用于 if/then/else 的 Python/pandas 习语
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Python/pandas idiom for if/then/else
提问by bjornarneson
After performing calculations on an entire pandas dataframe, I need to go back and override variable calculations (often setting to zero) based on the value of another variable(s). Is there a more succinct/idiomatic way to perform this kind of operation?
在对整个 Pandas 数据帧执行计算后，我需要返回并根据另一个变量的值覆盖变量计算（通常设置为零）。有没有更简洁/惯用的方式来执行这种操作？
df['var1000'][df['type']==7] = 0
df['var1001'][df['type']==7] = 0
df['var1002'][df['type']==7] = 0
...
df['var1099'][df['type']==7] = 0
Is there a pandas-y way to do something like this?
有没有一种 Pandas-y 方法来做这样的事情？
if (df['type']==7):
df['var1000'] = 0
df['var1001'] = 0
df['var1002'] = 0
...
df['var1099'] = 0
采纳答案by BrenBarn
df.ix[df.type==7, ['var1001', 'var1002']] = 0
If you're doing it on all columns, you can just do df.ix[df.type==7] = 0. Or of course if you have a list of the columns whose values you want to replace, you can pass that list in the second slot:
如果您在所有列上都执行此操作，则只需执行df.ix[df.type==7] = 0. 或者当然，如果您有要替换其值的列的列表，您可以在第二个插槽中传递该列表：
columnsToReplace = ['var1001', 'var1002', ...]
df.ix[df.type==8, columnsToReplace] = 0
