1 files changed, 58 insertions, 1 deletions

diff --git a/libprakpp/include/praktable.hpp b/libprakpp/include/praktable.hpp
index daccedc..2cfa500 100644
--- a/libprakpp/include/praktable.hpp
+++ b/libprakpp/include/praktable.hpp
@@ -111,7 +111,39 @@ public:
 		bool operator==(const iterator& other) {
 			return parent == other.parent && col_index == other.col_index && data_index == other.data_index;
 		}
-		value_type &operator*() { return parent->data[data_index]; };
+		reference operator*() { return parent->data[data_index]; };
+	};
+	struct const_iterator {
+		const table *parent;
+		size_t columns;
+		size_t col_index = 0, data_index = 0;
+		using iterator_category = std::bidirectional_iterator_tag;
+		using value_type = dtype;
+		using difference_type = ptrdiff_t;
+		using pointer = const dtype *;
+		using reference = const dtype &;
+		const_iterator() = default;
+		const_iterator(const const_iterator& other) = default;
+		const_iterator& operator=(const const_iterator& other) = default;
+		const_iterator(const table *new_parent, const std::string &column, size_t row_idx = 0) 
+		 	: parent{new_parent}, columns(new_parent->columns) 
+		{
+			col_index = parent->index(column);
+			data_index = col_index + row_idx * new_parent->columns;
+		}
+		const_iterator &operator++() { data_index += columns; return *this; }
+		const_iterator &operator--() { data_index -= columns; return *this; }
+		const_iterator operator++(int) { const_iterator ret = *this; ++(*this); return ret; }
+		const_iterator operator--(int) { const_iterator ret = *this; --(*this); return ret; }
+		const_iterator &operator+(int x) { data_index += columns * x; return *this; }
+		const_iterator &operator-(int x) { data_index -= columns * x; return *this; }
+		std::strong_ordering operator<=>(const const_iterator& other) const {
+			return parent == other.parent && col_index == other.col_index && data_index <=> other.data_index;
+		}
+		bool operator==(const const_iterator& other) const {
+			return parent == other.parent && col_index == other.col_index && data_index == other.data_index;
+		}
+		reference operator*() const { return parent->data[data_index]; };
 	};
 	// Optional rownames: names of rows
 	std::vector<std::string> opt_rownames;
@@ -177,7 +209,9 @@ public:
 	}
 
 	iterator begin(std::string column) { return iterator(this, column); }
+	const_iterator cbegin(std::string column) const { return const_iterator(this, column); }
 	iterator end(std::string column) { return iterator(this, column, rows); }
+	const_iterator cend(std::string column) const { return const_iterator(this, column, rows); }
 
 	dtype & SUBSCR_OPRTR (const std::string &column, size_t row) noexcept(false) {
 		size_t i = index(column);
@@ -240,6 +274,16 @@ public:
 		return *this;
 	}
 
+	table& apply(function_type function, const std::string& arg, std::optional<std::string> result) {
+		size_t result_index = result.has_value() ? index(*result) : 0;
+		for (size_t i = 0; i < rows; ++i) {
+			const std::vector<dtype> v(1, SUBSCR_OPRTR(arg, i));
+			if (result.has_value()) data[columns * i + result_index] = function(v);
+			else (void)function(v);
+		}
+		return *this;
+	}
+
 	table &apply_n(function_type function, std::vector<iterator> cols, size_t n, std::optional<std::string> result) {
 		size_t result_index = result.has_value() ? index(*result) : 0;
 		for (size_t i = 0; i < n; ++i) {
@@ -475,6 +519,19 @@ public:
 		return accum / rows;
 	}
 
+	dtype col_max(const std::string &column) {
+		dtype max = dtype{};
+		for (auto it = begin(column); it != end(column); ++it) 
+			max = max < *it ? *it : max;
+		return max;
+	}
+	dtype col_min(const std::string &column) {
+		dtype min = dtype{};
+		for (auto it = begin(column); it != end(column); ++it) 
+			min = min > *it ? *it : min;
+		return min;
+	}
+
 	// calculate standard deviation of the column
 	dtype col_stddev(const std::string &column) {
 		dtype accum = dtype{};