# Data Science > Data science skill for scientific visualization, statistical analysis, and machine learning with Python. Use when creating plots (matplotlib, seaborn), performing statistical tests (scipy, statsmodels, pingouin), building ML models (scikit-learn), analyzing QWARD metric DataFrames, generating publication-ready figures, conducting hypothesis testing, regression analysis, time series forecasting, or producing APA-formatted statistical reports. Covers pandas, numpy, matplotlib, seaborn, statsmodels, scipy, and scikit-learn workflows. Use when this capability is needed. - Skill: `tomevault-io/data-science-2` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/data-science-2` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/data-science-2/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Data & Analytics - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/data-science-2 --- # Data Science ## Overview Comprehensive data science skill for the QWARD quantum computing project. Covers visualization, statistical analysis, and machine learning workflows for analyzing quantum circuit metrics and producing publication-quality results. ## Quick Start ### Plot QWARD Metrics ```python import matplotlib.pyplot as plt import pandas as pd from qward import Scanner from qward.metrics import QiskitMetrics, ComplexityMetrics scanner = Scanner(circuit=circuit) scanner.add_strategy(QiskitMetrics(circuit)) scanner.add_strategy(ComplexityMetrics(circuit)) results = scanner.calculate_metrics() # Plot complexity metrics df = results['complexity'] fig, ax = plt.subplots(figsize=(10, 6)) df.plot(kind='bar', ax=ax) ax.set_title('Circuit Complexity Metrics') plt.savefig('qward/examples/img/complexity.png', dpi=300, bbox_inches='tight') ``` ### Statistical Comparison ```python from scipy import stats import numpy as np # Compare metrics across circuits t_stat, p_value = stats.ttest_ind(metrics_circuit_a, metrics_circuit_b) cohens_d = (np.mean(metrics_circuit_a) - np.mean(metrics_circuit_b)) / np.sqrt( (np.std(metrics_circuit_a)**2 + np.std(metrics_circuit_b)**2) / 2 ) print(f"t = {t_stat:.2f}, p = {p_value:.3f}, d = {cohens_d:.2f}") ``` ## Core Capabilities ### 1. Visualization (matplotlib + seaborn) For creating plots, charts, and publication-ready figures. **Reference:** See `references/visualization.md` for complete guidance on: - Object-oriented matplotlib API (recommended over pyplot) - All plot types: line, scatter, bar, histogram, heatmap, violin, radar - Multi-panel figures with GridSpec and subplot_mosaic - Seaborn statistical plots with automatic CIs - Colorblind-safe palettes (Okabe-Ito, viridis, cividis) - Publication export (PNG 300dpi, PDF/SVG vector, TIFF) - Journal-specific styling (Nature, Science, Cell dimensions) - 3D plots, contour plots, annotations **Quick patterns:** ```python # Always use OO interface fig, ax = plt.subplots(figsize=(10, 6), constrained_layout=True) ax.plot(x, y, linewidth=2, label='data') ax.set_xlabel('X Label (units)') ax.set_ylabel('Y Label (units)') ax.legend(frameon=False) ax.spines['top'].set_visible(False) ax.spines['right'].set_visible(False) plt.savefig('qward/examples/img/plot.png', dpi=300, bbox_inches='tight') ``` ### 2. Statistical Analysis For hypothesis testing, assumption checking, and reporting. **Reference:** See `references/statistics.md` for complete guidance on: - Test selection guide (parametric vs non-parametric) - Assumption checking (normality, homogeneity, linearity) - t-tests, ANOVA, chi-square, Mann-Whitney, Kruskal-Wallis - Effect sizes (Cohen's d, eta-squared, Cramer's V) with CIs - Power analysis and sample size calculations - Multiple comparison corrections (Bonferroni, FDR) - Bayesian alternatives (Bayes Factors, credible intervals) - APA-style reporting templates ### 3. Statistical Modeling (statsmodels) For regression, GLMs, time series, and econometric analysis. **Reference:** See `references/modeling.md` for complete guidance on: - Linear regression (OLS, WLS, GLS) with diagnostics - Generalized linear models (logistic, Poisson, Gamma) - Time series (ARIMA, SARIMAX, VAR, exponential smoothing) - Formula API (R-style): `smf.ols('y ~ x1 + C(group)', data=df)` - Robust standard errors (HC, HAC, cluster-robust) - Model comparison (AIC, BIC, likelihood ratio tests) - Residual diagnostics and influence analysis ### 4. Machine Learning (scikit-learn) For classification, regression, clustering, and dimensionality reduction. **Reference:** See `references/machine-learning.md` for complete guidance on: - Pipelines and ColumnTransformer for production workflows - Preprocessing (StandardScaler, OneHotEncoder, imputation) - Supervised learning (RandomForest, GradientBoosting, SVM, KNN) - Unsupervised learning (KMeans, DBSCAN, PCA, t-SNE, UMAP) - Cross-validation and hyperparameter tuning (GridSearchCV) - Metrics (classification_report, ROC AUC, silhouette score) - Feature importance and model interpretability ## QWARD-Specific Workflows ### Analyzing Scanner Output ```python from qward import Scanner from qward.metrics import QiskitMetrics, ComplexityMetrics import pandas as pd scanner = Scanner(circuit=circuit) scanner.add_strategy(QiskitMetrics(circuit)) scanner.add_strategy(ComplexityMetrics(circuit)) results = scanner.calculate_metrics() # Each value is a DataFrame for metric_name, df in results.items(): print(f"\n{metric_name}:") print(df.describe()) ``` ### Comparing Circuits ```python import pandas as pd import seaborn as sns import matplotlib.pyplot as plt # Collect metrics across circuits all_metrics = [] for name, circuit in circuits.items(): scanner = Scanner(circuit=circuit) scanner.add_strategy(ComplexityMetrics(circuit)) result = scanner.calculate_metrics() df = result['complexity'] df['circuit'] = name all_metrics.append(df) combined = pd.concat(all_metrics, ignore_index=True) # Visualize fig, ax = plt.subplots(figsize=(10, 6)) sns.boxplot(data=combined, x='circuit', y='gate_density', ax=ax) ax.set_ylabel('Gate Density') sns.despine() plt.savefig('qward/examples/img/comparison.png', dpi=300, bbox_inches='tight') ``` ### Correlation Analysis ```python import seaborn as sns import numpy as np # Correlation between complexity metrics corr = df_metrics.corr(method='spearman') mask = np.triu(np.ones_like(corr, dtype=bool)) fig, ax = plt.subplots(figsize=(8, 6)) sns.heatmap(corr, mask=mask, annot=True, fmt='.2f', cmap='RdBu_r', center=0, square=True, ax=ax) plt.savefig('qward/examples/img/correlation.png', dpi=300, bbox_inches='tight') ``` ## Best Practices ### Visualization - Use OO interface (`fig, ax = plt.subplots()`) for production code - Use `constrained_layout=True` to prevent overlapping - Use colorblind-friendly palettes (viridis, cividis, Okabe-Ito) - Save images to `qward/examples/img/` per project convention - 300 DPI for publications, vector (PDF/SVG) when possible ### Statistics - Always check assumptions before interpreting tests - Report effect sizes with confidence intervals, not just p-values - Use non-parametric tests when normality is violated - Correct for multiple comparisons when testing many hypotheses - Use Bayesian methods when you need evidence for the null ### Machine Learning - Always use Pipelines to prevent data leakage - Use stratified splits for classification - Set `random_state` for reproducibility - Scale features for SVM, KNN, neural networks (not for trees) - Report cross-validated metrics, not just train/test --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/xthecapx) — claim your Tome and manage your conversions.