[Python]時刻データと数値データの変換メモ

数値データの時刻データへの変換

自分用メモ

dataframeでの数値と時系列データの変換に何度も間違えるのでメモ。
以下のようなデータ（秒）を時刻に直すような変換

> df['Time']
0        30620.5
1        39226.0
2        81318.5
3         3438.0
4        11108.5
          ...   
40916     3544.0
40917    37506.0
40918    23386.0
40919    37884.5
40920    24607.5
Name: Time, Length: 40921, dtype: float64

> df['Time']=pd.to_timedelta(df['Time'], unit='S') + pd.to_datetime('1900-01-01')
> df[Time]
0       1900-01-01 08:30:20.500
1       1900-01-01 10:53:46.000
2       1900-01-01 22:35:18.500
3       1900-01-01 00:57:18.000
4       1900-01-01 03:05:08.500
                  ...          
40916   1900-01-01 00:59:04.000
40917   1900-01-01 10:25:06.000
40918   1900-01-01 06:29:46.000
40919   1900-01-01 10:31:24.500
40920   1900-01-01 06:50:07.500
Name: Time, Length: 40921, dtype: datetime64[ns]

Ref : pandas.to_timedelta

unit
str, optional
Denotes the unit of the arg for numeric arg. Defaults to "ns".

Possible values
- ‘W’
- ‘D’ / ‘days’ / ‘day’
- ‘hours’ / ‘hour’ / ‘hr’ / ‘h’
- ‘m’ / ‘minute’ / ‘min’ / ‘minutes’ / ‘T’
- ‘S’ / ‘seconds’ / ‘sec’ / ‘second’
- ‘ms’ / ‘milliseconds’ / ‘millisecond’ / ‘milli’ / ‘millis’ / ‘L’
- ‘us’ / ‘microseconds’ / ‘microsecond’ / ‘micro’ / ‘micros’ / ‘U’
- ‘ns’ / ‘nanoseconds’ / ‘nano’ / ‘nanos’ / ‘nanosecond’ / ‘N’

Changed in version 1.1.0: Must not be specified when arg context strings and errors="raise".