Python:URL数据到csv读取

Question

我正在尝试将url请求的结果转换为Python中的CSV reader object。输出似乎正常，但出现以下错误：

    for study_id, sample_id, run_id in reader:
ValueError: not enough values to unpack (expected 3, got 1)

首先，我请求数据并将其转换为字符串数据：

req = urllib.request.Request(url=url_get_project_runs, headers={'Content-Type': 'text/plain'})
        res = urllib.request.urlopen(req)
        dec_res =  res.read().decode()
        sys.stderr.write(str(dec_res)) --> for the print see below
        return dec_res

印刷品将给出：

ERP001736,ERS494374,ERR598958
ERP001736,ERS494394,ERR598963
ERP001736,ERS494431,ERR598964
ERP001736,ERS494445,ERR599170
ERP001736,ERS494488,ERR598996
ERP001736,ERS494518,ERR598976
ERP001736,ERS494559,ERR598986
ERP001736,ERS494579,ERR599078
ERP001736,ERS494616,ERR598944
ERP001736,ERS494628,ERR599001
ERP001736,ERS488919,ERR1701760

这对我来说似乎很好，因为项目是用逗号分隔的，“行”是完整的。 但是，如果我将此用作CSV读取器的输入，并尝试打印三列，如下所示：

reader = csv.reader(dec_res, delimiter=',')
        for study_id, sample_id, run_id in reader:
            print(study_id + ", " + sample_id + ", " + run_id)

将发生以下错误： ValueError: not enough values to unpack (expected 3, got 1)

我进一步测试了一些代码以发现问题：

 for row in reader:
            sys.stderr.write(str(row))

这将提供：

['E']['R']['P']['0']['0']['1']['7']['3']['6']['', '']['E']['R']['S']['4']['7']...etc

Answer 1

您正在将str传递给csv读取器，它需要一行一行的iterable。str是一个逐字符的iterable。用StringIO包装字符串或使用splitlines（或提供逐行iterable的任何其他方法）。你知道吗

import csv
from io import StringIO

dec_res = """ERP001736,ERS494374,ERR598958
ERP001736,ERS494394,ERR598963
ERP001736,ERS494431,ERR598964
ERP001736,ERS494445,ERR599170
ERP001736,ERS494488,ERR598996
ERP001736,ERS494518,ERR598976
ERP001736,ERS494559,ERR598986
ERP001736,ERS494579,ERR599078
ERP001736,ERS494616,ERR598944
ERP001736,ERS494628,ERR599001
ERP001736,ERS488919,ERR1701760"""

reader = csv.reader(StringIO(dec_res), delimiter=',')
#reader = csv.reader(dec_res.splitlines(), delimiter=',')

for study_id, sample_id, run_id in reader:
    print(study_id + ", " + sample_id + ", " + run_id)