How to get this specific shape for my data - go

Question

In Go, I'm using this function bars, err := custplotter.NewCandlesticks(data)
from here:
https://github.com/pplcc/plotext/tree/master/custplotter
It's expecting this shape for data:
[{2 16435 16458 16435 16446 1} {3 16446 16458 16435.04 16455 1} .....]
But my code below is creating my data in this shape instead:
[[2 16435 16458 16435 16446 1] [3 16446 16458 16435.04 16455 1] .....]
Which gives me this error message:
cannot use data (type [ ][ ]string) as type custplotter.TOHLCVer in argument to custplotter.NewCandlesticks:
[ ][ ]string does not implement custplotter.TOHLCVer (missing Len method)
I believe the problem is the data shape. How can i change my code to create the required data shape (with { } instead of [ ]) ?
//read excel file******************************************
xlsx, err := excelize.OpenFile("/media/Snaps/test snaps.xlsm")
if err != nil {
fmt.Println(err)
return
}
//read all rows into df
df := xlsx.GetRows("ticker_2")
//get only TOHLCV columns and 60 rows
df3 := make([][]string, 60) // create slice for 60 rows
idx := 0
for _, row := range df[1:61] { // read 60 rows
df3row := make([]string, 6) // create slice for 6 columns
copy(df3row, row[28:34]) // copy desired columns to new row slice
df3[idx] = df3row
idx++
}
All examples of slices i found in Go litterature uses only [ [ ], [ ] ]

Answer 1

as per https://github.com/pplcc/plotext/blob/68ab3c6e05c34baf5af21c9f5c3341f527a110ac/examples/tohlcvexampledata.go#L42
It seems that what you need is a custplotter.TOHLCVs which is just a slice of a struct of float64.
https://github.com/pplcc/plotext/blob/master/custplotter/tohlcv.go:
type TOHLCVer interface {
// Len returns the number of time, open, high, low, close, volume tuples.
Len() int
// TOHLCV returns an time, open, high, low, close, volume tuple.
TOHLCV(int) (float64, float64, float64, float64, float64, float64)
}
// TOHLCVs implements the TOHLCVer interface using a slice.
type TOHLCVs []struct{ T, O, H, L, C, V float64 }
so basically your solution could resemble this:
df3 := make(TOHLCVs, 60) // create slice for 60 rows
idx := 0
for _, row := range df[1:61] { // read 60 rows
df3[idx].T, err = strconv.ParseFloat(row[28], 64)
df3[idx].O, err = strconv.ParseFloat(row[29], 64)
df3[idx].H, err = strconv.ParseFloat(row[30], 64)
df3[idx].L, err = strconv.ParseFloat(row[31], 64)
df3[idx].C, err = strconv.ParseFloat(row[32], 64)
df3[idx].V, err = strconv.ParseFloat(row[33], 64)
idx++
}
Or you could just implement the TOHLCVer interface too :)
type SlicesOfTOHLCV [][6]float64
func (s SlicesOfTOHLCV) Len() int {
return len(s)
}
func (s SlicesOfTOHLCV) TOHLCV(i int) (float64, float64, float64, float64, float64) {
return s[i][0], s[i][1], s[i][2], s[i][3], s[i][4], s[i][5]
}
mySlice := make(SlicesOfTOHLCV, 60)
i := 0
for _, row := range df[1:61] {
mySlice[i] = [6]float64{}
for j := 0; j < 6; j ++ {
mySlice[i][j], err = strconv.ParseFloat(row[28+j], 64)
if err != nil {
panic(err)
}
}
i ++
}