`DataFrame` 行的内存高效过滤 [英] Memory-efficient filtering of `DataFrame` rows
问题描述
我有一个很大的 DataFrame
对象(1,440,000,000 行).我在内存(交换包括)限制下操作.
我需要提取具有特定字段值的行的子集.但是,如果我喜欢那样:
<预><代码>>>>SUBSET = DATA[DATA.field == value]我以 MemoryError
异常或崩溃结束.有什么方法可以显式过滤行 - 无需计算中间掩码(DATA.field == value
)?
我找到了 DataFrame.filter() 和 DataFrame.select() 方法,但它们对列标签/行索引而不是行数据进行操作.
使用 query
,应该会快一点:
df = df.query("field == value")
I have a large DataFrame
object (1,440,000,000 rows). I operate at memory (swap includet) limit.
I need to extract a subset of the rows with certain value of a field. However if i do like that:
>>> SUBSET = DATA[DATA.field == value]
I end with either MemoryError
exception or crash.
Is there any way to filter rows explicitely - without calculating intermediate mask (DATA.field == value
)?
I have found DataFrame.filter() and DataFrame.select() methods, but they operate on column labels/row indices rather than on the row data.
Use query
, it should be a bit faster:
df = df.query("field == value")
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