大约有 33,000 项符合查询结果（耗时：0.0377秒） [XML]
How do I replace NA values with zeros in an R dataframe?
...then assign it to the location/name on the left. In this case, we aren't really "doing" anything - just making zeroes. The left side is saying: look at the d object, inside the d object (the square brackets), find all the elements that return TRUE (is.na(d) returns a logical for each element). Once...
Changing all files' extensions in a folder with one command on Windows
...ropriate extensions. It will change from XXX to YYY. If you want to change all extensions, just use the wildcard again:
ren *.* *.YYY
One way to make this work recursively is with the FOR command. It can be used with the /R option to recursively apply a command to matching files. For example:
fo...
How to remove all MySQL tables from the command-line without DROP database permissions? [duplicate]
How do I drop all tables in Windows MySQL, using command prompt? The reason I want to do this is that our user has access to the database drops, but no access to re-creating the database itself, for this reason we must drop the tables manually. Is there a way to drop all the tables at once? Bear in ...
ActiveRecord: size vs count
...l valid.
You'll adapt the function you use depending on your needs.
Basically:
if you already load all entries, say User.all, then you should use length to avoid another db query
if you haven't anything loaded, use count to make a count query on your db
if you don't want to bother with these con...
grant remote access of MySQL database from any IP address
...this article is for you.
ERROR 1130 (HY000): Host ‘1.2.3.4’ is not allowed to connect to this
MySQL server
Change mysql config
Start with editing mysql config file
vim /etc/mysql/my.cnf
Comment out following lines.
#bind-address = 127.0.0.1
#skip-networking
If you do not...
How to remove all debug logging calls before building the release version of an Android app?
According to Google, I must " deactivate any calls to Log methods in the source code " before publishing my Android app to Google Play. Extract from section 3 of the publication checklist :
...
How can I perform a str_replace in JavaScript, replacing text in JavaScript?
...erf, you can have different levels of efficiency for creating a regex, but all of them are significantly slower than a simple string replace. The regex is slower because:
Fixed-string matches don't have backtracking, compilation steps, ranges, character classes, or a host of other features that ...
What is the difference between RegExp’s exec() function and String’s match() function?
...egular expression is meant to be used in a loop, as it will still retrieve all matched subexpressions. So:
var re = /[^\/]+/g;
var match;
while (match = re.exec('/a/b/c/d')) {
// match is now the next match, in array form.
}
// No more matches.
String.match does this for you and discards th...
MySQL Delete all rows from table and reset ID to zero
I need to delete all rows from a table but when I add a new row, I want the primary key ID, which has an auto increment, to start again from 0 respectively from 1.
...
How do I write the 'cd' command in a makefile?
...
It is actually executing the command, changing the directory to some_directory, however, this is performed in a sub-process shell, and affects neither make nor the shell you're working from.
If you're looking to perform more tasks wit...