Shapely循环不创建Linestring

Question

我正在尝试将元组从dataframe转换为一行字符串。这是从csv文件导入的数据文件的一部分。

   Unnamed: 0      name     route                                              decode
0           0    Funshine!  ofosF|mqaShJ@?rLh@d@veCIVd@LbEJfJ^f@lE?Rp@^L~g...  '[(-105.28, 39.999), (-105.282, 39.998), (-105.282, 39.99), (-105.28, 39.995), (-105.282, 39.99), (etc)]'

如果我手动复制解码列的内容并将其粘贴到LineString()条件中，它将对其进行转换。我收到的错误张贴在下面。

line = LineString(df.decode[0])
print(line)

Traceback (most recent call last):
  File "shapely\speedups\_speedups.pyx", line 86, in shapely.speedups._speedups.geos_linestring_from_py
AttributeError: 'str' object has no attribute '__array_interface__'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:/Users/taylo/PycharmProjects/PermitProj/Polyline Decode.py", line 20, in <module>
    line = LineString(df.decode[1])
  File "C:\Users\taylo\Miniconda3\envs\ExcelPermitExe\lib\site-packages\shapely\geometry\linestring.py", line 48, in __init__
    self._set_coords(coordinates)
  File "C:\Users\taylo\Miniconda3\envs\ExcelPermitExe\lib\site-packages\shapely\geometry\linestring.py", line 97, in _set_coords
    ret = geos_linestring_from_py(coordinates)
  File "shapely\speedups\_speedups.pyx", line 166, in shapely.speedups._speedups.geos_linestring_from_py
AssertionError

我最终想要循环它，所以我将它设置为dataframe列解码。这是我为最终将行字符串写入列而创建的循环。

def linestringdecode(name, decode):
    try:
        return LineString(decode)
    except:
        print(name)
        return np.nan

df['decode'] = df.apply(lambda x: linestringdecode(x[1], x[3]), axis=1)

如何编写它，以避免此错误，并将元组转换为dataframe中的列？

Answer 1

答案在本节中找到。

https://gis.stackexchange.com/questions/358068/converting-to-linestring-using-dataframe-column/

df['decode'] = df.decode.apply(lambda row: LineString(eval(row)))

编辑: eval()使用起来很危险。确保您使用的是可信数据。

Answer 2

编辑最终解决方案

经过一些清理之后，结果是将列decode保存为字符串"[(1,1),(2,3),(4,4),(1,3)]"，该字符串首先需要转换为元组列表。在使用密集列表理解进行转换之后，LineString转换将按以下方式工作

df['decode'] = [eval(ele) for ele in df.decode.str.strip()[:]]
df['decode'] = df.apply(lambda x: linestringdecode(x[1], x[4]), axis=1)

Alternative进行此操作的另一个选项是已经修复了导入。通过在ast.literal_eval的帮助下直接将字符串转换为元组列表，如本SO Question中所建议的那样

import ast
df = pd.read_csv("Test_Csv_With_List.csv", quotechar='"', sep=",",converters={4:ast.literal_eval})

​

编辑前的：--我尝试用下面的代码重现您的错误。然而，它运行完全良好，没有任何错误。

from shapely.geometry import LineString
import pandas as pd

def linestringdecode(name, decode):
    try:
        return LineString(decode)
    except:
        print(name)
        return np.nan

data = {'Unamed 0': [0,1],
        'name': ['test','test2'],
        'rote': ['Gibberish','moreGib'],
        'decode': [[(-105.27983, 40.06008), (-105.27984, 40.05827)],[(-23, 23), (-22, 24)]]}

df = pd.DataFrame(data)

# print(df)
df['decode'] = df.apply(lambda x: linestringdecode(x[1], x[3]), axis=1)

从您的错误消息AttributeError: 'str'中，我想我可以推断您的数据导入有问题。我的假设是，解码具有dtype对象，而不是list。

请验证函数linestringdecode()传递的参数decode是否为list类型，而不是字符串。