大约有 43,000 项符合查询结果（耗时：0.0631秒） [XML]
What's the fastest way to merge/join data.frames in R?
...he plyr timings here. Also note that the data.table do include the time to convert to data.table and set the key, for fareness.
This answer has been updated since originally answered in Dec 2010. The previous benchmark results are below. Please see revision history of this answer to see what chan...
Build fat static library (device + simulator) using Xcode and SDK 4+
...ary takes much more effort to setup, but much nicer long-term solution (it converts your library into a Framework).
Use this, then tweak it to add support for Archive builds - c.f. @Frederik's comment below on the changes he's using to make this work nicely with Archive mode.
RECENT CHANGES:
1. ...
Get a substring of a char* [duplicate]
...is will waste memory. You have been warned! :P
– alexandernst
Nov 11 '13 at 19:00
23
@alexanderns...
Android dismiss keyboard
...nswered Aug 24 '10 at 5:38
DeRaganDeRagan
21.4k66 gold badges3737 silver badges4949 bronze badges
...
What is “entropy and information gain”?
...-1)/2) = prob_array(diff+(array_size-1)/2) + 1
endif
endfor
//Convert values in prob_array to probabilities and compute entropy
n = total(prob_array)
entrop = 0
for i = 0, array_size-1 do begin
prob_array(i) = prob_array(i)/n
//Base 2 log of x is Ln(x)/Ln(2). Take Ln of array ...
Modify table: How to change 'Allow Nulls' attribute from not null to allow null
... then you will need to perform separate ALTER TABLE .. ALTER COLUMN .. commands
– sonyisda1
Feb 17 '17 at 15:14
...
How to remove leading zeros from alphanumeric text?
... "]");
}
See also
regular-expressions.info
repetitions, lookarounds, and anchors
String.replaceFirst(String regex)
share
|
improve this answer
|
follow
...
Remove all whitespaces from NSString
...stringByTrimmingCharactersInSet only removes characters from the beginning and the end of the string, not the ones in the middle.
1) If you need to remove only a given character (say the space character) from your string, use:
[yourString stringByReplacingOccurrencesOfString:@" " withString:@""]
...
Auto increment in phpmyadmin
I have an existing database using PHP, MySQL and phpMyAdmin.
9 Answers
9
...
C# Double - ToString() formatting with two decimal places but no rounding
...te(myDoubleValue * 100) / 100;
For instance:
If the number is 50.947563 and you use the following, the following will happen:
- Math.Truncate(50.947563 * 100) / 100;
- Math.Truncate(5094.7563) / 100;
- 5094 / 100
- 50.94
And there's your answer truncated, now to format the string simply do the...