data-transform

Data Transformation (Universal)

Overview

This skill enables you to perform comprehensive data transformations including cleaning, normalization, reshaping, filtering, and feature engineering. Unlike cloud-hosted solutions, this skill uses standard Python data manipulation libraries (pandas, numpy, sklearn) and executes locally in your environment, making it compatible with ALL LLM providers including GPT, Gemini, Claude, DeepSeek, and Qwen.

When to Use This Skill

• Clean and preprocess raw data
• Normalize or scale numeric features
• Reshape data between wide and long formats
• Handle missing values
• Filter and subset datasets
• Merge multiple datasets
• Create new features from existing ones
• Convert data types and formats

How to Use

Step 1: Import Required Libraries

import pandas as pd
import numpy as np
from sklearn.preprocessing import StandardScaler, MinMaxScaler, RobustScaler
from sklearn.preprocessing import LabelEncoder, OneHotEncoder
import warnings
warnings.filterwarnings('ignore')

Step 2: Data Cleaning

# Load data
df = pd.read_csv('data.csv')

# Check for missing values
print("Missing values per column:")
print(df.isnull().sum())

# Remove duplicates
df_clean = df.drop_duplicates()
print(f"Removed {len(df) - len(df_clean)} duplicate rows")

# Remove rows with any missing values
df_clean = df_clean.dropna()

# Or fill missing values
df_clean = df.copy()
df_clean['numeric_col'] = df_clean['numeric_col'].fillna(df_clean['numeric_col'].median())
df_clean['categorical_col'] = df_clean['categorical_col'].fillna('Unknown')

# Remove outliers using IQR method
def remove_outliers(df, column, multiplier=1.5):
    Q1 = df[column].quantile(0.25)
    Q3 = df[column].quantile(0.75)
    IQR = Q3 - Q1
    lower_bound = Q1 - multiplier * IQR
    upper_bound = Q3 + multiplier * IQR
    return df[(df[column] >= lower_bound) & (df[column] <= upper_bound)]

df_clean = remove_outliers(df_clean, 'expression_level')
print(f"✅ Data cleaned: {len(df_clean)} rows remaining")