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How to rename a single column in a data.frame?
...r.name'
This code pretty much does the following:
names(df) looks into all the names in the df
[names(df) == old.var.name] extracts the variable name you want to check
<- 'new.var.name' assigns the new variable name.
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Code for Greatest Common Divisor in Python [closed]
... the result will have the same sign as b", hence gcd(1, -1) == -1 seems totally legit to me.
– Marco Bonelli
Jan 11 '15 at 2:30
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Reintegrate can only be used if revisions X through Y were previously merged from to reintegra
Been using SVN branches with Tortoise 1.6. I've been periodically merging the trunk into the branch to keep it up to date.
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jQuery: checking if the value of a field is null (empty)
...ype]').val().length != 0){}
If you want to check if the element exist at all, you should do that before calling val:
var $d = $('#person_data[document_type]');
if ($d.length != 0) {
if ($d.val().length != 0 ) {...}
}
s...
What are the -Xms and -Xmx parameters when starting JVM?
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The flag Xmx specifies the maximum memory allocation pool for a Java virtual machine (JVM), while Xms specifies the initial memory allocation pool.
This means that your JVM will be started with Xms amount of memory and will be able to use a maximum of Xmx amount of ...
What is the difference between `after_create` and `after_save` and when to use which?
... readers should note that, according to the docs, ActiveRecord's update_all does not invoke any callbacks, including after_*
– user2426679
Jan 10 at 19:34
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receiving error: 'Error: SSL Error: SELF_SIGNED_CERT_IN_CHAIN' while using npm
... on ubuntu - I am receiving the error copied below while attempting to install any new modules via npm (I tested socket.io earlier using http, not https though & am wondering if that could have resulted in the issue with npm/unsigned certs). The error pops up once npm tries to resolve the ' https:/...
Getting the count of unique values in a column in bash
... count the frequency of occurrence of the different values in a column for all the files in a folder and sort them in decreasing order of count (highest count first). How would I accomplish this in a Linux command line environment?
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Gesture recognizer and button actions
...nizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
// Disallow recognition of tap gestures in the segmented control.
if ((touch.view == yourButton)) {//change it to your condition
return NO;
}
return YES;
}
hope it will help
Edit
As Daniel noted you must con...
MySQL - UPDATE query based on SELECT Query
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You can actually do this one of two ways:
MySQL update join syntax:
UPDATE tableA a
INNER JOIN tableB b ON a.name_a = b.name_b
SET validation_check = if(start_dts > end_dts, 'VALID', '')
-- where clause can go here
ANSI SQL syntax...