Question

我认为问题是使用翻译来帮助我翻译，因为我不会说话。

让我告诉我我的问题：

版本：python2.7

<pre>
sql = "select {}, {} from {} where {};".format(v1, v2, table, where)
        df = pd.read_sql(sql, app.config.get('sqlalchemy_engine'))
        df_dropna = df.dropna()
        dddd = df_dropna[v2]
        print type(dddd)
        print dddd[1]
        # print dddd # Have the answer
        print dddd[-1] # keyerror: -1
</pre>
error:
<pre>
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 2000, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 1991, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 1567, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 1988, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 1641, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 1544, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 1639, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 1625, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/opt/code/my_code/app4wp/app/views.py", line 136, in varianc_get
    print dddd[-1]
  File "/usr/local/lib/python2.7/dist-packages/pandas/core/series.py", line 601, in __getitem__
    result = self.index.get_value(self, key)
  File "/usr/local/lib/python2.7/dist-packages/pandas/indexes/base.py", line 2169, in get_value
    tz=getattr(series.dtype, 'tz', None))
  File "pandas/index.pyx", line 105, in pandas.index.IndexEngine.get_value (pandas/index.c:3567)

  File "pandas/index.pyx", line 113, in pandas.index.IndexEngine.get_value (pandas/index.c:3250)

  File "pandas/index.pyx", line 161, in pandas.index.IndexEngine.get_loc (pandas/index.c:4289)

  File "pandas/src/hashtable_class_helper.pxi", line 404, in pandas.hashtable.Int64HashTable.get_item (pandas/hashtable.c:8555)

  File "pandas/src/hashtable_class_helper.pxi", line 410, in pandas.hashtable.Int64HashTable.get_item (pandas/hashtable.c:8499)

KeyError: -1
</pre>

但： enter image description here

为什么？请问我该怎么做!!!

Answer 1

尝试使用.iloc：

print dddd.iloc[-1]

python 2.7 Series KeyError：-1

1 个答案: