如何下载和解析csv文件在球拍？ [英] How to download and parse a csv file in Racket?

问题描述

如何在Racket中下载并解析csv文件？

How do I download and parse a csv file in Racket?

推荐答案

使用 get-pure-port 下载文件，并使用 Planet 图书馆 （require（planet neil / csv））解析。

Use get-pure-port to download the file, and use the Planet library (require (planet neil/csv)) to parse it.

以下示例下载并解析一个csv文件，其中包含了关于各种加拉帕戈斯群岛大小以及每个岛屿上发现了多少种类的
数据。

The following example downloads and parses a csv file containing data on the size of the various Galapagos islands and how many species were found on each island.

#lang racket
(require (planet neil/csv:1:=7) net/url)

(define galapagos-url 
  (string->url
   "http://www.stat.washington.edu/~handcock/536/Data/galapagos.csv"))

(define make-galapagos-csv-reader
  (make-csv-reader-maker
   '((separator-chars              #\,)
     (strip-leading-whitespace?  . #t)
     (strip-trailing-whitespace? . #t))))

(define (all-rows url make-reader)
  (define next-row (make-reader (get-pure-port url)))
  (define (loop)
    (define row (next-row))
    (if (empty? row)
        '()
        (cons row (loop))))
  (loop))

(all-rows galapagos-url make-galapagos-csv-reader)

返回的第一行是：

'(("Island"
   "Observed.species"
   "Native.species"
   "Area(km^2)"
   "Elevation(m)"
   "Distance.nearest.island(km)"
   "Distance.Santa.Cruz(km)"
   "Area.adj.island(km^2)")
  ("Baltra" "58" "23" "25.09" "" "0.6" "0.6" "1.84")
  ("Bartolome" "31" "21" "1.24" "109" "0.6" "26.3" "572.33")
  ("Caldwell" "3" "3" "0.21" "114" "2.8" "58.7" "0.78")

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