A | 10 |
| 1 | B | 3 |
| 2 | A | 9 |
| 2 | C | 40 |
+--------+----------+-----------+
This will be our goal, the pretty pivot table:
select * from history_itemvalue_piv...
Code Golf: Collatz Conjecture
Inspired by http://xkcd.com/710/ here is a code golf for it.
70 Answers
70
...
How to write a cron that will run a script every day at midnight?
...how to use it on Ubuntu. Your crontab line will look something like this:
00 00 * * * ruby path/to/your/script.rb
(00 00 indicates midnight--0 minutes and 0 hours--and the *s mean every day of every month.)
Syntax:
mm hh dd mt wd command
mm minute 0-59
hh hour 0-23
dd day of month 1-...
How can I perform a culture-sensitive “starts-with” operation from the middle of a string?
...
+100
I'll consider the problem of many<->one/many casemappings first and separately from handling different Normalization forms.
Fo...
An efficient way to transpose a file in Bash
..." "a[i,j];
}
print str
}
}' file
output
$ more file
0 1 2
3 4 5
6 7 8
9 10 11
$ ./shell.sh
0 3 6 9
1 4 7 10
2 5 8 11
Performance against Perl solution by Jonathan on a 10000 lines file
$ head -5 file
1 0 1 2
2 3 4 5
3 6 7 8
4 9 10 11
1 0 1 2
$ wc -l < file
10000
$ ti...
How to print a percentage value in python?
...supports a percentage floating point precision type:
>>> print "{0:.0%}".format(1./3)
33%
If you don't want integer division, you can import Python3's division from __future__:
>>> from __future__ import division
>>> 1 / 3
0.3333333333333333
# The above 33% example wo...