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Count number of rows within each group
I have a dataframe and I would like to count the number of rows within each group. I reguarly use the aggregate function to sum data as follows:
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Replace all 0 values to NA
...ays in ?'NULL',
NULL represents the null object in R
which is unique and, I guess, can be seen as the most uninformative and empty object.1 Then it becomes not so surprising that
data.frame(x = c(1, NULL, 2))
# x
# 1 1
# 2 2
That is, R does not reserve any space for this null object.2 Mea...
Rounded table corners CSS only
I have searched and searched, but haven't been able to find a solution for my requirement.
17 Answers
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How to hide command output in Bash
...gant for the end user. How do I hide the output when Bash is executing commands?
7 Answers
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How to configure Sublime Text 2/3 to use direct Ctrl+Tab order and to create new tabs after the last
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To achieve the Ctrl+Tab and Ctrl+Shift+Tab behavior you can add the following lines to your sublime-keymap:
{ "keys": ["ctrl+tab"], "command": "next_view" },
{ "keys": ["ctrl+shift+tab"], "command": "prev_view" }
To open sublime-keymap:
click "...
Making 'git log' ignore changes for certain paths
...now (git 1.9/2.0, Q1 2014) with the introduction pathspec magic :(exclude) and its short form :! in commit ef79b1f and commit 1649612, by
Nguyễn Thái Ngọc Duy (pclouds), documentation can be found here.
You now can log everything except a sub-folder content:
git log -- . ":(exclude)sub"
git lo...
How does git compute file hashes?
... | shasum
8ab686eafeb1f44702738c8b0f24f2567c36da6d
Source: http://alblue.bandlem.com/2011/08/git-tip-of-week-objects.html
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How to append something to an array?
...to the length property. The interpreter does an amazing job at that itself and it will not make any difference in The Real World whether you optimize it away or not. If your array becomes so huge that optimizing .length would actually help, most probably an array is not the right data structure anym...
Why is Java's Iterator not an Iterable?
... one may obtain an iterator from an object to traverse over its elements - and there's no need to iterate over a single instance, which is what an iterator represents.
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jsonify a SQLAlchemy result set in Flask [duplicate]
...y.
"""
return [ item.serialize for item in self.many2many]
And now for views I can just do:
return jsonify(json_list=[i.serialize for i in qryresult.all()])
Hope this helps ;)
[Edit 2019]:
In case you have more complex objects or circular references, use a library like marshmallo...