問題描述
我有一個包含一些(數(shù)億)行的數(shù)據(jù)框.我想有效地將??日期時間轉(zhuǎn)換為時間戳.我該怎么做?
我的示例df:
df = pd.DataFrame(index=pd.DatetimeIndex(start=dt.datetime(2016,1,1,0,0,1),結(jié)束=dt.datetime(2016,1,2,0,0,1), 頻率='H')).reset_index().rename(columns={'index':'datetime'})df.head()約會時間0 2016-01-01 00:00:011 2016-01-01 01:00:012 2016-01-01 02:00:013 2016-01-01 03:00:014 2016-01-01 04:00:01現(xiàn)在我使用 .apply() 將日期時間逐個轉(zhuǎn)換為時間戳值，但如果我有一些(數(shù)億)行，則需要很長時間(幾個小時):
df['ts'] = df[['datetime']].apply(lambda x: x[0].timestamp(), axis=1).astype(int)df.head()日期時間 ts0 2016-01-01 00:00:01 14516028011 2016-01-01 01:00:01 14516064012 2016-01-01 02:00:01 14516100013 2016-01-01 03:00:01 14516136014 2016-01-01 04:00:01 1451617201上面的結(jié)果就是我想要的.
如果我嘗試使用 pandas.Series 的 .dt 訪問器，則會收到錯誤消息:
df['ts'] = df['datetime'].dt.timestamp<塊引用>
AttributeError: 'DatetimeProperties' 對象沒有屬性'時間戳'
如果我嘗試創(chuàng)建例如.使用 .dt 訪問器的日期時間的日期部分比使用 .apply() 快得多:
df['date'] = df['datetime'].dt.datedf.head()日期時間 ts 日期0 2016-01-01 00:00:01 1451602801 2016-01-011 2016-01-01 01:00:01 1451606401 2016-01-012 2016-01-01 02:00:01 1451610001 2016-01-013 2016-01-01 03:00:01 1451613601 2016-01-014 2016-01-01 04:00:01 1451617201 2016-01-01我想要類似時間戳的東西...
但我不太了解官方文檔:它談到轉(zhuǎn)換為時間戳" 但我沒有看到任何時間戳；它只是談?wù)撌褂?pd.to_datetime() 轉(zhuǎn)換為日期時間，而不是時間戳...
pandas.Timestamp 構(gòu)造函數(shù)也不起作用(返回以下錯誤):
df['ts2'] = pd.Timestamp(df['datetime'])<塊引用>
TypeError:無法將輸入轉(zhuǎn)換為時間戳
pandas.Series.to_timestamp 也做出了我想要的完全不同的東西:
df['ts3'] = df['datetime'].to_timestampdf.head()日期時間 ts ts30 2016-01-01 00:00:01 1451602801 <綁定方法 Series.to_timestamp of 0 2016...1 2016-01-01 01:00:01 1451606401 <綁定方法 Series.to_timestamp of 0 2016...2 2016-01-01 02:00:01 1451610001 <綁定方法 Series.to_timestamp of 0 2016...3 2016-01-01 03:00:01 1451613601 <綁定方法 Series.to_timestamp of 0 2016...4 2016-01-01 04:00:01 1451617201 <綁定方法 Series.to_timestamp of 0 2016...謝謝！！
我覺得你需要先轉(zhuǎn)換成 numpy array by values 并轉(zhuǎn)換為 int64 - 輸出在 ns，所以需要除以10 ** 9:
df['ts'] = df.datetime.values.astype(np.int64)//10 ** 9打印 (df)日期時間 ts0 2016-01-01 00:00:01 14516064011 2016-01-01 01:00:01 14516100012 2016-01-01 02:00:01 14516136013 2016-01-01 03:00:01 14516172014 2016-01-01 04:00:01 14516208015 2016-01-01 05:00:01 14516244016 2016-01-01 06:00:01 14516280017 2016-01-01 07:00:01 14516316018 2016-01-01 08:00:01 14516352019 2016-01-01 09:00:01 145163880110 2016-01-01 10:00:01 145164240111 2016-01-01 11:00:01 145164600112 2016-01-01 12:00:01 145164960113 2016-01-01 13:00:01 145165320114 2016-01-01 14:00:01 145165680115 2016-01-01 15:00:01 145166040116 2016-01-01 16:00:01 145166400117 2016-01-01 17:00:01 145166760118 2016-01-01 18:00:01 145167120119 2016-01-01 19:00:01 145167480120 2016-01-01 20:00:01 145167840121 2016-01-01 21:00:01 145168200122 2016-01-01 22:00:01 145168560123 2016-01-01 23:00:01 145168920124 2016-01-02 00:00:01 1451692801to_timestamp 用于將 從周期索引轉(zhuǎn)換為日期時間索引.
I have a dataframe with some (hundreds of) million of rows. And I want to convert datetime to timestamp effectively. How can I do it?
My sample df:
df = pd.DataFrame(index=pd.DatetimeIndex(start=dt.datetime(2016,1,1,0,0,1),
end=dt.datetime(2016,1,2,0,0,1), freq='H'))
.reset_index().rename(columns={'index':'datetime'})
df.head()
datetime
0 2016-01-01 00:00:01
1 2016-01-01 01:00:01
2 2016-01-01 02:00:01
3 2016-01-01 03:00:01
4 2016-01-01 04:00:01
Now I convert datetime to timestamp value-by-value with .apply() but it takes a very long time (some hours) if I have some (hundreds of) million rows:
df['ts'] = df[['datetime']].apply(lambda x: x[0].timestamp(), axis=1).astype(int)
df.head()
datetime ts
0 2016-01-01 00:00:01 1451602801
1 2016-01-01 01:00:01 1451606401
2 2016-01-01 02:00:01 1451610001
3 2016-01-01 03:00:01 1451613601
4 2016-01-01 04:00:01 1451617201
The above result is what I want.
If I try to use the .dt accessor of pandas.Series then I get error message:
df['ts'] = df['datetime'].dt.timestamp
AttributeError: 'DatetimeProperties' object has no attribute 'timestamp'
If I try to create eg. the date parts of datetimes with the .dt accessor then it is much more faster then using .apply():
df['date'] = df['datetime'].dt.date
df.head()
datetime ts date
0 2016-01-01 00:00:01 1451602801 2016-01-01
1 2016-01-01 01:00:01 1451606401 2016-01-01
2 2016-01-01 02:00:01 1451610001 2016-01-01
3 2016-01-01 03:00:01 1451613601 2016-01-01
4 2016-01-01 04:00:01 1451617201 2016-01-01
I want something similar with timestamps...
But I don't really understand the official documentation: it talks about "Converting to Timestamps" but I don't see any timestamps there; it just talks about converting to datetime with pd.to_datetime() but not to timestamp...
pandas.Timestamp constructor also doesn't work (returns with the below error):
df['ts2'] = pd.Timestamp(df['datetime'])
TypeError: Cannot convert input to Timestamp
pandas.Series.to_timestamp also makes something totally different that I want:
df['ts3'] = df['datetime'].to_timestamp
df.head()
datetime ts ts3
0 2016-01-01 00:00:01 1451602801 <bound method Series.to_timestamp of 0 2016...
1 2016-01-01 01:00:01 1451606401 <bound method Series.to_timestamp of 0 2016...
2 2016-01-01 02:00:01 1451610001 <bound method Series.to_timestamp of 0 2016...
3 2016-01-01 03:00:01 1451613601 <bound method Series.to_timestamp of 0 2016...
4 2016-01-01 04:00:01 1451617201 <bound method Series.to_timestamp of 0 2016...
Thank you!!
I think you need convert first to numpy array by values and cast to int64 - output is in ns, so need divide by 10 ** 9:
df['ts'] = df.datetime.values.astype(np.int64) // 10 ** 9
print (df)
datetime ts
0 2016-01-01 00:00:01 1451606401
1 2016-01-01 01:00:01 1451610001
2 2016-01-01 02:00:01 1451613601
3 2016-01-01 03:00:01 1451617201
4 2016-01-01 04:00:01 1451620801
5 2016-01-01 05:00:01 1451624401
6 2016-01-01 06:00:01 1451628001
7 2016-01-01 07:00:01 1451631601
8 2016-01-01 08:00:01 1451635201
9 2016-01-01 09:00:01 1451638801
10 2016-01-01 10:00:01 1451642401
11 2016-01-01 11:00:01 1451646001
12 2016-01-01 12:00:01 1451649601
13 2016-01-01 13:00:01 1451653201
14 2016-01-01 14:00:01 1451656801
15 2016-01-01 15:00:01 1451660401
16 2016-01-01 16:00:01 1451664001
17 2016-01-01 17:00:01 1451667601
18 2016-01-01 18:00:01 1451671201
19 2016-01-01 19:00:01 1451674801
20 2016-01-01 20:00:01 1451678401
21 2016-01-01 21:00:01 1451682001
22 2016-01-01 22:00:01 1451685601
23 2016-01-01 23:00:01 1451689201
24 2016-01-02 00:00:01 1451692801
to_timestamp is used for converting from period to datetime index.
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