大约有 6,000 项符合查询结果（耗时：0.0451秒） [XML]
Checking if a string can be converted to float in Python
... ------------
print(isfloat("")) False
print(isfloat("1234567")) True
print(isfloat("NaN")) True nan is also float
print(isfloat("NaNananana BATMAN")) False
print(isfloat("123.456")) True
print(isfloat("123.E4")) ...
What does the “yield” keyword do?
...one, etc. And generators return... well that's where yield comes in:
def f123():
yield 1
yield 2
yield 3
for item in f123():
print item
Instead of yield statements, if you had three return statements in f123() only the first would get executed, and the function would exit. But f1...
How to move a file?
I looked into the Python os interface, but was unable to locate a method to move a file. How would I do the equivalent of $ mv ... in Python?
...
How to retrieve a module's path?
...tually give you the path to the .pyc file that was loaded, at least on Mac OS X. So I guess you can do:
import os
path = os.path.abspath(a_module.__file__)
You can also try:
path = os.path.dirname(a_module.__file__)
To get the module's directory.
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Dynamic SQL - EXEC(@SQL) versus EXEC SP_EXECUTESQL(@SQL)
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EXEC('SELECT * FROM FOO WHERE ID=?', 123) will replace the parameter placeholder "?" with the value 123 and then execute the query, returning a result for SELECT * FROM FOO WHERE ID=123
– Peter Wone
Jun 1 '10 at 23:27
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sed: print only matching group
...it with a 2nd grep.
# To extract \1 from /xx([0-9]+)yy/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'xx[0-9]+yy' | grep -Eo '[0-9]+'
123
4
# To extract \1 from /a([0-9]+)b/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'a[0-9]+b' | grep -Eo '[0-9]+'
678
9
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Using Python's os.path, how do I go up one directory?
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os.path.abspath(os.path.join(os.path.dirname( __file__ ), '..', 'templates'))
As far as where the templates folder should go, I don't know since Django 1.4 just came out and I haven't looked at it yet. You should probably a...
What is the iPad user agent?
From what I gather, the iPad is using iPhone OS, but with a different screen resolution from the iPhone and iPod touch. So many sites may have to change their user agent detection to adapt to the iPad.
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Getting file size in Python? [duplicate]
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Use os.path.getsize(path) which will
Return the size, in bytes, of path. Raise OSError if the file does not exist or is inaccessible.
import os
os.path.getsize('C:\\Python27\\Lib\\genericpath.py')
Or use os.stat(path).st_...
module.exports vs exports in Node.js
...:
var x = require('file1.js');
contents of file1.js:
module.exports = '123';
When the above statement is executed, a Module object is created. Its constructor function is:
function Module(id, parent) {
this.id = id;
this.exports = {};
this.parent = parent;
if (parent &&...