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To find whether a column exists in data frame or not
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all(c("d", "e", "f") %in% colnames(dat))
– skan
Jul 28 '17 at 19:59
add a comment
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CSS Image size, how to fill, not stretch?
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Since you can resize the image purely in the CSS, this allows you to use a large image and then scale it down according to each device's pixel density by using media queries.
– Marcelo De Polli
Aug 1 '12 at 16:59
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Setup RSpec to test a gem (not Rails)
...my_gem ) to setup the structure for the new gem and edit the *.gemspec manually.
I also added s.add_development_dependency "rspec", ">= 2.0.0" to gemspec and did a bundle install .
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How do you read from stdin?
I'm trying to do some of the code golf challenges, but they all require the input to be taken from stdin . How do I get that in Python?
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How to disable / enable dialog negative positive buttons?
...ertDialog.Builder(MainActivity.this);
builder.setIcon(android.R.drawable.ic_dialog_info);
builder.setTitle("Alert dialog title");
builder.setMessage("This is the example code snippet to disable button if edittext attached to dialog is empty.");
builder.setPositiveButton("PositiveButton",
new...
Do htmlspecialchars and mysql_real_escape_string keep my PHP code safe from injection?
... is effectively just a string escaping function. It is not a magic bullet. All it will do is escape dangerous characters in order that they can be safe to use in a single query string. However, if you do not sanitise your inputs beforehand, then you will be vulnerable to certain attack vectors.
Ima...
Should I use s and s inside my s?
...s point, I'd keep the <ul><li> elements, reason being that not all browsers support HTML5 tags yet.
For example, I ran into an issue using the <header> tag - Chrome and FF worked like a charm, but Opera borked.
Until all browsers support HTML completely, I'd stick them in, but re...
Pandas aggregate count distinct
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How about either of:
>>> df
date duration user_id
0 2013-04-01 30 0001
1 2013-04-01 15 0001
2 2013-04-01 20 0002
3 2013-04-02 15 0002
4 2013-04-02 30 0002
>>> df.groupby("date").agg({"duration": np.sum, "use...
Removing list of vms in vagrant cache
...s untouched, though. Meaning one still has to unregister and delete it manually. The very simple thing should be that vagrant does its job properly when given $ vagrant destroy -f <id>
– silverdr
Dec 14 '15 at 16:04
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Hidden features of HTML
...ge Contains Both Secure and Non-Secure Items" error message in IE, keeping all your asset requests within the same protocol.
Caveat: When used on a <link> or @import for a stylesheet, IE7 and IE8 download the file twice. All other uses, however, are just fine.
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