将多行数据循环到数据帧中的单行

Question

我正在从多行文本文件中提取数据点，并尝试将组数据添加到数据框中的单行，但我将每个数据点放在自己的行上，我想将其展平为 2 行 group1 和组2。我是Python新手。另外，如果有一种更有效的方法来做到这一点，那就太好了。我已经尝试过

groupby()

但这似乎不起作用？预先感谢。

import pandas as pd

data = """
Jan 2024
Group1 02/02/2024
dog 10 20
cat 21 32
Group2 05/02/2024
dog 23 45
cat 45 65
owl 24 12
monthly
Admin 02 22
clean 05 32
"""

extract = []
dog, cat, owl = [], [], []
for line in data.splitlines():
    a = c = e = ''
    # print(line)
    if 'Group' in line:
        group = line.rsplit()[0]
    
    if 'dog' in line or 'cat' in line or 'owl' in line:
        if line.startswith("dog"):
            dog, a, b = line.split()
        elif line.startswith("cat"):
            cat, c, d = line.split()
        elif line.startswith("owl"):
            owl, e, f = line.split()
        
        extract.append({
            'group': group,
            'dog': a,
            'cat': c,
            'owl': e
        })

df = pd.DataFrame(extract)
df = df[['group', 'dog', 'cat', 'owl']]
print(df)

目前我得到以下信息：

    group dog cat owl
0  Group1  10
1  Group1      21
2  Group2  23
3  Group2      45
4  Group2          24

我想要的是：

   group dog cat owl
0  Group1  10 21
1  Group2  23 45  24 

Answer 1

您可以在构建数据框之前折叠行。这可以通过每组维护一个

dict

column_name->value

来实现，当新组开始时刷新它，并将其添加为之前的一行。不要忘记在最后添加一行。

extract = []
row = None

for line in data.splitlines():
    if 'Group' in line:
        if row is not None: # we have something to add
            extract.append(row)
        group = line.rsplit()[0]
        row = {'group': group} # new group starts - refreshing our dict
    
    if 'dog' in line or 'cat' in line or 'owl' in line:
        animal, val1, val2 = line.split()
        row[animal] = val1
        
if row is not None: # a final group
    extract.append(row)

df = pd.DataFrame(extract)
df = df[['group', 'dog', 'cat', 'owl']]
print(df)

输出：

    group dog cat  owl
0  Group1  10  21  NaN
1  Group2  23  45   24