大约有 5,100 项符合查询结果（耗时：0.0288秒） [XML]
Delete rows from a pandas DataFrame based on a conditional expression involving len(string) giving K
... end with some profiling stats on why @User's drop solution is slower than raw column based filtration:-
%timeit df_new = df[(df.E>0)]
345 µs ± 10.5 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
%timeit dft.drop(dft[dft.E < 0].index, inplace=True)
890 µs ± 94.9 µs per loo...
How can I rename a database column in a Ruby on Rails migration?
...nd doing one row at a time. The migration would execute much faster with raw sql statements to update correctly named columns. For example, in the first db migration script, after adding the duplicate column names, execute "Update table_name set correct_name_column_one = old_name_column_one"
...
Python multiprocessing PicklingError: Can't pickle
...ol(processes=5)
# asyn execution of lambda
jobs = []
for i in range(10):
job = apply_async(pool, lambda a, b: (a, b, a * b), (i, i + 1))
jobs.append(job)
for job in jobs:
print job.get()
print
# async execution of static method
class O(object):...
Are Javascript arrays sparse?
...s like reduce(), Math.max(), and "for ... of" will walk through the entire range of possible integer indices form 0 to the length, visiting many that return 'undefined'. BUT 'for ... in' loops might do as you expect, visiting only the defined keys.
Here's an example using Node.js:
"use strict";
c...
C++ map access discards qualifiers (const)
...) for std::map. If element doesn't exist the function throws a std::out_of_range exception, in contrast to operator [].
share
|
improve this answer
|
follow
|
...
Is BCrypt a good hashing algorithm to use in C#? Where can I find it? [closed]
...d all the bcrypt hashed passwords to the new hashes? Wouldnt they need the raw passwords to hash it using the new algorithm?
– Dharmendar Kumar 'DK'
Jan 6 '14 at 22:44
8
...
best way to preserve numpy arrays on disk
...Not that random data
data['semi-random'] = np.zeros((size, size))
for i in range(size):
for j in range(size):
data['semi-random'][i,j] = np.sum(data['random'][i,:]) + np.sum(data['random'][:,j])
# Not random data
data['not-random'] = np.arange( size*size, dtype=np.float64 ).reshape( (si...
Concatenating two one-dimensional NumPy arrays
...
],
labels=["r_", "stack+reshape", "hstack", "concatenate"],
n_range=[2 ** k for k in range(19)],
xlabel="len(a)",
)
share
|
improve this answer
|
follow
...
How to create a trie in Python
... may take up to 50x-100x less memory than
in a standard Python dict; the raw lookup speed is comparable; trie
also provides fast advanced methods like prefix search.
Based on marisa-trie C++ library.
Here's a blog post from a company using marisa trie successfully:
https://www.repustate.c...
Extract a substring from a string in Ruby using a regular expression
...an array of the captures
matchdata.captures # ["ants","pants"]
# Or use raw indices
matchdata[0] # whole regex match: "<ants> <pants>"
matchdata[1] # first capture: "ants"
matchdata[2] # second capture: "pants"
...