Add docs to StringFrame.

data/string_frame.go

@@ -1,21 +1,26 @@
 package data
 
+// Used for storing matrix-like strings. For example, if you have multiple labels associated with each instance, then you probably need a matrix-like struct to store whole your labels.
 type StringFrame struct {
 	labels [][]string
 }
 
+// Add a row of string to StringFrame
 func (self *StringFrame) Add(row []string) {
 	self.labels = append(self.labels, row)
 }
 
+// Get the string at (i, j)
 func (self *StringFrame) At(i, j int) string {
 	return self.labels[i][j]
 }
 
+// Get the i-th row of string
 func (self *StringFrame) Row(i int) []string {
 	return self.labels[i]
 }
 
+// Get the j-th column of string
 func (self *StringFrame) Col(j int) []string {
 	col := make([]string, 0)
 	for i := 0; i < self.NRow(); i++ {
@@ -25,10 +30,12 @@ func (self *StringFrame) Col(j int) []string {
 	return col
 }
 
+// Number of rows
 func (self *StringFrame) NRow() int {
 	return len(self.labels)
 }
 
+// Number of columns
 func (self *StringFrame) NCol() int {
 	return len(self.labels[0])
 }