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Is Big O(logn) log base e?
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edited Feb 15 '10 at 5:23
community wiki
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Any reason not to use '+' to concatenate two strings?
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122
There is nothing wrong in concatenating two strings with +. Indeed it's easier to read than ''...
Pandas conditional creation of a series/dataframe column
...', 'green', 'red')
print(df)
yields
Set Type color
0 Z A green
1 Z B green
2 X B red
3 Y C red
If you have more than two conditions then use np.select. For example, if you want color to be
yellow when (df['Set'] == 'Z') & (df['Type'] == 'A')
otherwise blu...
Convert a float64 to an int in Go
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213
package main
import "fmt"
func main() {
var x float64 = 5.7
var y int = int(x)
fmt.Printl...
Rotating x axis labels in R for barplot
...xaxt="n")
labs <- paste(names(table(mtcars$cyl)), "cylinders")
text(cex=1, x=x-.25, y=-1.25, labs, xpd=TRUE, srt=45)
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MySQL ON vs USING?
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415
It is mostly syntactic sugar, but a couple differences are noteworthy:
ON is the more general ...
Using try vs if in python
...surements:
>>> import timeit
>>> timeit.timeit(setup="a=1;b=1", stmt="a/b") # no error checking
0.06379691968322732
>>> timeit.timeit(setup="a=1;b=1", stmt="try:\n a/b\nexcept ZeroDivisionError:\n pass")
0.0829463709378615
>>> timeit.timeit(setup="a=1;b=0", stmt=...
Is there a “not equal” operator in Python?
...ect identities, you can use the keyword is and its negation is not.
e.g.
1 == 1 # -> True
1 != 1 # -> False
[] is [] #-> False (distinct objects)
a = b = []; a is b # -> True (same object)
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Why is the order in dictionaries and sets arbitrary?
...and lets assume the table size is 8 slots. In Python 2.7, hash('foo') is -4177197833195190597, hash('bar') is 327024216814240868. Modulo 8, that means these two keys are slotted in slots 3 and 4 then:
>>> hash('foo')
-4177197833195190597
>>> hash('foo') % 8
3
>>> hash('ba...
Is Redis just a cache?
...c increment command. Something like this -
$ HINCRBY unique_ids question 1
(integer) 1
$ HMSET question:1 title "Is Redis just a cache?" asked_by 12 votes 0
OK
$ HINCRBY unique_ids answer 1
(integer) 1
$ HMSET answer:1 question_id 1 answer_text "No, its a lot more" answered_by 15 votes 1
OK
Han...