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add a string prefix to each value in a string column using Pandas
...lso yields the desired output:
col
0 stra
1 str0
If you are using Python 3.6+, you can also use f-strings:
df['col'] = df['col'].apply(lambda x: f"str{x}")
yielding the same output.
The f-string version is almost as fast as @RomanPekar's solution (python 3.6.4):
df = pd.DataFrame({'col...
What's the recommended approach to resetting migration history using Django South?
... are taking too long, this worked for me.
rm <app-dir>/migrations/*
python manage.py schemamigration <app-name> --initial
python manage.py migrate <app-name> 0001 --fake --delete-ghost-migrations
Don't forget to manually restore any dependencies on other apps by adding lines li...
When should I use @classmethod and when def method(self)?
...atic method of java or C++. ( static method is a general term I guess ;) )
Python also has @staticmethod. and difference between classmethod and staticmethod is whether you can
access to class or static variable using argument or classname itself.
class TestMethod(object):
cls_var = 1
@clas...
differentiate null=True, blank=True in django
...: CharFields can get saved as NULL in the database (translating to None in Python) if you set null=True. The docs even say to avoid setting null=True because it allows two different kinds of "blanky" values. I just tested this behaviour with Django 1.8/MySQL 5.6
– Edward D'Souz...
How to organize large R programs?
...s top-level namespace (the one that ls() shows).
I was trying to simulate Python's system, where every file is a module. That would be better to have, but this seems OK.
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improve this answe...
Inserting a Link to a Webpage in an IPython Notebook
...
In case it is not a markdown cell, that is with what I went:
from IPython.core.display import display, HTML
display(HTML("""<a href="https://google.at">text</a>"""))
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imp...
How can I get the sha1 hash of a string in node.js?
...S is hashing the UTF-8 representation of the string. Other languages (like Python, PHP or PERL...) are hashing the byte string.
We can add binary argument to use the byte string.
const crypto = require("crypto");
function sha1(data) {
return crypto.createHash("sha1").update(data, "binary").dig...
What is a lambda (function)?
... nice way to write closures. With that power you can do things like this.
Python
def adder(x):
return lambda y: x + y
add5 = adder(5)
add5(1)
6
As you can see from the snippet of Python, the function adder takes in an argument x, and returns an anonymous function, or lambda, that takes anoth...
What is the most efficient way to create a dictionary of two pandas Dataframe columns?
...
In Python 3.6 the fastest way is still the WouterOvermeire one. Kikohs' proposal is slower than the other two options.
import timeit
setup = '''
import pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randint(32, 12...
Django - how to create a file and save it to a model's FileField?
...oring to the right spot, not creating duplicate files etc).
Django 1.4.1
Python 2.7.3
#Model
class MonthEnd(models.Model):
report = models.FileField(db_index=True, upload_to='not_used')
import csv
from os.path import join
#build and store the file
def write_csv():
path = join(settings.M...