Replace values ​​in Pandas dataframe with regular expressions

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We already discussed in the previous article, how to replace some known string values ‚Äã‚Äãin a data frame . In this post, we will use regular expressions to replace strings that have some pattern.

Problem # 1: You are presented with a dataframe that contains detailed information about various events in different cities. For those cities that start with the keyword "New" or "New", change it to "New".

Solution: we are going to use a regular expression to detect such names, and then we’ll use Dataframe.replace () to replace those names.

# import pandas as pd

import pandas as pd


# Let’s create the Dataframe

df = pd.DataFrame ({ ’ City’ : [ ’New York’ , ’ Parague’ , ’New Delhi’ , ’Venice’ , ’ new Orleans ’ ],

’ Event’ : [ ’Music’ , ’Poetry’ , ’ Theater’ , ’Comedy’ , ’ Tech_Summit’ ],

’ Cost’ : [ 10000 , 5000 , 15000 , 2000 , 12000 ]})


# Let’s create an index

index_ = [pd.Period ( ’02-2018’ ), pd.Period ( ’ 04-2018’ ),

pd.Period ( ’06-2018’ ), pd.Period ( ’ 10-2018’ ), pd.Period ( ’12-2018’ )]


# Set index

df.index = index_


# Print the data frame < / p>

print (df)

Output:

We will now write a regular expression to match the string, and then we will use Dataframe.replace () to replace those names.

# replace the corresponding lines

df_updated = df.replace (to_replace = ’[nN] ew’ , value = ’New_’ , regex = True )


# Print the updated data frame

print (df_updated)

Output:

As we can see from the output, old lines have been successfully replaced with new ones.

Problem # 2: You are provided with a dataframe that contains detailed information about various events in different cities. Certain city names contain some additional details in parentheses. Look for such names and remove additional details.

Solution: For this task, we will write our own custom function using regular expressions to define and update the names of these cities. In addition, we will use Dataframe.apply () to apply our custom function to each column value.

# import pandas as pd

import pandas as pd


# Let’s create the Dataframe

df = pd.DataFrame ({ ’City’ : [ ’ New York (City) ’ , ’ Parague’ , ’New Delhi (Delhi)’ , ’Venice’ , ’ new Orleans’ ],

’ Event’ : [ ’ Music’ , ’Poetry’ , ’Theater’ , ’Comedy’ , ’ Tech_Summit’ ],

’Cost’ : [ 10000 , 5000 , 15000 , 2000 , 12000 ]})


# Let’s go Let’s not create an index

index_ = [pd .Period ( ’02-2018’ ), pd.Period ( ’04-2018’ ),

pd.Period ( ’06-2018’ ), pd.Period ( ’ 10-2018’ ), pd.Period ( ’12-2018’ )]


# Set index

df.index = index_


# Print the data frame

print (df)

Output:

We will now write our own customized function to match the description in city names.

# Import re-batch to use regular expressions

import re


# Function to clean up names

def Clean_names (City_name):

# Search for open parenthesis in title with followed by

# any characters are repeated any number of times

if re.search ( ’ (. * ’ , City_name):

# Retrieve the position of the beginning of the pattern

pos = re.search ( ’(. * ’ , City_name) .start ()

# return the cleared name

return City_name [: pos]

else :

# if cleanup is required, return same name

return City_name


# Updated city columns

df [ ’City’ ] = df [ ’City ’ ]. apply (Clean_names)


# Print updated data frame

print (df)

Output:

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Replace values ​​in Pandas dataframe with regular expressions __del__: Questions

How can I make a time delay in Python?

5 answers

I would like to know how to put a time delay in a Python script.

2973

Answer #1

import time
time.sleep(5)   # Delays for 5 seconds. You can also use a float value.

Here is another example where something is run approximately once a minute:

import time
while True:
    print("This prints once a minute.")
    time.sleep(60) # Delay for 1 minute (60 seconds).

2973

Answer #2

You can use the sleep() function in the time module. It can take a float argument for sub-second resolution.

from time import sleep
sleep(0.1) # Time in seconds

Replace values ​​in Pandas dataframe with regular expressions __del__: Questions

How to delete a file or folder in Python?

5 answers

How do I delete a file or folder in Python?

2639

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Path objects from the Python 3.4+ pathlib module also expose these instance methods:

cos

How do I install pip on macOS or OS X?

5 answers

I spent most of the day yesterday searching for a clear answer for installing pip (package manager for Python). I can"t find a good solution.

How do I install it?

1672

Answer #1

UPDATE (Jan 2019):

easy_install has been deprecated. Please use get-pip.py instead.


Old answer:

easy_install pip

If you need admin privileges to run this, try:

sudo easy_install pip

1672

Answer #2

⚡️ TL;DR — One line solution.

All you have to do is:

sudo easy_install pip

2019: ⚠️easy_install has been deprecated. Check Method #2 below for preferred installation!

Details:

⚡️ OK, I read the solutions given above, but here"s an EASY solution to install pip.

MacOS comes with Python installed. But to make sure that you have Python installed open the terminal and run the following command.

python --version

If this command returns a version number that means Python exists. Which also means that you already have access to easy_install considering you are using macOS/OSX.

ℹ️ Now, all you have to do is run the following command.

sudo easy_install pip

After that, pip will be installed and you"ll be able to use it for installing other packages.

Let me know if you have any problems installing pip this way.

Cheers!

P.S. I ended up blogging a post about it. QuickTip: How Do I Install pip on macOS or OS X?


✅ UPDATE (Jan 2019): METHOD #2: Two line solution —

easy_install has been deprecated. Please use get-pip.py instead.

First of all download the get-pip file

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py

Now run this file to install pip

python get-pip.py

That should do it.

Another gif you said? Here ya go!

1672

Answer #3

You can install it through Homebrew on OS X. Why would you install Python with Homebrew?

The version of Python that ships with OS X is great for learning but it’s not good for development. The version shipped with OS X may be out of date from the official current Python release, which is considered the stable production version. (source)

Homebrew is something of a package manager for OS X. Find more details on the Homebrew page. Once Homebrew is installed, run the following to install the latest Python, Pip & Setuptools:

brew install python

We hope this article has helped you to resolve the problem. Apart from Replace values ​​in Pandas dataframe with regular expressions, check other __del__-related topics.

Want to excel in Python? See our review of the best Python online courses 2022. If you are interested in Data Science, check also how to learn programming in R.

By the way, this material is also available in other languages:



Oliver Jackson

New York | 2022-12-10

repeat is always a bit confusing 😭 Replace values ​​in Pandas dataframe with regular expressions is not the only problem I encountered. I am just not quite sure it is the best method

Chen Schteiner

Prague | 2022-12-10

I was preparing for my coding interview, thanks for clarifying this - Replace values ​​in Pandas dataframe with regular expressions in Python is not the simplest one. Will get back tomorrow with feedback

Ken Robinson

Abu Dhabi | 2022-12-10

Maybe there are another answers? What Replace values ​​in Pandas dataframe with regular expressions exactly means?. I just hope that will not emerge anymore

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