大约有 46,000 项符合查询结果（耗时：0.0213秒） [XML]
Ruby Hash to array of values
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Ray ToalRay Toal
76.4k1212 gold badges143143 silver badges204204 bronze badges
3
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Split column at delimiter in data frame [duplicate]
...me.
I added a "x|y" line to avoid ambiguities:
df <- data.frame(ID=11:13, FOO=c('a|b','b|c','x|y'))
foo <- data.frame(do.call('rbind', strsplit(as.character(df$FOO),'|',fixed=TRUE)))
Or, if you want to replace the columns in the existing data.frame:
within(df, FOO<-data.frame(do.call('r...
NameError: global name 'xrange' is not defined in Python 3
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You are trying to run a Python 2 codebase with Python 3. xrange() was renamed to range() in Python 3.
Run the game with Python 2 instead. Don't try to port it unless you know what you are doing, most likely there will be more problems beyond xrange() vs. range().
For the recor...
NameError: global name 'unicode' is not defined - in Python 3
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Python 3 renamed the unicode type to str, the old str type has been replaced by bytes.
if isinstance(unicode_or_str, str):
text = unicode_or_str
decoded = False
else:
text = unicode_or_str.decode(encoding)
decoded =...
rspec 3 - stub a class method
I am upgrading from rspec 2.99 to rspec 3.0.3 and have converted instance methods to use allow_any_instance_of , but haven't figured out how to stub a class method. I have code like this:
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Looping over a list in Python
...with sublists in it. I want to print all the sublists with length equal to 3.
4 Answers
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Struct inheritance in C++
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answered Jun 11 '09 at 3:44
Alex MartelliAlex Martelli
724k148148 gold badges11261126 silver badges13241324 bronze badges
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Python - abs vs fabs
...(-2))
Out[7]: int
In [8]: type(abs(-2.0))
Out[8]: float
In [9]: type(abs(3+4j))
Out[9]: float
In [10]: type(math.fabs(-2))
Out[10]: float
In [11]: type(math.fabs(-2.0))
Out[11]: float
In [12]: type(math.fabs(3+4j))
---------------------------------------------------------------------------
Type...
dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
....drop argument that does just what you asked for:
df = data.frame(a=rep(1:3,4), b=rep(1:2,6))
df$b = factor(df$b, levels=1:3)
df %>%
group_by(b, .drop=FALSE) %>%
summarise(count_a=length(a))
#> # A tibble: 3 x 2
#> b count_a
#> <fct> <int>
#> 1 1 ...
Why is conversion from string constant to 'char*' valid in C but invalid in C++
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3 Answers
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