Python: csv阅读器的URL数据

Question

我试图用Python将url请求的结果转换为CSV读取器对象。输出似乎很好，但发生了以下错误：

    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

印刷品将显示如下：

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

这在我看来很好，因为项目是用逗号分隔的，“行”是完整的。但是，如果我使用它作为CSV读取器的输入，并尝试打印这三列，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))

这将使：

['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，它需要逐行迭代。str是一种逐字符迭代.用StringIO包装您的字符串，或者使用splitlines (或提供逐行迭代的任何其他方法)。

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)