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Are list-comprehensions and functional functions faster than “for loops”?
...in range(10)]`>)
1 0 BUILD_LIST 0
3 LOAD_FAST 0 (.0)
>> 6 FOR_ITER 12 (to 21)
9 STORE_FAST 1 (x)
12 LOAD_FAST 1 (x)
15 LIST_APPEND 2
...
How to add a new row to an empty numpy array
...
237
The way to "start" the array that you want is:
arr = np.empty((0,3), int)
Which is an empty ...
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 ...
Center a column using Twitter Bootstrap 3
...f one column size within the container (12 columns) in Twitter Bootstrap 3 ?
34 Answers
...
How do you extract a column from a multi-dimensional array?
...
234
>>> import numpy as np
>>> A = np.array([[1,2,3,4],[5,6,7,8]])
>>> ...
Is Integer Immutable
... |
edited Oct 2 '19 at 18:37
answered Apr 6 '11 at 0:35
Tra...
Create numpy matrix filled with NaNs
...ed array and assign to all entries at once:
>>> a = numpy.empty((3,3,))
>>> a[:] = numpy.nan
>>> a
array([[ NaN, NaN, NaN],
[ NaN, NaN, NaN],
[ NaN, NaN, NaN]])
I have timed the alternatives a[:] = numpy.nan here and a.fill(numpy.nan) as posted by ...
Fast check for NaN in NumPy
...hine it is about 2.5x faster to use numpy.sum in place of numpy.min:
In [13]: %timeit np.isnan(np.min(x))
1000 loops, best of 3: 244 us per loop
In [14]: %timeit np.isnan(np.sum(x))
10000 loops, best of 3: 97.3 us per loop
Unlike min, sum doesn't require branching, which on modern hardware tends...
Is there a foreach in MATLAB? If so, how does it behave if the underlying data changes?
...in other languages. This means that the following code always prints 1, 2, 3, 4, 5 regardless of the value of B.
A = 1:5;
for i = A
A = B;
disp(i);
end
If you want to be able to respond to changes in the data structure during iterations, a WHILE loop may be more appropriate --- you'll be...
Get integer value from string in swift
...ft 2.0 you can initialize Integer using constructor
var stringNumber = "1234"
var numberFromString = Int(stringNumber)
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