csv 文件以制表符分隔
文件1.csv:
id_album name date
001 Nevermind 24/09/1991
...
文件2.csv:
id_song id_album name
001 001 Smells Like Teen Spirit
002 001 In Bloom
...
我想获得此输出.csv :
id_album name date songs
001 Nevermind 24/09/1991 001,Smells Like Teen Spirit,002,In Bloom,...
你看到一种在Bash(最好)或Python中做到这一点的方法吗?
我的csv文件中有很多记录(数百万行)。
编辑
我尝试加入/sed/awk,但无法管理1到N的关系
发现 awk 语言:
awk -F'[[:space:]][[:space:]]+' 'NR==FNR{ if(NR>1) a[$2]=($2 in a? a[$2]",":"")$1","$3; next}
FNR==1{ print $0,"songs" }
$1 in a{ print $0,a[$1] }' file2.csv OFS='t' file1.csv > output.csv
output.csv
内容:
id_album name date songs
001 Nevermind 24/09/1991 001,Smells Like Teen Spirit,002,In Bloom
TL;DR
from io import StringIO
file1 = """id_album,name,date
001,Nevermind,24/09/1991"""
file2 = """id_song,id_album,name
001,001,Smells Like Teen Spirit
002,001,In Bloom"""
df1 = pd.read_csv(StringIO(file1))
df1 = df1.rename(columns={'name':'album_name'})
df2 = pd.read_csv(StringIO(file2))
df2 = df2.rename(columns={'name':'song_name'})
df3 = df1.merge(df2, on='id_album')
df4 = pd.DataFrame(list({album['id_album'].unique()[0]:','.join(list(album[['id_song', 'song_name']].astype(str).stack())) for idx, album in df3.groupby(['id_album'])}.items()), columns=['id_album', 'song_id_name'])
df_want = df1.merge(df4)
[输出]:
>>> df_want
id_album album_name date song_id_name
0 1 Nevermind 24/09/1991 1,Smells Like Teen Spirit,2,In Bloom
在长
鉴于:
>>> from io import StringIO
>>> file1 = """id_album,name,date
... 001,Nevermind,24/09/1991"""
>>> file2 = """id_song,id_album,name
... 001,001,Smells Like Teen Spirit
... 002,001,In Bloom"""
>>> df1 = pd.read_csv(StringIO(file1))
>>> df1 = df1.rename(columns={'name':'album_name'})
>>> df2 = pd.read_csv(StringIO(file2))
>>> df2 = df2.rename(columns={'name':'song_name'})
>>> df1
id_album album_name date
0 1 Nevermind 24/09/1991
>>> df2
id_song id_album name
0 1 1 Smells Like Teen Spirit
1 2 1 In Bloom
首先合并id_album
列上的 2 个数据帧:
>>> df3 = df1.merge(df2, on='id_album')
>>> df3
id_album album_name date id_song song_name
0 1 Nevermind 24/09/1991 1 Smells Like Teen Spirit
1 1 Nevermind 24/09/1991 2 In Bloom
现在来看一些pandas
技巧:
1. First group the rows by the `id_album` column:
2. In each group, get the `id_song` and `song_name` columns and stack them
>> [','.join(list(album[['id_song', 'song_name']].astype(str).stack())) for idx, album in df3.groupby(['id_album'])]
['1,Smells Like Teen Spirit,2,In Bloom']
以类似的方式,从.groupby()
获取album_name:
>>> [album['album_name'].unique()[0] for idx, album in df3.groupby(['id_album'])]
['Nevermind']
让我们将这两个groupby
操作结合起来:
>>> {album['album_name'].unique()[0]:','.join(list(album[['id_song', 'song_name']].astype(str).stack())) for idx, album in df3.groupby(['id_album'])}
{'Nevermind': '1,Smells Like Teen Spirit,2,In Bloom'}
>>> album2songs = {album['album_name'].unique()[0]:','.join(list(album[['id_song', 'song_name']].astype(str).stack())) for idx, album in df3.groupby(['id_album'])}
将该album2songs
放入数据帧:
>>> df4 = pd.DataFrame(list(album2songs.items()), columns=['album_name', 'song_id_name'])
>>> df4
album_name song_id_name
0 Nevermind 1,Smells Like Teen Spirit,2,In Bloom
现在加入df1
并df4
:
>>> df1.merge(df4)
id_album album_name date song_id_name
0 1 Nevermind 24/09/1991 1,Smells Like Teen Spirit,2,In Bloom
顺便说一句,@RomanPerekhrest awk
解决方案更酷!