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Read_csv

As explained in Build Python Web Apps with Streamlit

read_csv is a pandas function that reads delimited text data, commonly CSV files, into a dataframe.

read_csv is a pandas function that loads delimited text, commonly a CSV file, into a DataFrame. The simplest call supplies only the file path because useful defaults handle headers, column names, and types. section 6.2.1

Load and inspect sales data

import pandas as pd df = pd.read_csv('sales_data.csv') print(type(df)) df.info() The result is a pandas DataFrame whose rows and columns can be analyzed. Inspection reveals row counts, column names, missing values, and pandas dtypes such as object and float64. section 6.2.1

File location matters when an application runs from a different working directory. Build the CSV path from the Python file’s directory with pathlib instead of hardcoding a machine-specific absolute path. section 6.2.2

Listing 6.1 Loading data using data_loader.py
import pandas as pd
from pathlib import Path

BASE_DIR = Path(__file__).resolve().parent
SALES_DATA_PATH = BASE_DIR / "sales_data.csv"

def load_data():
  return pd.read_csv(SALES_DATA_PATH)

Use this loader pattern to keep path construction separate from application code and return the DataFrame through a reusable load_data function. section 6.2.2

Useful decisions after loading include:

  • Inspect the result with type and info before building dashboard features. section 6.2.1
  • Choose a dtype_backend such as pyarrow when the intended pandas representation differs from object and float64. section 6.2.1
  • Use DataFrame column selection after loading when the application needs only a subset of fields. section 6.2.1

How Build Python Web Apps with Streamlit covers it

How deep it goes
Explains default parsing, DataFrame inspection, dtypes, Arrow backends, column selection, and portable paths without detailing every parameter.
Examples
Uses sales_data.csv, type and info inspection, dtype_backend='pyarrow', selected columns, and a reusable data_loader.py function.
What it assumes
Assumes basic Python imports and files while teaching pandas DataFrames, pandas dtypes, and pathlib-based path construction.
What you can do after
Apply pandas read_csv to load CSV data, inspect its DataFrame structure, and construct deployment-friendly file paths.
How it connects
Connects read_csv with pandas DataFrames, pathlib, Streamlit, DataFrame column selection, and Apache Arrow.

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This explainer was generated by Manning's knowledge graph from the text of Build Python Web Apps with Streamlit. The section links point to the parts of the book it draws on.