对象似乎不是 8 位字符串路径或 Python 类文件对象

Question

我正在玩 Flask 和 Python 3.5。我想在网站上显示 matplotplib 图表。我找到了这个例子 https://gist.github.com/wilsaj/862153

由于我使用的是 Python 的 3.5 版本，因此我对 StringIO 部分做了一些小修改。

@bp.route("/simple.png")
def simple():
    import datetime
    import io
    import numpy as np
    import random

    from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
    from matplotlib.figure import Figure
    from matplotlib.dates import DateFormatter

    fig=Figure()
    ax=fig.add_subplot(111)
    x=[]
    y=[]
    now=datetime.datetime.now()
    delta=datetime.timedelta(days=1)
    for i in range(10):
        x.append(now)
        now+=delta
        y.append(random.randint(0, 1000))
    ax.plot_date(x, y, '-')
    ax.xaxis.set_major_formatter(DateFormatter('%Y-%m-%d'))
    fig.autofmt_xdate()
    canvas=FigureCanvas(fig)
    png_output = io.BytesIO()
    png_output_text = np.genfromtxt(png_output, delimiter=",")
    canvas.print_png(png_output_text)
    response=make_response(png_output_text.getvalue())
    response.headers['Content-Type'] = 'image/png'
    return response

我收到错误：

Traceback (most recent call last):
  File "c:\proofdevelopment\flask\flask\app.py", line 1988, in wsgi_app
    response = self.full_dispatch_request()
  File "c:\proofdevelopment\flask\flask\app.py", line 1641, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "c:\proofdevelopment\flask\flask\app.py", line 1544, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "c:\proofdevelopment\flask\flask\_compat.py", line 33, in reraise
    raise value
  File "c:\proofdevelopment\flask\flask\app.py", line 1639, in full_dispatch_request
    rv = self.dispatch_request()
  File "c:\proofdevelopment\flask\flask\app.py", line 1625, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "C:\ProofDevelopment\flask\examples\flaskr\flaskr\blueprints\flaskr.py", line 107, in simple
    canvas.print_png(png_output_text)
  File "C:\Users\nmartinez\AppData\Local\Continuum\miniconda3\envs\py35\lib\site-packages\matplotlib\backends\backend_agg.py", line 526, in print_png
    self.figure.dpi, metadata=metadata)
TypeError: Object does not appear to be a 8-bit string path or a Python file-like object

我只想运行那个 'simple' 例子，但我没能做到 :(

Answer 1

我不确定您为什么要添加 np.genfromtxt() 调用。以下几行创建内存中的文件对象就足够了；这些是视图函数中的最后几行，从您的 png_output 行开始：

png_output = io.BytesIO()
canvas.print_png(png_output)
response = make_response(png_output.getvalue())
response.headers['Content-Type'] = 'image/png'
return response

经过这些更改，代码生成了一个情节：

Answer 2

x_train=np.array(list(map(img_preprocess,x_train)))
x_valid=np.array(list(map(img_preprocess,x_valid)))
bit shows object-does-not-appear-to-be-a-8-bit-string-path-or-a-python-file-like-object

背后的问题是什么？

Answer 3

x_train=np.array(list(map(img_preprocess,x_train)))
x_valid=np.array(list(map(img_preprocess,x_valid)))

位显示对象不显示为 8 位字符串路径或-python-文件类对象

这个错误是因为你已经通过执行 x_train=np.array(list(map(img_preprocess,x_train))) 这一行改变了 x_train 的形状，所以 x_train 会不时更新，如果你给 x_train作为 x_train=np.array(list(map(img_preprocess,x_train))) 函数的输入，那么它会给出这个错误

解决方案：重新设置您的python内核和运行所有代码。

对象似乎不是 8 位字符串路径或 Python 类文件对象

Object does not appear to be a 8-bit string path or a Python file-like object

python

matplotlib

flask

python-3.5