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Dynamically select data frame columns using $ and a character value
...3 = sample(5,10,repl=T) )
# We want to sort by 'col3' then by 'col1'
sort_list <- c("col3","col1")
# Use 'do.call' to call order. Seccond argument in do.call is a list of arguments
# to pass to the first argument, in this case 'order'.
# Since a data.frame is really a list, we just subset ...
WebSockets protocol vs HTTP
...kets is better for situations that involve low-latency communication especially for low latency for client to server messages. For server to client data you can get fairly low latency using long-held connections and chunked transfer. However, this doesn't help with client to server latency which req...
How do you set a default value for a MySQL Datetime column?
... need to ALWAYS specify a value for this column or the value will automatically reset itself to "now()" on update. This means that if you do not want the value to change, your UPDATE statement must contain "[your column name] = [your column name]" (or some other value) or the value will become "now(...
Using pickle.dump - TypeError: must be str, not bytes
..., that's why you are here.
import pickle
class MyUser(object):
def __init__(self,name):
self.name = name
user = MyUser('Peter')
print("Before serialization: ")
print(user.name)
print("------------")
serialized = pickle.dumps(user)
filename = 'serialized.native'
with open(filename,...
How can I extract a good quality JPEG image from a video file with ffmpeg?
...ical file sizes and (to my naked eye) appear the same as without qscale at all.
– felwithe
Jan 28 '15 at 23:03
Can you...
How to capture UIView to UIImage without loss of quality on retina display
...IGraphicsBeginImageContext uses a fixed scale factor of 1.0, so you're actually getting exactly the same image on an iPhone 4 as on the other iPhones. I'll bet either the iPhone 4 is applying a filter when you implicitly scale it up or just your brain is picking up on it being less sharp than everyt...
Why should the copy constructor accept its parameter by reference in C++?
... reference, it's by value. To do that you make a copy, and to do that you call the copy constructor. But to do that, we need to make a new value, so we call the copy constructor, and so on...
(You would have infinite recursion because "to make a copy, you need to make a copy".)
...
How do I associate a Vagrant project directory with an existing VirtualBox VM?
...othername".
Stop the machine from provisioning:
Create a file named action_provision in the same dir as the id file, set it's contents to: 1.5:{id} replacing {id} with the id found in step 1.
Setup a new public/private key:
Vagrant uses a private key stored in .vagrant/machines/default/virtualbox/...
submitting a GET form with query string params and hidden params disappear
...the question mark and the parameters, and then cross one's fingers to hope all browsers would leave that URL as it (and validate that the server understands it too). But I'd never rely on that.
By the way: it's not different for non-hidden form fields. For POST the action URL could hold a query stri...
Is it possible to preview stash contents in git?
...shows the last tone, 1 the second last one.. etc. git stash list will show all the available.
– brita_
Jul 18 '14 at 21:13
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