Question

我想使用以下功能过滤数据帧

def isInRadius(position):
    latCheck = False
    lonCheck = False
    if position.lat < 0:
        latCheck = position.lat <= upperLat and position.lat >= lowerLat
    else:
        latCheck = position.lat >= upperLat and position.lat <= lowerLat

    if not latCheck:
        return False

    if position.lon < 0:
        lonCheck = position.lon <= righterLon and position.lon >= lefterLon
    else:
        lonCheck = position.lon >= righterLon and position.lat <= lefterLon

    return latCheck and lonCheck

数据框的列数比'lat'和'lon'多，但我想根据上面函数实现的逻辑用那2个过滤。

我尝试了dataFrame.filter(lambda x: isInRadius(x))，dataFrame.filter(isInRadius)和dataFrame.filter(lambda x: isInRadius(x.iLoc[0]))等方法，但均无效果，导致出现错误“ TypeError：'function'对象不可迭代”

我应该怎么做？

在C＃上我会做

var filtered = myCollection.Where(x => isInRadius(x));

Answer 1

只需使用熊猫数据框的.apply功能

df[df.apply(isInRadius, 1)]

Answer 2

无需使用申请

import pandas as pd

df2 =pd.DataFrame({'lookup_id':['a','a','c','c','c'],'val':[1,1,1,1,1]})
print(df2)

  lookup_id  val
0         a    1
1         a    1
2         c    1
3         c    1
4         c    1

# Replace this with whatever your function actually does
def val_is_a(r):
    return r['lookup_id'] =='a'

df2.loc[lambda df : val_is_a(df)]

    lookup_id   val
0   a           1
1   a           1

如何使用函数过滤数据帧？

2 个答案: