Data Cleaning

0%
Coding
Theory
Quiz

    Missing Data Handling

    • Count Missing Values Per Column

      Junior

    • Drop Rows With Missing Values

      Junior

    • Fill Missing Values With Zero

      Junior

    • Missing Value Percentage Per Column

      Junior

    • Replace Sentinel Values With NaN

      Junior

    • Boolean Missing-Value Mask

      Junior

    • Fill Missing Values With Column Median

      Mid

    • Group-Wise Median Imputation

      Mid

    • Drop Sparse Columns by Threshold

      Mid

    • Per-Column Missing Value Fill

      Mid

    • Forward Then Backward Fill

      Mid

    • Normalize Sentinel Tokens to NaN

      Mid

    • Add Missing-Value Indicator Column

      Mid

    • Forward-Fill Within Each Sensor Group

      Senior

    • Time-Weighted Interpolation of Gaps

      Senior

    • Group-wise Mode Imputation

      Senior

    Duplicate Detection Removal

    • Remove Exact Duplicate Rows

      Junior

    • Flag Duplicate Rows Boolean Series

      Junior

    • Count Duplicate Rows

      Junior

    • Deduplicate Rows By Email

      Junior

    • Return Only Duplicated Rows

      Junior

    • Keep Latest Row Per User

      Mid

    • Case-Insensitive Email Deduplication

      Mid

    • Flag Duplicate Orders Column

      Mid

    • Drop All Rows With Conflicting IDs

      Mid

    • Keep Max Score Per Student

      Mid

    • Mark Earlier Duplicate Rows With keep='last'

      Mid

    • Count Distinct Rows

      Mid

    • Latest Reading Per Sensor-Day

      Senior

    • Deduplicate DataFrame by Index Label

      Senior

    • Keep Cheapest Offer, Preserve Order

      Senior

    Type Conversion Parsing

    • Coerce Numeric Strings to Floats

      Junior

    • Object Series to Category

      Junior

    • Convert Whole-Number Floats to int64

      Junior

    • Map Yes/No Series to Booleans

      Junior

    • Convert Integer IDs to Strings

      Junior

    • Coerce Strings to Nullable Int64

      Mid

    • Parse US Currency Strings to Floats

      Mid

    • Ordered Categorical T-Shirt Sizes

      Mid

    • Upgrade to Best Nullable Dtypes

      Mid

    • Percent Strings to Fractions

      Mid

    • Strings To Nullable Boolean Series

      Mid

    • Downcast Int Series Signed

      Mid

    • Repair a Mixed-Type Object Column

      Senior

    • Float Codes to Zero-Padded Strings

      Senior

    • Downcast DataFrame To Shrink Memory

      Senior

    • Parse Thousands Strings to Int64

      Senior

    String Text Cleaning

    • Strip Whitespace From a Series

      Junior

    • Lowercase a String Series

      Junior

    • Filter Rows Containing 'error'

      Junior

    • Strip and Title-Case Names

      Junior

    • String Lengths With `str.len()`

      Junior

    • Zero-Pad Code Strings

      Junior

    • Collapse Internal Whitespace

      Mid

    • Strip Punctuation From a Series

      Mid

    • Extract Area Code With str.extract

      Mid

    • Split Full Name Into Columns

      Mid

    • Extract Email Domain With str.extract

      Mid

    • Split Phone Parts With Capture Groups

      Mid

    • Strip Accents via NFKD Normalization

      Senior

    • Text Normalization Pipeline

      Senior

    • Split Measurements With Named Groups

      Senior

    • Extract All Hashtags With `str.extractall`

      Senior

    Datetime Parsing Cleaning

    • Coerce Mixed Strings to Dates

      Junior

    • Parse ISO Date Strings to Datetime

      Junior

    • Parse Day-First Slash Dates

      Junior

    • Extract Calendar Year From Timestamps

      Junior

    • Normalize Timestamps to ISO Date Strings

      Junior

    • Extract Datetime Component Columns

      Mid

    • Whole-Day Duration Between Dates

      Mid

    • Latest Row Per ID

      Mid

    • Normalize Datetimes to Midnight

      Mid

    • Floor Timestamps to the Hour

      Mid

    • Filter Rows by Calendar Year 2021

      Mid

    • Parse Mixed-Format Date Series

      Senior

    • Localize UTC Then Convert to New York

      Senior

    • Parse Two-Digit Year Dates

      Senior

    • Whole-Year Age From Datetimes

      Senior

    Outlier Detection Treatment

    • Tukey IQR Fences

      Junior

    • IQR Outlier Boolean Mask

      Junior

    • Clip Series To Bounds

      Junior

    • Count IQR Outliers With Tukey Fences

      Junior

    • Remove IQR Outliers From a Column

      Mid

    • Winsorize Column at 5th and 95th Percentiles

      Mid

    • Z-Score Outlier Mask (Sample Std)

      Mid

    • Clip Outliers to IQR Fences

      Mid

    • Replace IQR Outliers With Median

      Mid

    • One-Sided Upper Quantile Capping

      Mid

    • Per-Group IQR Outlier Removal

      Senior

    • MAD Modified Z-Score Outlier Mask

      Senior

    • Group-Wise Winsorization

      Senior

    • Per-Group Tukey Outlier Counts

      Senior

    Value Standardization Mapping

    • Normalize Column Labels to snake_case

      Junior

    • Standardize Country Labels With replace

      Junior

    • Recode Status Codes With map

      Junior

    • Ordinal Severity Label Encoding

      Junior

    • Pounds to Kilograms Conversion

      Junior

    • Bin Ages Into Ordered Groups

      Mid

    • Quartile Binning With qcut

      Mid

    • Min-Max Scale a Series

      Mid

    • Z-Score Standardize With Population Std

      Mid

    • Normalize Mixed Encodings to Booleans

      Mid

    • Consolidate Rare Categories to 'Other'

      Mid

    • Recode Colors With Default

      Mid

    • Grade Scores With pd.cut

      Senior

    • Snake_case Column Normalizer

      Senior

    • Consolidate Rare Categories by Proportion

      Senior

    • Column-Wise Z-Score With ddof=0

      Senior

    Structural Reshaping Validation

    • Unpivot Wide Sales to Long

      Junior

    • Promote Named Index to Column

      Junior

    • Explode List Column To Rows

      Junior

    • Age In-Range Boolean Mask

      Junior

    • Validate Status Against Allowed Set

      Junior

    • Reshape Long to Wide With pivot

      Mid

    • Pivot Sales to Wide Region-by-Product

      Mid

    • Explode Comma-Separated Skills to Rows

      Mid

    • Melt Quarterly Revenue to Long Form

      Mid

    • Filter Prices To Valid Range

      Mid

    • Valid Date Order Mask

      Mid

    • Arithmetic Consistency Flag Column

      Mid

    • Wide Scores to Long with stack

      Senior

    • Multi-Rule Row Validation

      Senior

    • Promote First Row to Header

      Senior

    • Per-Column Dtype Schema Check

      Senior

    • Add Combined Validity Flag Column

      Senior