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Numbering rows within groups in a data frame
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answered Oct 16 '12 at 23:41
mnelmnel
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ADT requires 'org.eclipse.wst.sse.core 0.0.0' but it could not be found
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I've just encountered exactly the same problem in Eclipse 3.6 (Helios). After plenty of Googling I came across this link:
http://code.google.com/intl/es/eclipse/docs/faq.html#wstinstallerror
During installation, there's an error
about requiring
org.eclipse.wst.sse.ui. How d...
What does the 'b' character do in front of a string literal?
... it indicates that the
literal should become a bytes literal
in Python 3 (e.g. when code is
automatically converted with 2to3). A
'u' or 'b' prefix may be followed by
an 'r' prefix.
The Python 3 documentation states:
Bytes literals are always prefixed with 'b' or 'B'; they produce an...
Why isn't String.Empty a constant?
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edited Feb 3 '09 at 17:31
answered Feb 3 '09 at 17:24
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Pelican 3.3 pelican-quickstart error “ValueError: unknown locale: UTF-8”
When I was trying to use pelican3.3, I typed the commend "pelican-quickstart", some errors showed up.
6 Answers
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Numpy: Get random set of rows from 2D array
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>>> A = np.random.randint(5, size=(10,3))
>>> A
array([[1, 3, 0],
[3, 2, 0],
[0, 2, 1],
[1, 1, 4],
[3, 2, 2],
[0, 1, 0],
[1, 3, 1],
[0, 4, 1],
[2, 4, 2],
[3, 3, 1]])
>>> idx = np.ran...
The modulo operation on negative numbers in Python
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134
Unlike C or C++, Python's modulo operator (%) always return a number having the same sign as th...
Python String and Integer concatenation [duplicate]
...kticks) is deprecated in later versions of Python 2, and removed in Python 3. Use the str() function instead.
You can use :
string = 'string'
for i in range(11):
string +=`i`
print string
It will print string012345678910.
To get string0, string1 ..... string10 you can use this as @YOU suggeste...
Dynamically select data frame columns using $ and a character value
... a reproducible example below:
# set seed for reproducibility
set.seed(123)
df <- data.frame( col1 = sample(5,10,repl=T) , col2 = sample(5,10,repl=T) , col3 = sample(5,10,repl=T) )
# We want to sort by 'col3' then by 'col1'
sort_list <- c("col3","col1")
# Use 'do.call' to call order. Sec...
How to remove last n characters from every element in the R vector
...rame("data"=char_array,"data2"=1:4)
a$data = substr(a$data,1,nchar(a$data)-3)
a should now contain:
data data2
1 foo_ 1
2 bar_ 2
3 ap 3
4 b 4
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