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Numbering rows within groups in a data frame
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284
Use ave, ddply, dplyr or data.table:
df$num <- ave(df$val, df$cat, FUN = seq_along)
or:
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Is it possible to use 'else' in a list comprehension? [duplicate]
... c. It can be used in comprehension statements:
>>> [a if a else 2 for a in [0,1,0,3]]
[2, 1, 2, 3]
So for your example,
table = ''.join(chr(index) if index in ords_to_keep else replace_with
for index in xrange(15))
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How to split a string in shell and get the last field
Suppose I have the string 1:2:3:4:5 and I want to get its last field ( 5 in this case). How do I do that using Bash? I tried cut , but I don't know how to specify the last field with -f .
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get list of pandas dataframe columns based on data type
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What is the difference between String.slice and String.substring?
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882
slice() works like substring() with a few different behaviors.
Syntax: string.slice(start, stop...
How do I check if a string is unicode or ascii?
...Unicode characters. There is a bytes type that holds raw bytes.
In Python 2, a string may be of type str or of type unicode. You can tell which using code something like this:
def whatisthis(s):
if isinstance(s, str):
print "ordinary string"
elif isinstance(s, unicode):
pri...
Check if all elements in a list are identical
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C++ preprocessor __VA_ARGS__ number of arguments
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Regular Expression to reformat a US phone number in Javascript
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How do I replace NA values with zeros in an R dataframe?
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