Question

我有一个带有以下列的pandas.DataFrame：＆＃39; date＆＃39;，＆＃39; payment＆＃39;，＆＃39; principal＆＃39;，＆＃39; interest＆＃39;并且＆＃39;平衡＆＃39;，其中＆＃39; date＆＃39;是一个索引。我需要计算所有日期的所有列，其中根据另一列计算一部分列，以及计算与前一行的余额相关的任何行。在这种情况下是否可以避免使用for-loop？感谢。

P.S。谢谢你们的要求！有一段我的代码（我是python中的新代码）：

from decimal import Decimal as dec
from pandas import Series, DataFrame
import numpy as np

# Some given constants:
FLAG = True
sz = 4
K = 2
N = sz - 1

# DataFrame object definition:
_dates = [date(2012, m, 15) for m in range(1, 13)]
s = Series(range(len(_dates)), index=_dates, name='num', dtype=Decimal)
s.index.names = ['_dates']

df1 = DataFrame(s)
df1['pir'] = np.full(sz, dec('0.01'), dtype=dec)
df1['repayment'] = np.full(sz, dec('0'), dtype=dec)
df1['repayment'][3] = dec('0.3')
df1['indexation'] = [dec('1'), dec('1.01'), dec('1.01'), dec('1.01125'), dec('1.01125')]

df2 = DataFrame(s)
df2['interest'] = np.full(sz, dec('0'), dtype=dec)
df2['principal'] = np.full(sz, dec('0'), dtype=dec)
df2['payment'] = np.full(sz, dec('0'), dtype=dec)
df2['balance'] = np.full(sz, dec('1'), dtype=dec)

# The relevant calculation script:
cumulative_indexation = np.cumprod(df1.indexation.values)
for pmt in range(1, sz):
    beginning_balance = df2.balance[pmt-1] * df1.indexation[pmt]
    df2.interest[pmt] = df1.pir[pmt] * beginning_balance
    if pmt >= K:
        df2.principal[pmt] = np.min([beginning_balance-df1.repayment[pmt], cumulative_indexation[pmt]/N])
        df2.payment[pmt] = df2.principal[pmt] + df2.interest[pmt]
    else:
        df2.payment[pmt] = df2.principal[pmt] + df2.interest[pmt]*FLAG
    df2.balance[pmt] = (beginning_balance + df2.interest[pmt]) - (df2.payment[pmt] + df1.repayment[pmt])

Pandas DataFrame列在每行与之前相关而没有for-loop时更新

0 个答案: