ETL Pipeline for Construction Data

Overview

Based on DDC methodology (Chapter 4.2), this skill enables building automated data pipelines that extract information from various sources, transform it into useful formats, and load it into target systems or generate reports.

Book Reference: "ETL и автоматизация процессов" / "ETL and Process Automation"

"ETL: переход от ручного управления к автоматизации позволяет компаниям обрабатывать данные без постоянного человеческого вмешательства." — DDC Book, Chapter 4.2

ETL Components

┌─────────┐    ┌───────────┐    ┌────────┐
│ EXTRACT │ -> │ TRANSFORM │ -> │  LOAD  │
└─────────┘    └───────────┘    └────────┘
   │               │               │
   ▼               ▼               ▼
 Sources        Process         Outputs
 - PDF          - Clean         - Excel
 - Excel        - Validate      - PDF
 - CSV          - Calculate     - Database
 - BIM          - Merge         - API
 - API          - Aggregate     - Dashboard

Quick Start

import pandas as pd

# Simple ETL Pipeline
def simple_etl_pipeline(input_file, output_file):
    # EXTRACT
    df = pd.read_excel(input_file)

    # TRANSFORM
    df = df.dropna()  # Clean
    df['Total'] = df['Quantity'] * df['Unit_Price']  # Calculate
    summary = df.groupby('Category')['Total'].sum()  # Aggregate

    # LOAD
    summary.to_excel(output_file)
    return summary

# Run
result = simple_etl_pipeline("raw_data.xlsx", "processed_report.xlsx")

Extract: Data Sources

From Multiple Excel Files

import pandas as pd
from pathlib import Path

def extract_excel_files(folder_path, pattern="*.xlsx"):
    """Extract data from multiple Excel files"""
    files = Path(folder_path).glob(pattern)
    all_data = []

    for file in files:
        try:
            df = pd.read_excel(file)
            df['_source_file'] = file.name
            all_data.append(df)
            print(f"Extracted: {file.name}")
        except Exception as e:
            print(f"Error reading {file.name}: {e}")

    if all_data:
        return pd.concat(all_data, ignore_index=True)
    return pd.DataFrame()

# Usage
df = extract_excel_files("./project_data/")

From PDF Documents

import pdfplumber
import pandas as pd

def extract_from_pdfs(pdf_folder):
    """Extract tables from all PDFs in folder"""
    files = Path(pdf_folder).glob("*.pdf")
    all_tables = []

    for pdf_path in files:
        with pdfplumber.open(pdf_path) as pdf:
            for page in pdf.pages:
                tables = page.extract_tables()
                for table in tables:
                    if table and len(table) > 1:
                        df = pd.DataFrame(table[1:], columns=table[0])
                        df['_source'] = pdf_path.name
                        all_tables.append(df)

    return pd.concat(all_tables, ignore_index=True) if all_tables else pd.DataFrame()

From API

import requests
import pandas as pd

def extract_from_api(api_url, headers=None):
    """Extract data from REST API"""
    response = requests.get(api_url, headers=headers)

    if response.status_code == 200:
        data = response.json()
        return pd.DataFrame(data)
    else:
        raise Exception(f"API error: {response.status_code}")

# Usage
df = extract_from_api("https://api.example.com/projects")

From Database

import pandas as pd
import sqlite3

def extract_from_database(db_path, query):
    """Extract data using SQL query"""
    conn = sqlite3.connect(db_path)
    df = pd.read_sql_query(query, conn)
    conn.close()
    return df

# Usage
df = extract_from_database(
    "construction.db",
    "SELECT * FROM elements WHERE category = 'Wall'"
)

Transform: Data Processing

Data Cleaning

def clean_construction_data(df):
    """Standard cleaning for construction data"""
    # Remove empty rows
    df = df.dropna(how='all')

    # Strip whitespace
    for col in df.select_dtypes(include=['object']).columns:
        df[col] = df[col].str.strip()

    # Standardize category names
    if 'Category' in df.columns:
        df['Category'] = df['Category'].str.title()

    # Convert numeric columns
    numeric_cols = ['Volume', 'Area', 'Length', 'Quantity', 'Cost']
    for col in numeric_cols:
        if col in df.columns:
            df[col] = pd.to_numeric(df[col], errors='coerce')

    # Remove duplicates
    df = df.drop_duplicates()

    return df

Data Validation

def validate_construction_data(df, rules):
    """
    Validate data against rules

    Args:
        rules: list of dicts like
        [{'column': 'Volume', 'rule': 'positive'},
         {'column': 'Category', 'rule': 'not_null'}]
    """
    errors = []

    for rule in rules:
        col = rule['column']
        rule_type = rule['rule']

        if col not in df.columns:
            errors.append(f"Missing column: {col}")
            continue

        if rule_type == 'positive':
            invalid = df[df[col] <= 0]
            if len(invalid) > 0:
                errors.append(f"{len(invalid)} rows with non-positive {col}")

        elif rule_type == 'not_null':
            null_count = df[col].isna().sum()
            if null_count > 0:
                errors.append(f"{null_count} null values in {col}")

        elif rule_type == 'unique':
            duplicates = df[col].duplicated().sum()
            if duplicates > 0:
                errors.append(f"{duplicates} duplicate values in {col}")

    return errors

# Usage
validation_rules = [
    {'column': 'Volume', 'rule': 'positive'},
    {'column': 'Category', 'rule': 'not_null'},
    {'column': 'ElementId', 'rule': 'unique'}
]
errors = validate_construction_data(df, validation_rules)

Data Aggregation

def aggregate_by_hierarchy(df, hierarchy=['Project', 'Building', 'Level', 'Category']):
    """Aggregate data at different hierarchy levels"""
    results = {}

    for i in range(1, len(hierarchy) + 1):
        level_cols = hierarchy[:i]
        if all(col in df.columns for col in level_cols):
            agg = df.groupby(level_cols).agg({
                'Volume': 'sum',
                'Cost': 'sum',
                'ElementId': 'count'
            }).rename(columns={'ElementId': 'Count'})

            level_name = '_'.join(level_cols)
            results[level_name] = agg

    return results

# Usage
aggregations = aggregate_by_hierarchy(df)
for name, data in aggregations.items():
    print(f"\n{name}:")
    print(data.head())

Data Enrichment

def enrich_with_prices(df, prices_df):
    """Enrich element data with pricing information"""
    # Merge with price database
    enriched = df.merge(prices_df, on='Category', how='left')

    # Calculate costs
    enriched['Material_Cost'] = enriched['Volume'] * enriched['Unit_Price']
    enriched['Labor_Cost'] = enriched['Volume'] * enriched['Labor_Rate']
    enriched['Total_Cost'] = enriched['Material_Cost'] + enriched['Labor_Cost']

    return enriched

Load: Output Generation

Generate Excel Report

def generate_excel_report(df, summary, output_path):
    """Generate formatted Excel report"""
    with pd.ExcelWriter(output_path, engine='openpyxl') as writer:
        # Raw data
        df.to_excel(writer, sheet_name='Data', index=False)

        # Summary by category
        summary.to_excel(writer, sheet_name='Summary')

        # Pivot table
        if 'Level' in df.columns and 'Category' in df.columns:
            pivot = pd.pivot_table(
                df, values='Volume',
                index='Level', columns='Category',
                aggfunc='sum', fill_value=0
            )
            pivot.to_excel(writer, sheet_name='By_Level')

    print(f"Report saved: {output_path}")

# Usage
generate_excel_report(df, summary, "project_report.xlsx")

Generate PDF Report

from reportlab.lib import colors
from reportlab.lib.pagesizes import letter, A4
from reportlab.platypus import SimpleDocTemplate, Table, TableStyle, Paragraph
from reportlab.lib.styles import getSampleStyleSheet

def generate_pdf_report(df, output_path, title="Construction Report"):
    """Generate PDF report from DataFrame"""
    doc = SimpleDocTemplate(output_path, pagesize=A4)
    elements = []
    styles = getSampleStyleSheet()

    # Title
    elements.append(Paragraph(title, styles['Title']))

    # Convert DataFrame to table
    data = [df.columns.tolist()] + df.values.tolist()
    table = Table(data)

    # Style the table
    table.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), colors.grey),
        ('TEXTCOLOR', (0, 0), (-1, 0), colors.whitesmoke),
        ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
        ('FONTNAME', (0, 0), (-1, 0), 'Helvetica-Bold'),
        ('FONTSIZE', (0, 0), (-1, 0), 10),
        ('BOTTOMPADDING', (0, 0), (-1, 0), 12),
        ('BACKGROUND', (0, 1), (-1, -1), colors.beige),
        ('GRID', (0, 0), (-1, -1), 1, colors.black)
    ]))

    elements.append(table)
    doc.build(elements)
    print(f"PDF saved: {output_path}")

# Usage
generate_pdf_report(summary, "report.pdf")

Load to Database

import sqlite3

def load_to_database(df, db_path, table_name, if_exists='replace'):
    """Load DataFrame to SQLite database"""
    conn = sqlite3.connect(db_path)
    df.to_sql(table_name, conn, if_exists=if_exists, index=False)
    conn.close()
    print(f"Loaded {len(df)} rows to {table_name}")

# Usage
load_to_database(df, "construction.db", "elements")

Complete ETL Pipeline

class ConstructionETLPipeline:
    """Complete ETL pipeline for construction data"""

    def __init__(self, config):
        self.config = config
        self.data = None
        self.errors = []

    def extract(self):
        """Extract data from configured sources"""
        print("Extracting data...")
        sources = []

        # Excel files
        if 'excel_folder' in self.config:
            df = extract_excel_files(self.config['excel_folder'])
            sources.append(df)

        # PDF files
        if 'pdf_folder' in self.config:
            df = extract_from_pdfs(self.config['pdf_folder'])
            sources.append(df)

        self.data = pd.concat(sources, ignore_index=True)
        print(f"Extracted {len(self.data)} records")
        return self

    def transform(self):
        """Apply transformations"""
        print("Transforming data...")

        # Clean
        self.data = clean_construction_data(self.data)

        # Validate
        if 'validation_rules' in self.config:
            self.errors = validate_construction_data(
                self.data, self.config['validation_rules']
            )

        # Enrich with prices if available
        if 'prices_file' in self.config:
            prices = pd.read_excel(self.config['prices_file'])
            self.data = enrich_with_prices(self.data, prices)

        print(f"Transformed {len(self.data)} records")
        return self

    def load(self):
        """Load to configured outputs"""
        print("Loading data...")

        # Excel report
        if 'excel_output' in self.config:
            summary = self.data.groupby('Category').agg({
                'Volume': 'sum', 'Cost': 'sum'
            })
            generate_excel_report(
                self.data, summary, self.config['excel_output']
            )

        # Database
        if 'database' in self.config:
            load_to_database(
                self.data,
                self.config['database'],
                self.config.get('table_name', 'elements')
            )

        print("Pipeline complete!")
        return self

    def run(self):
        """Run complete pipeline"""
        return self.extract().transform().load()

# Usage
config = {
    'excel_folder': './input_data/',
    'prices_file': './prices.xlsx',
    'validation_rules': [
        {'column': 'Volume', 'rule': 'positive'},
        {'column': 'Category', 'rule': 'not_null'}
    ],
    'excel_output': './output/report.xlsx',
    'database': './output/project.db',
    'table_name': 'elements'
}

pipeline = ConstructionETLPipeline(config)
pipeline.run()

Scheduling with Airflow

# airflow_dag.py
from airflow import DAG
from airflow.operators.python import PythonOperator
from datetime import datetime, timedelta

default_args = {
    'owner': 'construction_team',
    'depends_on_past': False,
    'start_date': datetime(2024, 1, 1),
    'retries': 1,
    'retry_delay': timedelta(minutes=5),
}

dag = DAG(
    'construction_etl',
    default_args=default_args,
    description='Daily construction data ETL',
    schedule_interval='@daily',
)

def extract_task():
    # Extract logic
    pass

def transform_task():
    # Transform logic
    pass

def load_task():
    # Load logic
    pass

t1 = PythonOperator(task_id='extract', python_callable=extract_task, dag=dag)
t2 = PythonOperator(task_id='transform', python_callable=transform_task, dag=dag)
t3 = PythonOperator(task_id='load', python_callable=load_task, dag=dag)

t1 >> t2 >> t3

Quick Reference

Stage	Task	Tool/Method
Extract	Read Excel	pd.read_excel()
Extract	Read CSV	pd.read_csv()
Extract	Read PDF	pdfplumber
Extract	Read API	requests.get()
Transform	Clean	df.dropna(), df.str.strip()
Transform	Validate	Custom validation functions
Transform	Calculate	df['new'] = df['a'] * df['b']
Transform	Aggregate	df.groupby().agg()
Load	Excel	df.to_excel()
Load	PDF	reportlab
Load	Database	df.to_sql()
Load	API	requests.post()

Resources

• Book: "Data-Driven Construction" by Artem Boiko, Chapter 4.2
• Website: https://datadrivenconstruction.io
• Airflow: https://airflow.apache.org
• n8n: https://n8n.io

Next Steps

• See bim-validation-pipeline for BIM data validation
• See pdf-report-generator for advanced PDF generation
• See workflow-automation for n8n integration