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Load data from txt with pandas

python
dataframe
pandas
data-manipulation
Nikita BarsukovbyNikita Barsukov·Dec 23, 2024
TLDR

Load text data into a Pandas DataFrame using pd.read_csv(), making sure you correctly specify your file's delimiter.

For comma-separated values (CSV):

import pandas as pd df = pd.read_csv('data.txt') # Comma is default so no delimiter needed

For other delimiters like tabs or semicolons:

df = pd.read_csv('data.txt', delimiter='\t') # for tabs df = pd.read_csv('data.txt', delimiter=';') # for semicolons

The delimiter should match your file's specific format.

Dealing with space-separated files

For space-separated files, make space the separator using " ":

df = pd.read_csv('data.txt', sep=' ') # Space, the final frontier

When there's no headers present, use header=None. This prevents Pandas from considering the first data row as the header:

df = pd.read_csv('data.txt', sep=' ', header=None) # Playing "Hide and Seek" with headers

After the file is loaded, assign column names to enhance the usability of your data:

df.columns = ['Col1', 'Col2', 'Col3'] # Giving your columns the cool names they deserve

When you're dealing with fixed-width formatted files or inconsistent spacing, use pd.read_fwf(). This is Pandas' way of saying, "I've got this, just let me handle it":

df = pd.read_fwf('data.txt') # Pandas, dealing with awkward spaces so you don't have to

Ensuring data is read correctly

It's not just about reading data; it's about reading it right. You may need to deal with complex delimiters or specify column names upfront:

df = pd.read_csv('data.txt', delimiter='[,\t;]+', engine='python') # Multi-delimiter chaos, unleashed df = pd.read_csv('data.txt', sep=' ', names=['ID', 'Val1', 'Val2'], header=None) # Call me by my name

Taking care of potential issues

Incorrect data parse

If your data appears incorrect, check your file path and delimiter. A mere mismatch can bungle up your DataFrame:

import os if os.path.exists('data.txt'): df = pd.read_csv('data.txt', sep='|') # "|" or not "|", that is the question else: print("File not found.") # File playing "Hide and Seek"

Data type mismatch

Pandas automatically infers data types, but can get confused by mixed data types. Specify dtype upfront:

df = pd.read_csv('data.txt', sep=' ', dtype={'ID': int, 'Val1': float}) # Pandas, you classification junkie!

Memory constraints

When processing large files, data size can be an issue. Using chunksize or iterator parameters can come in handy:

chunk_iter = pd.read_csv('data.txt', chunksize=10000) # Pandas diet: small chunks, less memory

Data Manipulation Simplified

Once you've tackled the data import, all you need is ways to access and manipulate your data effectively:

# Accessing data at the second row, third column value = df.iloc[1, 2] # Playing "Hide and Seek" with data elements # Creating a new dataframe based on specific conditions new_df = df[df['Col1'] > some_value] # Your very own slice of data # Transforming data with a lambda function df['Col2'] = df['Col2'].apply(lambda x: x * 2) # Because who doesn't like a little change?