Question

我希望通过df解析并根据条件返回特定的行。具体来说，对于等于String的{{1}}列，我希望返回下一个等于A的下一行。如果这些值在下一个A之前都不存在，那么我希望返回一条消息，指出'B','C' or 'D' ID字符串或类似的内容。

注意：此处不适用使用No item found for: ：

isin

因为我只想返回Item = ['A','B','C','D'] df = df[df['String'].isin(Item)]之后出现的'B','C' or 'D'的 first 字符串。我不希望这些字符串出现在所有位置的全部。我还想确定A是否存在，但在下一个A之前不跟随'B','C' or 'D'。

预期输出：

import pandas as pd

df1 = pd.DataFrame({
    'String' : ['A','F','B','C','D','A','X','C','B','D','A','Y','A','C','A','D','C','B'],                  
    'ID' : [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18],                         
        })

mask = df1.loc[df1['String'] == 'A', 'ID']

# Next value required
# Something like. where mask == True find next row equal to val in item list.
# If None: print(No item found for: ID)
item = ['B','C','D']

Answer 1

这是一个解决方案，为清晰起见，需要执行几个步骤：

df1["is_a"] = df1.String == "A"
df1["a_group"] = df1.is_a.cumsum()

def foo(s):
    matches = s[s.String.isin(["B", "C", "D"]) ]
    if len(matches):
        return s.loc[[s.index[0], matches.index[0]]]
    else: 
        print(f"No match for A in location {s.index[0]}")
    
    
df1.groupby("a_group").apply(foo)

输出为：

No match for A in location 10

           String  ID   is_a  a_group
a_group                              
1       0       A   1   True        1
        2       B   3  False        1
2       5       A   6   True        2
        7       C   8  False        2
4       12      A  13   True        4
        13      C  14  False        4
5       14      A  15   True        5
        15      D  16  False        5

Answer 2

使用item = ['A', 'B','C','D'] # filter df df1 = df1.loc[df1.String.isin(item)] # find missing ID's using shift for line in df1[(df1.String == 'A') & (df1.String.shift(-1) =='A')].iterrows(): print(f'No item found for: ID {line[1].ID}') # find final df using shift print(df1.loc[(df1.String == 'A') | ((df1.String.shift(1) == 'A') & (df1.String.isin(item)))]) #prints No item found for: ID 11 String ID 0 A 1 2 B 3 5 A 6 7 C 8 10 A 11 12 A 13 13 C 14 14 A 15 15 D 16

的解决方案

@mixin fade-in {
    opacity: 1;
    animation-name: fadeInOpacity;
    animation-iteration-count: 1;
    animation-timing-function: ease-in;
    animation-duration: 2s;
}

@keyframes fadeInOpacity {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}

其中col等于x，返回列表中的下一个有序值-熊猫

2 个答案: