如果其他列满足某些条件，如何使数字为负数？

Question

如果我有几列

readarray -d '' arr < <(cmd | gawk -v RS='"[^"]*"' 'RT { gsub("\"", "", RT); printf RT"\0"}')

如果“交易类型”为借方？

，如何迭代列以使金额变为负数

Transaction Type    Amount
debit               1
credit              1

Answer 1

使用.loc

df.loc[df['TransactionType']=='debit','Amount']=-df.Amount
df
Out[376]: 
  TransactionType  Amount
0           debit      -1
1          credit       1

Answer 2

(-1) ** True为我们提供了-1，(-1) ** False为我们提供了1：

In [105]: df.Amount *= (-1) ** (df['Transaction Type'].eq('debit'))

In [106]: df
Out[106]:
  Transaction Type  Amount
0            debit      -1
1           credit       1

Answer 3

你想要的 df.Amount[df['Transaction Type']=='debit'] = - df.Amount