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Resetting generator object in Python
...rsion of your generator:
y = FunctionWithYield()
y, y_backup = tee(y)
for x in y:
print(x)
for x in y_backup:
print(x)
This could be beneficial from memory usage point of view if the original iteration might not process all the items.
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Extracting the last n characters from a string in R
...'s straight-forward to make a function to do this using substr and nchar:
x <- "some text in a string"
substrRight <- function(x, n){
substr(x, nchar(x)-n+1, nchar(x))
}
substrRight(x, 6)
[1] "string"
substrRight(x, 8)
[1] "a string"
This is vectorised, as @mdsumner points out. Cons...
Group By Multiple Columns
...
Use an anonymous type.
Eg
group x by new { x.Column1, x.Column2 }
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Replacements for switch statement in Python?
I want to write a function in Python that returns different fixed values based on the value of an input index.
44 Answers...
SQL is null and = null [duplicate]
...t on rows by coding where my_column = null.
SQL provides the special syntax for testing if a column is null, via is null and is not null, which is a special condition to test for a null (or not a null).
Here's some SQL showing a variety of conditions and and their effect as per above.
create tabl...
Standardize data columns in R
I have a dataset called spam which contains 58 columns and approximately 3500 rows of data related to spam messages.
15 ...
How to remove all whitespace from a string?
So " xx yy 11 22 33 " will become "xxyy112233" . How can I achieve this?
9 Answers
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How to check if all elements of a list matches a condition?
...which is the builtin for this situation. We combine this with a generator expression to produce the result you want cleanly and efficiently. For example:
>>> items = [[1, 2, 0], [1, 2, 0], [1, 2, 0]]
>>> all(flag == 0 for (_, _, flag) in items)
True
>>> items = [[1, 2, 0]...
Suppress/ print without b' prefix for bytes in Python 3
... is to manually slice off the b'' from the resulting repr():
>>> x = b'\x01\x02\x03\x04'
>>> print(repr(x))
b'\x01\x02\x03\x04'
>>> print(repr(x)[2:-1])
\x01\x02\x03\x04
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Is there a numpy builtin to reject outliers from a list
...a)] TypeError: only integer scalar arrays can be converted to a scalar index OR it just freezes my program
– john ktejik
Sep 16 '17 at 22:26
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