visibility Static layout preview of Fix Missing Values, shown with a file imported and a completed run (per-column missingness profile + before/after results). All pages →

# Fix Missing Values

Runs 100% locally

Find blank cells (even hidden ones) and fill them in or remove them.

description Using survey_responses.csv from the upload screen.
Preview: survey_responses.csv

2,150 rows, 6 columns

| respondent_id | age | region | income | satisfaction | comments
--- | --- | --- | --- | --- | --- | ---
0 | R-1001 | 34 | West | 52000 | 4 | great service
1 | R-1002 | N/A | East |  | 3 | ?
2 | R-1003 | 41 | - | 61000 | NULL | none
3 | R-1004 | 29 | South | N/A | 5 | quick

## Missingness profile

Rows
2,150
Cells missing
1,043
% cells missing
8.1%
Complete rows
1,388

column | dtype | missing | missing_pct | disguised | has_missing
--- | --- | --- | --- | --- | ---
respondent_id | object | 0 | 0.0% | 0 | False
age | float64 | 187 | 8.7% | 61 | True
region | object | 142 | 6.6% | 142 | True
income | float64 | 329 | 15.3% | 118 | True
satisfaction | float64 | 95 | 4.4% | 40 | True
comments | object | 290 | 13.5% | 290 | True

Options

### Strategy

layers Resolution order: per-column override → global strategy → preset. The most specific setting wins; layers it overrides are dimmed.
Preset
info Overridden by Global strategy → median (set under Advanced options). Presets apply only when global is “(use preset)”.
detect-only (standardize sentinels to NaN, no fill or drop) safe-fill (numeric → median, categorical → mode) drop-incomplete (drop any row with missing)
detect-only: replace 'N/A', '-', 'NULL', etc. with real NaN, then stop. safe-fill: also fill — numeric columns with median, others with mode. drop-incomplete: also drop every row that has any missing cell.
Advanced options

#### Detection

check Standardize disguised nulls to NaN
Blanks in disguise (N/A, dash, NULL) — comma-separated
N/A, n/a, NA, NULL, null, None, -, --, ?, #N/A
Text that really means “empty.” Matched case-insensitively after stripping whitespace.

#### Strategy override

Global strategy
median
drop_row / drop_col use the thresholds below. mean / median / interpolate are numeric only — non-numeric columns fall back to the categorical strategy.
Categorical fallback (for non-numeric columns)
mode

#### Drop thresholds

Row drop threshold (drop rows with ≥ this fraction missing across selected cols)
1.00
Column drop threshold (drop columns with ≥ this fraction missing)
1.00

#### Scope

Columns to handle (default: all)
respondent_id ✕ age ✕ region ✕ income ✕ satisfaction ✕ comments ✕
Columns to skip
Choose columns

#### Per-column strategy overrides (optional)

Set a different strategy for specific columns. Leave any row blank to use the global strategy.

Column | Override | Resolves to
--- | --- | ---
age | (global) | median · global
region | (global) | mode · global → categorical fallback
income | (global) | median · global
satisfaction | (global) | median · global
comments | constant | constant · this column

## Results

Sentinels → NaN
651
Cells filled
1,043
Rows dropped
0
Columns dropped
0

Missingness — before vs. after

column | before_missing | before_pct | after_missing | after_pct | strategy
--- | --- | --- | --- | --- | ---
respondent_id | 0 | 0.0 | 0 | 0.0 | —
age | 187 | 8.7 | 0 | 0.0 | median
region | 142 | 6.6 | 0 | 0.0 | mode
income | 329 | 15.3 | 0 | 0.0 | median
satisfaction | 95 | 4.4 | 0 | 0.0 | median
comments | 290 | 13.5 | 0 | 0.0 | constant

Audit (first 50 changes)

row | column | old_value | new_value | reason
--- | --- | --- | --- | ---
2 | age | N/A | 37.0 | fill: median
2 | income | (blank) | 54000.0 | fill: median
2 | comments | ? | (no comment) | fill: constant
3 | region | - | West | fill: mode
3 | satisfaction | NULL | 4.0 | fill: median
4 | income | N/A | 54000.0 | fill: median

… and 1,037 more (download the full audit below).

Handled preview (first 10 rows)

| respondent_id | age | region | income | satisfaction | comments
--- | --- | --- | --- | --- | --- | ---
0 | R-1001 | 34.0 | West | 52000.0 | 4.0 | great service
1 | R-1002 | 37.0 | East | 54000.0 | 3.0 | (no comment)
2 | R-1003 | 41.0 | West | 61000.0 | 4.0 | none
3 | R-1004 | 29.0 | South | 54000.0 | 5.0 | quick

arrow_forwardMissing values handled. Next, most files need: Find Duplicates →