pandas+mask

pandas中的mask函数是用于根据条件对数据进行遮蔽的函数。它可以接受一个条件表达式和一个替代值作为参数，并根据条件表达式的结果对数据进行替换。如果条件表达式为True，则使用替代值替换原始值；如果条件表达式为False，则保留原始值。

与mask函数类似的是where函数，不同之处在于where函数是在条件为False时进行替换，而mask函数是在条件为True时进行替换。

使用mask函数可以对DataFrame或Series对象中的数据进行条件过滤和替换，帮助我们进行数据清洗和处理。

相关问题

pandas.mask

pandas.mask()是pandas.DataFrame和pandas.Series的方法之一，用于根据条件对数据进行掩码操作。当对整个DataFrame或Series应用条件时，可以使用mask()方法。该方法将根据条件将不满足条件的元素替换为指定的值。例如，可以使用mask()方法将DataFrame中小于0的元素替换为-100。\[2\]\[3\]
#### 引用[.reference_title]
- *1* *2* *3* [53_Pandas中的条件替换值（where, mask）](https://blog.csdn.net/qq_18351157/article/details/127938064)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v91^insert_down28v1,239^v3^insert_chatgpt"}} ] [.reference_item]
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pandas mask

Pandas `mask` is a method that allows you to selectively replace values in a DataFrame or Series based on a condition. It is similar to the `where` method but with the opposite logic.

The basic syntax of `mask` is as follows:

df.mask(cond, other=)

Here, `cond` is the condition that determines which values to replace, and `other` is the value to replace with.

The `cond` can be a boolean expression, a callable, or a boolean DataFrame/Series of the same shape as the original DataFrame/Series. If the condition is True, the corresponding value in the DataFrame/Series will be replaced. Otherwise, it will be left unchanged.

If the `other` parameter is not provided, the default value is `NaN`. However, you can specify any other value or a DataFrame/Series of the same shape to replace the values that satisfy the condition.

Here's an example:

import pandas as pd
import numpy as np

data = {'A': [1, 2, 3, 4, 5],
        'B': [6, 7, 8, 9, 10]}
df = pd.DataFrame(data)

df_masked = df.mask(df > 3, -1)
print(df_masked)

Output:

   A   B
0  1   6
1  2   7
2  3   8
3 -1  -1
4 -1  -1

In this example, values greater than 3 in the DataFrame `df` are replaced with -1 using the `mask` method.