在一个 pandas DataFrame 中删除直到某个数值的行。

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英文:

Drop rows in a pandas DataFrame up to a certain value

问题

I only want to keep the rows that have a date greater or equal to 2014-10-26. The result should be something like the following table:

artist date
Drake 2014-10-26
Eminem 2014-10-26
Taylor Swift 2014-10-26
Kendrick Lamar 2014-10-26
Rihanna 2014-11-02
Ed Sheeran 2014-11-02
Kanye West 2014-11-02
Lime Cordiale 2014-11-02

I tried using pandas .drop() method like in the following line:

dataset = pd.read_csv("charts.csv")
dataset = pd.DataFrame(dataset)
dataset = dataset.drop(dataset.loc[dataset['date'] <= "2014-10-19", :])

but after executing I get the following error:

KeyError: "['track_id', 'name', 'country', 'date', 'position', 'streams', 'artists', 'artist_genres', 'duration', 'explicit'] not found in axis"

英文:

I'm currently working with a pandas data frame, with approximately 80000 rows, like the following one:

artist date
Drake 2014-10-12
Kendrick Lamar 2014-10-12
Ed Sheeran 2014-10-12
Maroon 5 2014-10-12
Rihanna 2014-10-19
Foo Fighters 2014-10-19
Bad Bunny 2014-10-19
Eminem 2014-10-19
Drake 2014-10-26
Eminem 2014-10-26
Taylor Swift 2014-10-26
Kendrick Lamar 2014-10-26
Rihanna 2014-11-02
Ed Sheeran 2014-11-02
Kanye West 2014-11-02
Lime Cordiale 2014-11-02

I only want to keep the rows that have a date greater or equal to 2014-10-26. The result should be something like the following table:

artist date
Drake 2014-10-26
Eminem 2014-10-26
Taylor Swift 2014-10-26
Kendrick Lamar 2014-10-26
Rihanna 2014-11-02
Ed Sheeran 2014-11-02
Kanye West 2014-11-02
Lime Cordiale 2014-11-02

I tried using pandas .drop() method like in the following line:

    dataset = pd.read_csv(&quot;charts.csv&quot;)
    dataset = pd.DataFrame(dataset)
    dataset = dataset.drop(dataset.loc[dataset[&#39;date&#39;] &lt;= &quot;2014-10-19&quot;, :])

but after executing I get the following error:

KeyError: &quot;[&#39;track_id&#39;, &#39;name&#39;, &#39;country&#39;, &#39;date&#39;, &#39;position&#39;, &#39;streams&#39;, &#39;artists&#39;, &#39;artist_genres&#39;, &#39;duration&#39;, &#39;explicit&#39;] not found in axis&quot;

答案1

得分: 0

不确定您遇到了什么错误,您必须提到错误日志。

无论如何,您可以使用索引来删除行,通过筛选数据获取索引,然后删除它:

indexx = dataset[dataset['date'] <= "2014-10-19"].index
dataset.drop(indexx, inplace=True)
英文:

not sure what error you got you must have to mentioned error log.

Anyway
You can use index for drop rows, get index by filter data and then drop it

indexx = dataset[ dataset[&#39;date&#39;] &lt;= &quot;2014-10-19&quot;  ].index
dataset.drop(indexx , inplace=True)

答案2

得分: 0

你可以使用以下代码:

last_date_to_drop = pd.to_datetime("2014-10-19")
dataset["date"] = pd.to_datetime(dataset["date"])
dataset = dataset.loc[dataset["date"].gt(last_date_to_drop)].copy()

不需要进行排序或删除操作,只需按照上述方式对数据框进行子集化并复制。

此外,"drop" 不是你想象中的那样操作。它不会按行值删除,而是按列或索引标签删除。

英文:

You could use:

last_date_to_drop = pd.to_datetime(&quot;2014-10-19&quot;)
dataset[&quot;date&quot;] = pd.to_datetime(dataset[&quot;date&quot;])
dataset = dataset.loc[dataset[&quot;date&quot;].gt(last_date_to_drop)].copy()

You don't need to sort or drop. Just subset the dataframe and copy as above.

Also drop is not what you think it will do. It won't drop by row values, it drops by column or index labels.

答案3

得分: 0

import pandas as pd

df = pd.DataFrame({'artist':['Drake', 'Kendrick Lamar', 'Kendrick Lamar', 'Drake'],
                   'date':['2014-10-12', '2014-10-12', '2014-10-26', '2014-10-26']})

# Be cautious : sort first
df = (df.sort_values(by='date', key=lambda t: pd.to_datetime(t, format='%Y-%m-%d')) 
        .drop_duplicates(subset=['artist'], keep='last'))

print(df)
#            artist        date
# 2  Kendrick Lamar  2014-10-26
# 3           Drake  2014-10-26
英文:
import pandas as pd

df = pd.DataFrame({&#39;artist&#39;:[&#39;Drake&#39;, &#39;Kendrick Lamar&#39;, &#39;Kendrick Lamar&#39;, &#39;Drake&#39;],
                   &#39;date&#39;:[&#39;2014-10-12&#39;, &#39;2014-10-12&#39;, &#39;2014-10-26&#39;, &#39;2014-10-26&#39;]})

# Be cautious : sort first
df = (df.sort_values(by=&#39;date&#39;, key=lambda t: pd.to_datetime(t, format=&#39;%Y-%m-%d&#39;)) 
        .drop_duplicates(subset=[&#39;artist&#39;], keep=&#39;last&#39;))

print(df)
#            artist        date
# 2  Kendrick Lamar  2014-10-26
# 3           Drake  2014-10-26

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  • 本文由 发表于 2023年2月16日 03:37:24
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