CSV Data Cleaning and Normalization
The workhorse. Normalizes dates, fixes encodings, splits combined fields, dedupes on any key, standardizes categoricals. Idempotent (safe to re-run) with an auditable transformation report.
Every AI Skill in our directory that reasons about data — SQL queries you can trust, Pandas transformations that don't invent columns, Excel models that reconcile, statistical tests with the right assumptions, and visualizations that make the story clear. Each Skill has been installed, tested against real messy data, and documented for Claude, ChatGPT, Cursor, and Cline.
Data Analysis Skills sit between raw data and business decisions. They accept structured input (CSV files, database rows, Excel workbooks, JSON payloads) and produce answers — a query result, a cleaned dataset, a summary statistic, a chart, a forecast. Under the hood most of these Skills wrap well-known Python libraries (pandas, numpy, scipy, statsmodels, plotly, matplotlib) or delegate to a database engine directly.
The value the Skill layer adds is discipline — refusing to invent columns that aren't in the data, checking dtypes before applying operations that require specific types, flagging when a query result seems surprisingly large or small, and asking clarifying questions when the input is ambiguous ("which date column did you mean?"). Plain LLM output for data work is notoriously prone to hallucinated columns and quietly incorrect aggregations; Skills lock the discipline in.
What lives here vs. elsewhere: if the Skill's output is a data artifact (a query, a cleaned frame, a chart, a summary stat), it belongs here. If it produces a document that contains data (a PDF report with charts), that lives in Document Creation. If it fetches data from a live web source, that lives in Web & API. If it's an autonomous multi-step research workflow, see Research & Analysis.
Our editorial picks — heaviest tested, highest reader ratings.
The workhorse. Normalizes dates, fixes encodings, splits combined fields, dedupes on any key, standardizes categoricals. Idempotent (safe to re-run) with an auditable transformation report.
Describe the calculation in plain English; get a working Excel formula. Covers VLOOKUP, XLOOKUP, INDEX/MATCH, SUMIFS, LAMBDA, and dynamic arrays. Verified with sample data.
Ask a question in plain English about a schema; get correct, dialect-aware SQL back. Understands joins, window functions, CTEs. Explains query plans before you run against production.
Filter by sub-type, search by name, sort by recency or alphabetical.
Translate natural language to dialect-aware SQL. Handles joins, window functions, CTEs, subqueries. Explains query plan before execution.
Given a SQL query, explain what it does in plain English and analyze the execution plan for performance issues.
Rewrite MySQL SQL to Postgres-compatible SQL. Handles dialect differences: quoting, functions, DDL, JSON operators.
Analyze slow queries + existing indexes, recommend new indexes. Explains trade-offs (write cost vs read speed).
Scan SQL files for common anti-patterns: implicit cross-joins, missing WHERE, N+1 patterns, unsafe LIMIT ordering.
Apply natural-language transformations to a DataFrame: filters, groupbys, joins, pivots. Refuses to invent columns.
Convert Pandas operations to equivalent SQL for pushing computation down to the database rather than in-memory.
Analyze a DataFrame's memory usage and suggest dtype changes, categorical conversions, or chunked processing.
Resample time-series data (upsampling with interpolation, downsampling with aggregation). Timezone-aware.
Describe the calculation, get a working Excel formula. VLOOKUP, XLOOKUP, INDEX/MATCH, SUMIFS, LAMBDA, dynamic arrays.
Describe the pivot you want; get the pivot table specification applied to your workbook.
Generate charts from data ranges with proper axis labels, legends, title. Recommends chart type from data shape.
Build 3-statement financial models, DCF, unit economics from a spec. Follows standard modeling conventions.
Given data and a hypothesis, select the appropriate statistical test (t-test, ANOVA, chi-square, Mann-Whitney). Checks assumptions first.
Fit linear or logistic regression, produce coefficient table with confidence intervals, run diagnostic checks (residuals, collinearity, leverage).
Fit ARIMA, Prophet, or exponential smoothing to time series. Returns forecast + confidence bands + accuracy metrics.
Produce Plotly or matplotlib charts. Refuses to truncate y-axes to exaggerate differences; annotates the actual data range clearly.
Generate JSON specs for Grafana, Superset, or Looker Studio from natural-language requirements.
Given a chart image, critique for accuracy, clarity, and honesty. Suggests specific improvements.
Normalize dates, fix encodings, split combined fields, dedupe, standardize categoricals. Idempotent with auditable report.
Detect near-duplicate records using edit distance + phonetic matching. Presents candidates for human review before merging.
Flag likely outliers (statistical, contextual, or rule-based) without automatically removing them. You decide what to do.
MCP servers our team pairs with Data Analysis Skills for full workflows.
Query Postgres databases in natural language. Pairs with the SQL Skills for read-only exploration workflows.
Sister database server for MySQL / MariaDB / Aurora MySQL. Same tool surface as Postgres MCP.
Local file-based database. Great for prototyping data models before productionizing.
Data warehouse counterpart for heavier analytics workloads.
Read from and write to Google Sheets. Pairs with Excel-adjacent Skills for cloud-first teams.
Read raw data files from S3 for cleaning and analysis without downloading locally.
Longer-form tutorials for the concepts behind these Skills.
How to structure your data cleaning workflow so AI Skills are additive rather than error-prone.
Rule of thumb: if you have SQL, push down. If you don't, Pandas.
Techniques and Skill patterns to keep AI query generation grounded in the actual schema.
Head-to-head reviews that touch on Data Analysis workflows.
Head-to-head on 100 real query scenarios. Verdict: Claude ahead on complex CTEs, GPT-5 ahead on window functions.
Which DataFrame library is friendlier for AI generation? Trade-offs across dialect familiarity, speed, memory.
When your Data Analysis Skill needs external context, which search backend gets the best cited data?
Our sister sites cover errors and code recipes across the AI ecosystem. Bookmark them for when a Skill hits an edge case.
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