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Why does the is operator return false when given null?
...ers. The question that the is operator answers is the third question. y is X does not ask "is y a legal value of a variable of type X?" It asks "Is y a valid reference to an object of type X?" Since a null reference is not a valid reference to any object of any type, the answer is "no". That drivewa...
unbound method f() must be called with fibo_ instance as first argument (got classobj instance inste
... are calling the method on the class rather than on an instance, which is exactly what was happening in this case because you hadn't instantiated the class.
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Is it possible to modify variable in python that is in outer, but not global, scope?
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Python 3.x has the nonlocal keyword. I think this does what you want, but I'm not sure if you are running python 2 or 3.
The nonlocal statement causes the listed identifiers to refer to
previously bound variables in the nearest...
ggplot2 keep unused levels barplot
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You need to set drop=FALSE on both scales (fill and x) like this:
library(ggplot2)
df <- data.frame(type=c("A", "A", "A", "B", "B"), group=rep("group1", 5))
df1 <- data.frame(type=c("A", "A", "A", "B", "B", "A", "A", "C", "B", "B"), group=c(rep("group1", 5),rep("group2"...
enum - getting value of enum on string conversion
...bject. Use the .value attribute if you wanted just to print that:
print(D.x.value)
See the Programmatic access to enumeration members and their attributes section:
If you have an enum member and need its name or value:
>>>
>>> member = Color.red
>>> member.name
're...
How to join (merge) data frames (inner, outer, left, right)
...its optional parameters:
Inner join: merge(df1, df2) will work for these examples because R automatically joins the frames by common variable names, but you would most likely want to specify merge(df1, df2, by = "CustomerId") to make sure that you were matching on only the fields you desired. You ...
How to replace a hash key with another key
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At last! This is exactly what I searched!
– TiSer
Sep 30 '16 at 8:23
4
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Does Python optimize tail recursion?
...ng to transform it like that - just: from operator import add; reduce(add, xrange(n + 1), csum) ?
– Jon Clements♦
Nov 27 '12 at 20:10
38
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How to delete files older than X hours
...wered Oct 30 '08 at 8:39
Paul DixonPaul Dixon
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Extract subset of key-value pairs from Python dictionary object?
...u're using Python 3, and you only want keys in the new dict that actually exist in the original one, you can use the fact to view objects implement some set operations:
{k: bigdict[k] for k in bigdict.keys() & {'l', 'm', 'n'}}
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