应用这两个数据帧时数据帧位置错误

Question

我正在尝试将这两个数据帧（data2 和交易）放在一起以使其看起来像这样 https://i.stack.imgur.com/pR8bW.png:

数据2：

            Close
2015-08-28  113.290001
2015-08-31  112.760002
2015-09-01  107.720001
2015-09-02  112.339996
2015-09-03  110.370003
2015-09-04  109.269997
2015-09-08  112.309998
2015-09-09  110.150002
2015-09-10  112.570000
2015-09-11  114.209999

交易：

               Trades
2015-08-28     3.0
2015-08-31     3.0
2015-09-01     3.0
2015-09-02     3.0
2015-09-03     2.0

代码：

import matplotlib.pyplot as plt

fig = plt.figure()

ax1 = fig.add_subplot(111, ylabel='Portfolio value in $')

data2["Close"].plot(ax=ax1, lw=2.)

ax1.plot(data2.loc[trades.Trades == 2.0].index, data2.total[trades.Trades == 2.0],
         '^', markersize=10, color='m')
ax1.plot(data2.loc[trades.Trades == 3.0].index, 
         data2.total[trades.Trades == 3.0],
         'v', markersize=10, color='k')

plt.show()

但这会产生以下错误：

---------------------------------------------------------------------------
IndexingError                             Traceback (most recent call last)
<ipython-input-38-9cde686354a8> in <module>()
      7 data2["Close"].plot(ax=ax1, lw=2.)
      8 
----> 9 ax1.plot(data2.loc[trades.Trades == 2.0].index, data2.total[trades.Trades == 2.0],
     10          '^', markersize=10, color='m')
     11 ax1.plot(data2.loc[trades.Trades == 3.0].index, 

3 frames
/usr/local/lib/python3.6/dist-packages/pandas/core/indexing.py in check_bool_indexer(index, key)
   2316         if mask.any():
   2317             raise IndexingError(
-> 2318                 "Unalignable boolean Series provided as "
   2319                 "indexer (index of the boolean Series and of "
   2320                 "the indexed object do not match)."

IndexingError: Unalignable boolean Series provided as indexer (index of the boolean Series and of the indexed object do not match).

Answer 1

两个数据帧的索引不同。我采用了为 data2 数据帧定义 masks 的方法，该数据帧基于 trades 数据帧中的值并且有效。

此外，您的示例代码引用了 total，但不存在。使用 Close

的更新

import pandas as pd
import io
import matplotlib.pyplot as plt

data2 = pd.read_csv(io.StringIO("""            Close
2015-08-28  113.290001
2015-08-31  112.760002
2015-09-01  107.720001
2015-09-02  112.339996
2015-09-03  110.370003
2015-09-04  109.269997
2015-09-08  112.309998
2015-09-09  110.150002
2015-09-10  112.570000
2015-09-11  114.209999"""), sep="\s+")

trades = pd.read_csv(io.StringIO("""               Trades
2015-08-28     3.0
2015-08-31     3.0
2015-09-01     3.0
2015-09-02     3.0
2015-09-03     2.0"""), sep="\s+")

# make sure it's dates
data2 = data2.reset_index().assign(index=lambda x: pd.to_datetime(x["index"])).set_index("index")
trades = trades.reset_index().assign(index=lambda x: pd.to_datetime(x["index"])).set_index("index")

fig = plt.figure()
ax1 = fig.add_subplot(111, ylabel='Portfolio value in $')

data2["Close"].plot(ax=ax1, lw=2.)

mask2 = data2.index.isin((trades.Trades == 2.0).index)
mask3 = data2.index.isin((trades.Trades == 3.0).index)

ax1.plot(data2.loc[mask2].index, data2.Close[mask2],
         '^', markersize=10, color='m')
ax1.plot(data2.loc[mask3].index, 
         data2.Close[mask3],
         'v', markersize=10, color='k')


plt.show()

输出

应用这两个数据帧时数据帧位置错误

error in dataframe loc when applying these two dataframes

python

pandas

dataframe

pandas-loc