编辑添加新列

Setitem语法现在可以在dask.dataframe中使用

Edit Add New Columns

Setitem syntax now works in dask.dataframe

df['z'] = df.x + df.y

旧答案:添加新列

您正确的说，setitem语法在 dask.dataframe .

df['c'] = ... # mutation not supported

如您所建议，您应该改用.assign(...).

As you suggest you should instead use .assign(...).

df = df.assign(c=df.a + df.b)

在您的示例中，您不必要地调用了.compute().通常，您只想在获得最终结果后才在最后调用计算.

In your example you have an unnecessary call to .compute(). Generally you want to call compute only at the very end, once you have your final result.

和以前一样，dask.dataframe不支持更改行.就并行代码而言，就地操作很难进行推理.目前，在这种情况下，dask.dataframe没有很好的替代操作.我提出了问题#653 来讨论该主题.

As before, dask.dataframe does not support changing rows in place. Inplace operations are difficult to reason about in parallel codes. At the moment dask.dataframe has no nice alternative operation in this case. I've raised issue #653 for conversation on this topic.