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csv.go
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csv.go
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package mbt
import (
"encoding/csv"
"github.com/buckhx/diglet/util"
"github.com/deckarep/golang-set"
"io"
"os"
"strconv"
)
type FeatureSource interface {
Publish(workers int) (chan *Feature, error)
}
type GeoFields map[string]string
func (g GeoFields) Validate() bool {
return g.HasCoordinates() != g.HasShape() //xor
}
func (g GeoFields) HasCoordinates() bool {
return g["lat"] != "" && g["lon"] != ""
}
func (g GeoFields) HasShape() bool {
return g["shape"] != ""
}
type CsvSource struct {
path string
headers map[string]int
delimiter string
filter mapset.Set
fields GeoFields
}
func NewCsvSource(path string, filter []string, delimiter string, fields GeoFields) *CsvSource {
var set mapset.Set
if filter == nil || len(filter) == 0 {
set = nil
} else {
set = mapset.NewSet()
for _, k := range filter {
set.Add(k)
}
set.Add(fields["lat"])
set.Add(fields["lon"])
}
return &CsvSource{
path: path,
delimiter: delimiter,
filter: set,
fields: fields,
}
}
func (c *CsvSource) Publish(workers int) (features chan *Feature, err error) {
lines, err := c.publishLines()
if err != nil {
return
}
wg := util.WaitGroup(workers)
features = make(chan *Feature, 1000)
for i := 0; i < workers; i++ {
go func() {
defer wg.Done()
for line := range lines {
if feature, err := c.featureAdapter(line); err != nil {
util.Warn(err, "feature adapter")
} else {
features <- feature
}
}
}()
}
go func() {
wg.Wait()
defer close(features)
}()
return
}
func (c *CsvSource) publishLines() (lines chan []string, err error) {
//TODO optionally trim lines
f, err := os.Open(c.path)
if err != nil {
return
}
reader := csv.NewReader(f)
c.headers = readHeaders(reader, c.filter)
//TODO if err != nil
lines = make(chan []string, 100)
go func() {
defer close(lines)
defer f.Close()
for {
line, err := reader.Read()
if err == io.EOF {
break
}
if err != nil {
util.Warn(err, "line reading")
} else if line[c.headers[c.fields["lat"]]] == "" || line[c.headers[c.fields["geometry"]]] == "" {
continue
//err = util.Errorf("No coordinates %v", line)
//util.Warn(err, "no lat/lon")
} else {
lines <- line
}
}
}()
return
}
func (c *CsvSource) featureAdapter(line []string) (feature *Feature, err error) {
props := make(map[string]interface{}, len(c.headers)) //biggest malloc
for k, i := range c.headers {
props[k] = line[i]
}
switch {
case c.fields.HasCoordinates():
feature = NewFeature("point")
feature.Properties = props
lat, err := strconv.ParseFloat(line[c.headers[c.fields["lat"]]], 64)
if err != nil {
return nil, err
}
lon, err := strconv.ParseFloat(line[c.headers[c.fields["lon"]]], 64)
if err != nil {
return nil, err
}
point := NewShape(Coordinate{Lat: lat, Lon: lon})
feature.AddShape(point)
case c.fields.HasShape():
g := line[c.headers[c.fields["shape"]]]
shp, err := ShapeFromString(g)
if err != nil {
return nil, util.Errorf("Invalid shape format %+v", g)
}
switch {
case len(shp.Coordinates) == 0:
feature = NewFeature("point")
case len(shp.Coordinates) == 1:
feature = NewFeature("point")
case shp.Coordinates[0] == shp.Coordinates[len(shp.Coordinates)-1]: //closed
feature = NewFeature("polygon")
default:
feature = NewFeature("linestring")
}
feature.Properties = props
feature.AddShape(shp)
default:
err = util.Errorf("Invalid line")
}
return
}
func readHeaders(reader *csv.Reader, filter mapset.Set) (headers map[string]int) {
line, err := reader.Read()
util.Warn(err, "reading headers")
headers = make(map[string]int, len(line))
for i, k := range line {
//if _, ok := c.fields[k]; !ok {
k = util.Slugged(k, "_")
if filter == nil || filter.Contains(k) {
headers[k] = i
}
//}
}
util.Debug("Headers %v", headers)
return
}