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count the frequency that a value occurs in a dataframe column
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Use groupby and count:
In [37]:
df = pd.DataFrame({'a':list('abssbab')})
df.groupby('a').count()
Out[37]:
a
a
a 2
b 3
s 2
[3 rows x 1 columns]
See the online docs: http://pandas.pydata.org/pandas-docs/stable/groupby.html
Also value_c...
Create two blank lines in Markdown
I am adding Markdown support to my CMS editor.
15 Answers
15
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Change Git repository directory location.
With Git/Github for Windows, if I have a repository with this directory: C:\dir1\dir2 , what do I need to do to move the repo files to C:\dir1 ? I can obviously physically copy and paste the files, but what do I need to do on the Git side?
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MySQL - SELECT WHERE field IN (subquery) - Extremely slow why?
I've got a couple of duplicates in a database that I want to inspect, so what I did to see which are duplicates, I did this:
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What is the advantage of GCC's __builtin_expect in if else statements?
I came across a #define in which they use __builtin_expect .
6 Answers
6
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What's the difference between SoftReference and WeakReference in Java?
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From Understanding Weak References, by Ethan Nicholas:
Weak references
A weak reference, simply put, is a
reference that isn't strong enough to
force an object to remain in memory.
Weak references allow you to leverage
the ...
Why does “pip install” inside Python raise a SyntaxError?
I'm trying to use pip to install a package. I try to run pip install from the Python shell, but I get a SyntaxError . Why do I get this error? How do I use pip to install the package?
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Fix a Git detached head?
I was doing some work in my repository and noticed a file had local changes. I didn't want them anymore so I deleted the file, thinking I can just checkout a fresh copy. I wanted to do the Git equivalent of
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Can I call a constructor from another constructor (do constructor chaining) in C++?
As a C# developer I'm used to running through constructors:
15 Answers
15
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How can I get column names from a table in Oracle?
...query the database to get the column names , not to be confused with data in the table. For example, if I have a table named EVENT_LOG that contains eventID , eventType , eventDesc , and eventTime , then I would want to retrieve those field names from the query and nothing else.
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