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Boolean operators && and ||
...an return a vector, like this:
((-2:2) >= 0) & ((-2:2) <= 0)
# [1] FALSE FALSE TRUE FALSE FALSE
The longer form evaluates left to right examining only the first element of each vector, so the above gives
((-2:2) >= 0) && ((-2:2) <= 0)
# [1] FALSE
As the help page says...
How do I achieve the theoretical maximum of 4 FLOPs per cycle?
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+150
I've done this exact task before. But it was mainly to measure power consumption and CPU temperatures. The following code (which is ...
Disable migrations when running unit tests in Django 1.7
Django 1.7 introduced database migrations .
7 Answers
7
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Get index of array element faster than O(n)
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118
Convert the array into a hash. Then look for the key.
array = ['a', 'b', 'c']
hash = Hash[arr...
Aggregate / summarize multiple variables per group (e.g. sum, mean)
...he reshape2 package for this task:
require(reshape2)
df_melt <- melt(df1, id = c("date", "year", "month"))
dcast(df_melt, year + month ~ variable, sum)
# year month x1 x2
1 2000 1 -80.83405 -224.9540159
2 2000 2 -223.76331 -288.2418017
3 2000 3 -188.83930 -481....
Command-line Unix ASCII-based charting / plotting tool
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12 Answers
12
Active
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Python assigning multiple variables to same value? list behavior
... and Chris Wallace have a hot dog. If you change the first element of a to 1, the first elements of b and c are 1.
If you want to know if two names are naming the same object, use the is operator:
>>> a=b=c=[0,3,5]
>>> a is b
True
You then ask:
what is different from this...
How to scale down a range of numbers with a known min and max value
...anel. I want the height and width of each ellipse to be in a range of say 1-30. I have methods that find the minimum and maximum values from my data set, but I won't have the min and max until runtime. Is there an easy way to do this?
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