Initial project import

tools/v/vlib/x/dataframe/dataframe_test.v

@@ -0,0 +1,67 @@
+import math
+import x.dataframe
+
+const prices_csv = 'symbol,price,qty
+AAPL,189.5,2
+MSFT,420.25,3
+AAPL,191.0,5
+'
+
+fn test_from_csv_and_numeric_series() {
+	df := dataframe.from_csv(prices_csv, dataframe.CsvConfig{})!
+	rows, columns := df.shape()
+	assert rows == 3
+	assert columns == 3
+	assert df.columns == ['symbol', 'price', 'qty']
+	assert df.cell(1, 'symbol')! == 'MSFT'
+
+	prices := df.column('price')!
+	assert prices.len() == 3
+	assert math.alike(prices.mean()!, 266.9166666666667)
+	assert math.alike(prices.min()!, 189.5)
+	assert math.alike(prices.max()!, 420.25)
+	assert math.alike(prices.median()!, 191.0)
+
+	summary := df.describe('qty')!
+	assert summary.count == 3
+	assert math.alike(summary.sum, 10.0)
+	assert math.alike(summary.mean, 3.3333333333333335)
+}
+
+fn test_select_filter_sort_and_value_counts() {
+	df := dataframe.from_csv(prices_csv, dataframe.CsvConfig{})!
+	aapl := df.filter(fn (row dataframe.Row) bool {
+		return row.values['symbol'] == 'AAPL'
+	})
+	assert aapl.height() == 2
+
+	selected := aapl.select(['symbol', 'qty'])!
+	assert selected.width() == 2
+	assert selected.cell(1, 'qty')! == '5'
+
+	sorted := df.sort_by_f64('price', .asc)!
+	assert sorted.cell(0, 'symbol')! == 'AAPL'
+	assert sorted.cell(2, 'symbol')! == 'MSFT'
+
+	counts := df.value_counts('symbol')!
+	assert counts['AAPL'] == 2
+	assert counts['MSFT'] == 1
+}
+
+fn test_from_columns_and_csv_without_header() {
+	df := dataframe.from_columns({
+		'b': ['2', '1']
+		'a': ['x', 'y']
+	})!
+	assert df.columns == ['a', 'b']
+	assert df.cell(0, 'a')! == 'x'
+	assert math.alike(df.column('b')!.median()!, 1.5)
+
+	no_header := dataframe.from_csv('AAPL,189.5
+MSFT,420.25
+', dataframe.CsvConfig{
+		has_header: false
+	})!
+	assert no_header.columns == ['column_0', 'column_1']
+	assert no_header.cell(1, 'column_1')! == '420.25'
+}