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feat(calc): add distinct count, median, std dev, and copy stats summary action (#573) #589

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Merged
ZhuchkaTriplesix merged 1 commit into from
Aug 25, 2026
Merged

feat(calc): add distinct count, median, std dev, and copy stats summary action (#573) #589

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170 changes: 170 additions & 0 deletions lib/features/main_screen/data_grid_calc_bar.dart
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import 'package:flutter/material.dart' as material;
import 'package:flutter/services.dart';
import 'package:querya_desktop/features/main_screen/grid_selection_calc_engine.dart';
import 'package:shadcn_flutter/shadcn_flutter.dart';

/// Status bar footer for Data Grid displaying live selection statistics (Count, Distinct, Sum, Avg, Median, Min, Max).
class DataGridCalcBar extends StatelessWidget {
const DataGridCalcBar({
super.key,
required this.stats,
});

final GridCalcStats stats;

@override
Widget build(BuildContext context) {
if (stats.totalCount <= 1 && !stats.hasNumericStats) {
return const material.SizedBox.shrink();
}

final cs = Theme.of(context).colorScheme;

return material.Container(
height: 26,
padding: const material.EdgeInsets.symmetric(horizontal: 10),
decoration: material.BoxDecoration(
color: cs.card,
border: material.Border(
top: material.BorderSide(
color: cs.border.withValues(alpha: 0.35),
width: 1,
),
),
),
child: material.Row(
children: [
material.Expanded(
child: material.SingleChildScrollView(
scrollDirection: material.Axis.horizontal,
child: material.Row(
mainAxisSize: material.MainAxisSize.min,
children: [
_StatBadge(
label: 'Count',
value: '${stats.totalCount}',
),
const Gap(8),
_StatBadge(
label: 'Distinct',
value: '${stats.distinctCount}',
),
if (stats.nullCount > 0) ...[
const Gap(8),
_StatBadge(
label: 'NULLs',
value: '${stats.nullCount}',
),
],
if (stats.hasNumericStats) ...[
const Gap(8),
_StatBadge(
label: 'Sum',
value: GridSelectionCalcEngine.formatNum(stats.sum),
),
const Gap(8),
_StatBadge(
label: 'Avg',
value: GridSelectionCalcEngine.formatNum(stats.average),
),
if (stats.median != null) ...[
const Gap(8),
_StatBadge(
label: 'Median',
value: GridSelectionCalcEngine.formatNum(stats.median),
),
],
const Gap(8),
_StatBadge(
label: 'Min',
value: GridSelectionCalcEngine.formatNum(stats.min),
),
const Gap(8),
_StatBadge(
label: 'Max',
value: GridSelectionCalcEngine.formatNum(stats.max),
),
],
],
),
),
),
const Gap(6),
material.Tooltip(
message: 'Copy all stats summary',
child: material.InkWell(
onTap: () {
Clipboard.setData(ClipboardData(text: stats.toSummaryString()));
},
borderRadius: material.BorderRadius.circular(3),
child: material.Padding(
padding: const material.EdgeInsets.symmetric(horizontal: 4, vertical: 2),
child: material.Row(
mainAxisSize: material.MainAxisSize.min,
children: [
material.Icon(
material.Icons.copy_all_rounded,
size: 13,
color: cs.mutedForeground,
),
const Gap(3),
Text('Copy Stats', style: TextStyle(fontSize: 10.5, color: cs.mutedForeground)),
],
),
),
),
),
],
),
);
}
}

class _StatBadge extends StatelessWidget {
const _StatBadge({
required this.label,
required this.value,
});

final String label;
final String value;

@override
Widget build(BuildContext context) {
final cs = Theme.of(context).colorScheme;

return material.Tooltip(
message: 'Click to copy $label: $value',
child: material.InkWell(
onTap: () {
Clipboard.setData(ClipboardData(text: value));
},
borderRadius: material.BorderRadius.circular(3),
child: material.Padding(
padding: const material.EdgeInsets.symmetric(horizontal: 4, vertical: 2),
child: material.Row(
mainAxisSize: material.MainAxisSize.min,
children: [
Text(
'$label: ',
style: TextStyle(
fontSize: 11,
color: cs.mutedForeground,
),
),
Text(
value,
style: TextStyle(
fontSize: 11,
fontWeight: FontWeight.w600,
color: cs.foreground,
fontFamily: 'monospace',
),
),
],
),
),
),
);
}
}
181 changes: 181 additions & 0 deletions lib/features/main_screen/grid_selection_calc_engine.dart
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import 'dart:math' as math;
import 'package:flutter/foundation.dart';

/// Aggregated statistical results for a selection of grid cell values.
@immutable
class GridCalcStats {
const GridCalcStats({
required this.totalCount,
required this.distinctCount,
required this.numericCount,
required this.nullCount,
this.sum,
this.average,
this.median,
this.min,
this.max,
this.stdDev,
});

static const empty = GridCalcStats(
totalCount: 0,
distinctCount: 0,
numericCount: 0,
nullCount: 0,
);

final int totalCount;
final int distinctCount;
final int numericCount;
final int nullCount;
final double? sum;
final double? average;
final double? median;
final double? min;
final double? max;
final double? stdDev;

bool get hasNumericStats => numericCount > 0 && sum != null;

/// Formats all available statistics into a single copyable summary string.
String toSummaryString() {
final parts = <String>[
'Count: $totalCount',
'Distinct: $distinctCount',
];
if (nullCount > 0) {
parts.add('NULLs: $nullCount');
}
if (hasNumericStats) {
parts.add('Sum: ${GridSelectionCalcEngine.formatNum(sum)}');
parts.add('Avg: ${GridSelectionCalcEngine.formatNum(average)}');
if (median != null) {
parts.add('Median: ${GridSelectionCalcEngine.formatNum(median)}');
}
parts.add('Min: ${GridSelectionCalcEngine.formatNum(min)}');
parts.add('Max: ${GridSelectionCalcEngine.formatNum(max)}');
if (stdDev != null) {
parts.add('StdDev: ${GridSelectionCalcEngine.formatNum(stdDev)}');
}
}
return parts.join(' | ');
}

@override
bool operator ==(Object other) =>
identical(this, other) ||
other is GridCalcStats &&
totalCount == other.totalCount &&
distinctCount == other.distinctCount &&
numericCount == other.numericCount &&
nullCount == other.nullCount &&
sum == other.sum &&
average == other.average &&
median == other.median &&
min == other.min &&
max == other.max &&
stdDev == other.stdDev;

@override
int get hashCode => Object.hash(
totalCount,
distinctCount,
numericCount,
nullCount,
sum,
average,
median,
min,
max,
stdDev,
);
}

/// Calculation engine for computing stats (Count, Distinct, Sum, Avg, Median, Min, Max, StdDev) on grid selections.
abstract final class GridSelectionCalcEngine {
/// Computes statistics for a list of string cell values.
static GridCalcStats compute(List<String> values) {
if (values.isEmpty) return GridCalcStats.empty;

final total = values.length;
var nulls = 0;
final distinctSet = <String>{};
final numericList = <double>[];
var sum = 0.0;
double? minVal;
double? maxVal;

for (final raw in values) {
final trimmed = raw.trim();
if (trimmed == 'NULL' || trimmed.isEmpty) {
nulls++;
continue;
}

distinctSet.add(trimmed);

// Try parsing numeric values (stripping commas if present)
final normalized = trimmed.replaceAll(',', '');
final parsed = double.tryParse(normalized);
if (parsed != null && !parsed.isNaN && !parsed.isInfinite) {
numericList.add(parsed);
sum += parsed;
if (minVal == null || parsed < minVal) {
minVal = parsed;
}
if (maxVal == null || parsed > maxVal) {
maxVal = parsed;
}
}
}

final numericCount = numericList.length;
final avg = numericCount > 0 ? sum / numericCount : null;

// Calculate median
double? median;
if (numericCount > 0) {
numericList.sort();
final mid = numericCount ~/ 2;
if (numericCount.isOdd) {
median = numericList[mid];
} else {
median = (numericList[mid - 1] + numericList[mid]) / 2.0;
}
}

// Calculate standard deviation
double? stdDev;
if (numericCount > 1 && avg != null) {
var varianceSum = 0.0;
for (final n in numericList) {
varianceSum += math.pow(n - avg, 2);
}
stdDev = math.sqrt(varianceSum / (numericCount - 1));
}

return GridCalcStats(
totalCount: total,
distinctCount: distinctSet.length,
numericCount: numericCount,
nullCount: nulls,
sum: numericCount > 0 ? sum : null,
average: avg,
median: median,
min: minVal,
max: maxVal,
stdDev: stdDev,
);
}

/// Formats a numeric stat cleanly for UI display.
static String formatNum(double? val) {
if (val == null) return '-';
if (val == val.roundToDouble()) {
return val.toInt().toString();
}
// Limit decimal precision to 4 decimal places
final formatted = val.toStringAsFixed(4);
return formatted.replaceAll(RegExp(r'0+$'), '').replaceAll(RegExp(r'\.$'), '');
}
}
11 changes: 11 additions & 0 deletions test/features/main_screen/data_grid_engines_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -165,17 +165,28 @@ void main() {
test('computes correct stats for numeric values', () {
final stats = GridSelectionCalcEngine.compute(['10', '20', '30', '40']);
expect(stats.totalCount, equals(4));
expect(stats.distinctCount, equals(4));
expect(stats.numericCount, equals(4));
expect(stats.nullCount, equals(0));
expect(stats.sum, equals(100.0));
expect(stats.average, equals(25.0));
expect(stats.median, equals(25.0));
expect(stats.min, equals(10.0));
expect(stats.max, equals(40.0));
});

test('computes odd-length median and distinct count with duplicates', () {
final stats = GridSelectionCalcEngine.compute(['10', '20', '20', '50', '100']);
expect(stats.distinctCount, equals(4));
expect(stats.median, equals(20.0));
expect(stats.toSummaryString(), contains('Count: 5 | Distinct: 4'));
expect(stats.toSummaryString(), contains('Median: 20'));
});

test('handles NULLs and mixed string data', () {
final stats = GridSelectionCalcEngine.compute(['10', 'NULL', 'text', '50.5']);
expect(stats.totalCount, equals(4));
expect(stats.distinctCount, equals(3));
expect(stats.numericCount, equals(2));
expect(stats.nullCount, equals(1));
expect(stats.sum, equals(60.5));
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