python - Pandas 读取 sql 整数变成 float

Question

我遇到一个问题，当我使用pandas读取Mysql表时，一些列(见'to_nlc')以前是整数变成了 float (之后自动添加.0)。任何人都可以弄清楚吗？还是一些猜测？非常感谢!

Answer 1

问题是您的数据包含 NaN 值，因此 int 会自动转换为 float。

我想你可以检查NA type promotions :

When introducing NAs into an existing Series or DataFrame via reindex or some other means, boolean and integer types will be promoted to a different dtype in order to store the NAs. These are summarized by this table:

Typeclass   Promotion dtype for storing NAs
floating    no change
object      no change
integer     cast to float64
boolean     cast to object

While this may seem like a heavy trade-off, in practice I have found very few cases where this is an issue in practice. Some explanation for the motivation here in the next section.