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Using async/await for multiple tasks
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591
int[] ids = new[] { 1, 2, 3, 4, 5 };
Parallel.ForEach(ids, i => DoSomething(1, i, blogClient)...
Efficient way to apply multiple filters to pandas DataFrame or Series
...numpy) allow for boolean indexing, which will be much more efficient:
In [11]: df.loc[df['col1'] >= 1, 'col1']
Out[11]:
1 1
2 2
Name: col1
In [12]: df[df['col1'] >= 1]
Out[12]:
col1 col2
1 1 11
2 2 12
In [13]: df[(df['col1'] >= 1) & (df['col1'] <=1 )]
Out...
How to concatenate twice with the C preprocessor and expand a macro as in “arg ## _ ## MACRO”?
...EVALUATOR(fun, VARIABLE)
extern void NAME(mine)(char *x);
$ gcc -E xx.c
# 1 "xx.c"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "xx.c"
extern void mine_3(char *x);
$
Two levels of indirection
In a comment to another answer, Cade Roux asked why this needs two levels of indirection. ...
Mean per group in a data.frame [duplicate]
...aggregate was designed for:
d <- read.table(text=
'Name Month Rate1 Rate2
Aira 1 12 23
Aira 2 18 73
Aira 3 19 45
Ben 1 53 19
Ben 2 22 87
Ben 3 19 45
Cat 1 22 ...
Remove all occurrences of a value from a list?
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Functional approach:
Python 3.x
>>> x = [1,2,3,2,2,2,3,4]
>>> list(filter((2).__ne__, x))
[1, 3, 3, 4]
or
>>> x = [1,2,3,2,2,2,3,4]
>>> list(filter(lambda a: a != 2, x))
[1, 3, 3, 4]
Python 2.x
>>> x = [1,2,3,2,2,2,3,4]
>...
How do you know when to use fold-left and when to use fold-right?
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105
You can transfer a fold into an infix operator notation (writing in between):
This example fo...
Difference between numpy.array shape (R, 1) and (R,)
In numpy , some of the operations return in shape (R, 1) but some return (R,) . This will make matrix multiplication more tedious since explicit reshape is required. For example, given a matrix M , if we want to do numpy.dot(M[:,0], numpy.ones((1, R))) where R is the number of rows (of co...
`elif` in list comprehension conditionals
...essions were designed exactly for this sort of use-case:
>>> l = [1, 2, 3, 4, 5]
>>> ['yes' if v == 1 else 'no' if v == 2 else 'idle' for v in l]
['yes', 'no', 'idle', 'idle', 'idle']
Hope this helps :-)
s...
Splitting a list into N parts of approximately equal length
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Grep regex NOT containing string
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351
grep matches, grep -v does the inverse. If you need to "match A but not B" you usually use pipes...