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cartesian product in pandas
... you can produce a cartesian product using merge (like you would in SQL).
from pandas import DataFrame, merge
df1 = DataFrame({'key':[1,1], 'col1':[1,2],'col2':[3,4]})
df2 = DataFrame({'key':[1,1], 'col3':[5,6]})
merge(df1, df2,on='key')[['col1', 'col2', 'col3']]
Output:
col1 col2 col3
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Remove a character from the end of a variable
...etion appends a / at the end of a directory name. How I can strip this off from a positional parameter?
4 Answers
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Python loop that also accesses previous and next values
...lement, and end iterating at the last-but-one element. So index should run from 1 ... (l-1), not 0 ... l as you have here, and no need for the special-cased if-clauses. Btw, there is a parameter enumerate(..., start=1) but not for end. So we don't realy want to use enumerate().
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java.net.ConnectException: localhost/127.0.0.1:8080 - Connection refused
I am using xampp apache server to serve resources to the application from my machine. But i am getting the above error.
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How can I lock a file using java (if possible)
... opens a file using a FileReader. How can I prevent another (Java) process from opening this file, or at least notify that second process that the file is already opened? Does this automatically make the second process get an exception if the file is open (which solves my problem) or do I have to ex...
What is the difference between an expression and a statement in Python?
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Expression -- from the New Oxford American Dictionary:
expression: Mathematics a collection
of symbols that jointly express a
quantity : the expression for the
circumference of a circle is 2πr.
In gross general terms: Express...
Reusing output from last command in Bash
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You can save yourself from typing $(your_cmd) by using backticks: `your_cmd` According to the Gnu Bash manual they are functionally identical. Of course this is also subject to the warning raised by @memecs
– user2065875
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How to install a private NPM module without my own registry?
...nt to upload to the central registry. The question is, how do I install it from other projects?
14 Answers
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What's the difference between django OneToOneField and ForeignKey?
...s OneToOneField(Engine)
Car2 model uses ForeignKey(Engine2, unique=True)
From within python manage.py shell execute the following:
OneToOneField Example
>>> from testapp.models import Car, Engine
>>> c = Car.objects.get(name='Audi')
>>> e = Engine.objects.get(name='Die...
What does set -e mean in a bash script?
...is preinst file that the script executes before that package is unpacked from its Debian archive (.deb) file.
7 Answers
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