Robbie, It's hard to understand what you are doing.
The header says that there is no grade and sg is not where you say it is. Why are you using a channel? Why are you limiting the size of your input by reading the entire file into memory? And so on. My best guess is that you want to do something like this: Go Playground: https://play.golang.org/p/4Aok43E6AC Peter On Friday, February 24, 2017 at 8:58:52 AM UTC-5, Robbie Wright wrote: > > Hi this is my first go program and I am looking for some feedback and help > writing buffer to csv. To give you an idea of the structure of the data I > have run head on the input file gives output seen at the bottom. > > package main > > import ( > "bytes" > "encoding/csv" > "fmt" > "io" > "log" > "strconv" > "strings" > "bufio" > "io/ioutil" > ) > > // Calculate economic block value given a 40x20x12 block of density sg and > grade > func calculateE(sg float64, grade float64) float64 { > return 40 * 20 * 12 * sg * grade * 80 / 10 * 0.66 > } > > // Credit: Stack Overflow > func processCSV(rc io.Reader) (ch chan []string) { > ch = make(chan []string, 10) > go func() { > r := csv.NewReader(rc) > if _, err := r.Read(); err != nil { //read header > log.Fatal(err) > } > defer close(ch) > for { > rec, err := r.Read() > > if err != nil { > if err == io.EOF { > break > } > log.Fatal(err) > > } > ch <- rec > } > }() > return > } > > // Credit: Stack Overflow > func Readln(r *bufio.Reader) (string, error) { > var ( > isPrefix bool = true > err error = nil > line, ln []byte > ) > for isPrefix && err == nil { > line, isPrefix, err = r.ReadLine() > ln = append(ln, line...) > } > return string(ln), err > } > > func main() { > var buf bytes.Buffer > > w := csv.NewWriter(&buf) > file := "C:/ORIG.csv" > dat, _ := ioutil.ReadFile(file) > f := string(dat) > > for rec := range processCSV(strings.NewReader(f)) { > sg, err := strconv.ParseFloat(rec[17], 64) > grade, err := strconv.ParseFloat(rec[13], 64) > > if grade < 0 { > grade = 0 > } else { > grade = 0.1*grade > } > if sg < 0 { > sg = 0 > } > fmt.Println(grade) > // get economic block value > e := calculateE(sg, grade) > gradeStr := strconv.FormatFloat(grade, 'f', 8, 64) > sgStr := strconv.FormatFloat(sg, 'f', 8, 64) > eStr := strconv.FormatFloat(e, 'f', 8, 64) > rec := append(rec[0:4], eStr, sgStr, gradeStr) > if err = w.Write(rec); err != nil { > log.Fatal(err) > } > } > w.Flush() > if err := w.Error(); err != nil { > log.Fatal(err) > } > //fmt.Println(buf.String()) > //f2, err := os.Create("C:/Users/root/result.csv") > //defer f2.Close() > //writer := csv.NewWriter(f2) > //writer.Write(buf.String()) > } > > // 500mb csv with head of the data looks like: > const data = > `xcentre,ycentre,zcentre,xlength,ylength,zlength,fe_percent,fe_recovery,oxide,rescat,sg,mat_type_8,fillpc,mass_recovery,mass_recovery_percent,air,al2o3,cao,k2o,loi,mgo,mno,phos,sio2,tio2 > 556960.000,6319980.000,-1100.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,91,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 557000.000,6319980.000,-1100.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,91,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 556960.000,6320000.000,-1100.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,91,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 557000.000,6320000.000,-1100.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,91,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 556960.000,6319980.000,-1088.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,100,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 557000.000,6319980.000,-1088.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,100,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 556960.000,6320000.000,-1088.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,100,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 557000.000,6320000.000,-1088.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,100,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > 557040.000,6319980.000,-1100.000,40.000,20.000,12.000,-99.00000000,66.00000000,-99,4,2.84999990,2,91,0.00000000,0.00000000,0,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000,0.00000000 > ` > > > > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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