remove options for reading files. update docs and learn more about se…

…ction4(surfaces)

griblib/data_test.go

@@ -1,7 +1,6 @@
 package griblib
 
 import (
-	"math"
 	"os"
 	"testing"
 )
@@ -12,10 +11,7 @@ func Test_read_integrationtest_file(t *testing.T) {
 	if fileOpenErr != nil {
 		t.Fatal("Grib file for integration tests not found")
 	}
-	messages, messageParseErr := ReadMessages(testFile, Options{
-		MaximumNumberOfMessages: math.MaxInt32,
-		Discipline:              -1,
-	})
+	messages, messageParseErr := ReadMessages(testFile)
 
 	if messageParseErr != nil {
 		t.Fatal("Error reading messages: ", messageParseErr.Error())

griblib/filters.go

@@ -64,7 +64,8 @@ func filteredGrid(grid0 *Grid0, filter GeoFilter) *Grid0 {
 }
 
 func isEmpty(geoFilter GeoFilter) bool {
-	return geoFilter == GeoFilter{MinLong: LongitudeStart, MaxLong: LongitudeEnd, MinLat: LatitudeNorth, MaxLat: LatitudeSouth}
+	return geoFilter == GeoFilter{MinLong: LongitudeStart, MaxLong: LongitudeEnd, MinLat: LatitudeNorth, MaxLat: LatitudeSouth} ||
+		geoFilter == GeoFilter{}
 }
 
 func filterValuesFromGeoFilter(message Message, filter GeoFilter) (*[]int64, error) {

griblib/filters_test.go

@@ -2,6 +2,8 @@ package griblib
 
 import (
 	"testing"
+	"os"
+	"fmt"
 )
 
 func Test_calculcate_startStopIndexes(t *testing.T) {
@@ -91,3 +93,37 @@ func Test_filter_on_category(t *testing.T) {
 		t.Error("should have filtered when option is different from message")
 	}
 }
+
+func Test_temperature_layers(t *testing.T) {
+	file, err := os.Open("integrationtestdata/gfs.t00z.pgrb2.2p50.f006")
+	if err != nil {
+		t.Fatal("Could not open testfile")
+	}
+	messages, msgErr := ReadMessages(file)
+
+	if msgErr != nil {
+		t.Fatal("Error reading messages from testfile")
+	}
+	if len(messages) != 77 {
+		t.Errorf("expected 77 messages, got %d\n", len(messages))
+	}
+
+	filtered := Filter(messages, Options{Discipline: 0 , Category: 0})
+
+	if len(filtered) != 11 {
+		t.Errorf("expected 11 messages, got %d\n", len(filtered))
+	}
+
+	fmt.Println("layers for temperature ")
+	for _, f := range filtered {
+		fmt.Printf("s1:%d\ts2:%d\tt1:%d\tt2:%d\tv1:%d(meter over sea-level?)\tv2:%d\n",
+			f.Section4.ProductDefinitionTemplate.FirstSurface.Scale,
+			f.Section4.ProductDefinitionTemplate.SecondSurface.Scale,
+			f.Section4.ProductDefinitionTemplate.FirstSurface.Type,
+			f.Section4.ProductDefinitionTemplate.SecondSurface.Type,
+			f.Section4.ProductDefinitionTemplate.FirstSurface.Value,
+			f.Section4.ProductDefinitionTemplate.SecondSurface.Value,
+				)
+	}
+
+}

griblib/products.go

@@ -75,9 +75,9 @@ type TimeRangeSpecification struct {
 	TimeIncrementBetweenSuccessiveField                    uint32 `json:"timeIncrementBetweenSuccessiveField"`                    // 55-58
 }
 
-//Surface describes a surface for a product
+//Surface describes a surface for a product, see http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_table4-5.shtml
 type Surface struct {
-	Type  uint8  `json:"type"`
+	Type  uint8  `json:"type"` // type 220: Planetary Boundary Layer
 	Scale uint8  `json:"scale"`
-	Value uint32 `json:"value"`
+	Value uint32 `json:"value"` // e.g. meters above sea-level
 }

griblib/sections.go

@@ -8,7 +8,7 @@ import (
 	"strings"
 )
 
-//Message is poorly documented other than code
+//Message is the entire message for a data-layer
 type Message struct {
 	Section0 Section0
 	Section1 Section1
@@ -20,17 +20,17 @@ type Message struct {
 	Section7 Section7
 }
 
-//Options is poorly documented other than code
+//Options is used to filter messages.
 type Options struct {
 	Operation               string    `json:"operation"`
-	Discipline              int       `json:"discipline"`
+	Discipline              int       `json:"discipline"` // -1 means all disciplines
 	DataExport              bool      `json:"dataExport"`
-	Category                int       `json:"category"`
+	Category                int       `json:"category"`   // -1 means all categories
 	Filepath                string    `json:"filePath"`
 	ReduceFilePath          string    `json:"reduceFilePath"`
 	ExportType              int       `json:"exportType"`
 	MaximumNumberOfMessages int       `json:"maximumNumberOfMessages"`
-	GeoFilter               GeoFilter `json:"geoFilter"`
+	GeoFilter               GeoFilter `json:"geoFilter"`  // empty filter , GeoFilter{},  means no filter
 }
 
 const (
@@ -43,7 +43,7 @@ const (
 )
 
 //ReadMessages reads all message from gribFile
-func ReadMessages(gribFile io.Reader, options Options) (messages []Message, err error) {
+func ReadMessages(gribFile io.Reader) (messages []Message, err error) {
 
 	for {
 		message, messageErr := ReadMessage(gribFile)
@@ -55,13 +55,10 @@ func ReadMessages(gribFile io.Reader, options Options) (messages []Message, err
 			return messages, err
 		}
 		messages = append(messages, message)
-		if options.MaximumNumberOfMessages > 0 && len(messages) >= int(options.MaximumNumberOfMessages) {
-			return messages, nil
-		}
 	}
 }
 
-//ReadMessage is poorly documented other than code
+//ReadMessage reads the actual messages from a gribfile-reader (io.Reader from either file, http or any other io.Reader)
 func ReadMessage(gribFile io.Reader) (message Message, err error) {
 
 	section0, headError := ReadSection0(gribFile)
@@ -88,7 +85,6 @@ func ReadMessage(gribFile io.Reader) (message Message, err error) {
 
 }
 
-//readMessage is poorly documented other than code
 func readMessage(gribFile io.Reader, section0 Section0) (message Message, err error) {
 
 	message.Section0 = section0
@@ -129,7 +125,7 @@ func readMessage(gribFile io.Reader, section0 Section0) (message Message, err er
 	}
 }
 
-//Section0 is poorly documented other than code
+//Section0 is the indicator section http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_sect0.shtml
 type Section0 struct {
 	Indicator     uint32 `json:"indicator"`
 	Reserved      uint16 `json:"reserved"`
@@ -138,7 +134,7 @@ type Section0 struct {
 	MessageLength uint64 `json:"messageLength"`
 }
 
-//ReadSection0 is poorly documented other than code
+//ReadSection0 reads Section0 from an io.reader
 func ReadSection0(reader io.Reader) (section0 Section0, err error) {
 	section0.Indicator = 255
 	err = binary.Read(reader, binary.BigEndian, &section0)
@@ -156,13 +152,8 @@ func ReadSection0(reader io.Reader) (section0 Section0, err error) {
 
 }
 
-//Section is poorly documented other than code
-type Section interface {
-	SectionNumber() uint8
-	String() string
-}
 
-//SectionHead is poorly documented other than code
+//SectionHead is the common header for each section1-8
 type SectionHead struct {
 	ByteLength uint32 `json:"byteLength"`
 	Number     uint8  `json:"number"`
@@ -275,7 +266,7 @@ func ReadSection3(f io.Reader) (section Section3, err error) {
 type Section4 struct {
 	CoordinatesCount                uint16   `json:"coordinatesCount"`
 	ProductDefinitionTemplateNumber uint16   `json:"productDefinitionTemplateNumber"`
-	ProductDefinitionTemplate       Product0 `json:"productDefinitionTemplate"` // FIXME
+	ProductDefinitionTemplate       Product0 `json:"productDefinitionTemplate"` // FIXME, support more products
 	Coordinates                     []byte   `json:"coordinates"`
 }
 
@@ -306,7 +297,7 @@ func ReadSection4(f io.Reader) (section Section4, err error) {
 type Section5 struct {
 	PointsNumber       uint32 `json:"pointsNumber"`
 	DataTemplateNumber uint16 `json:"dataTemplateNumber"`
-	DataTemplate       Data3  `json:"dataTemplate"` // FIXME
+	DataTemplate       Data3  `json:"dataTemplate"` // FIXME, support more data-types
 }
 
 //ReadSection5 is poorly documented other than code

main.go

@@ -112,7 +112,7 @@ func reduceToFile(gribFile io.Reader, options griblib.Options) {
 }
 
 func parse(gribFile io.Reader, options griblib.Options) {
-	messages, err := griblib.ReadMessages(gribFile, options)
+	messages, err := griblib.ReadMessages(gribFile)
 
 	if err != nil {
 		fmt.Printf("Error reading all messages in gribfile: %s", err.Error())