[英]How to sort a pandas dataframe by date
我正在將數據從Google BigQuery導入到pandas數據框中,我想按日期對結果進行排序。 我的代碼如下:
import sys, getopt
import pandas as pd
from datetime import datetime
# set your BigQuery service account private private key
pkey ='#REMOVED#'
destination_table = 'test.test_table_2'
project_id = '#REMOVED#'
# write your query
query = """
SELECT date, SUM(totals.visits) AS Visits
FROM `#REMOVED#.#REMOVED#.ga_sessions_20*`
WHERE parse_date('%y%m%d', _table_suffix) between
DATE_sub(current_date(), interval 3 day) and
DATE_sub(current_date(), interval 1 day)
GROUP BY Date
"""
data = pd.read_gbq(query, project_id, dialect='standard', private_key=pkey, parse_dates=True, index_col='date')
date = data.sort_index()
data.info()
data.describe()
print(data.head())
我的輸出如下所示,因為您可以看到日期未排序。
<class 'pandas.core.frame.DataFrame'>
RangeIndex: 3 entries, 0 to 2
Data columns (total 2 columns):
date 3 non-null object
Visits 3 non-null int32
dtypes: int32(1), object(1)
memory usage: 116.0+ bytes
date Visits
0 20180312 207440
1 20180310 178155
2 20180311 207452
我已經閱讀了幾個問題,到目前為止嘗試了以下內容,導致我的輸出沒有變化:
index_col='date'
並添加date = data.sort_values(by='date')
headers = ['Date', 'Visits']
)和dypes( dtypes = [datetime, int]
)設置為我的read_gbq行( parse_dates=True, names=headers
) 我錯過了什么?
由於大部分工作都是在Google BigQuery方面完成的,我也會在那里進行排序:
query = """
SELECT date, SUM(totals.visits) AS Visits
FROM `#REMOVED#.#REMOVED#.ga_sessions_20*`
WHERE parse_date('%y%m%d', _table_suffix) between
DATE_sub(current_date(), interval 3 day) and
DATE_sub(current_date(), interval 1 day)
GROUP BY Date
ORDER BY Date
"""
這應該工作:
data.sort_values('date', inplace=True)
我設法通過將我的日期字段轉換為datetime對象來解決這個問題,我假設這將由parse_date=True
自動完成,但似乎只會解析現有的 datetime對象。
我在查詢后添加了以下內容,從我的日期字符串創建一個新的datetime列,然后我能夠使用data.sort_index()
並且它按預期工作:
time_format = '%Y-%m-%d'
data = pd.read_gbq(query, project_id, dialect='standard', private_key=pkey)
data['n_date'] = pd.to_datetime(data['date'], format=time_format)
data.index = data['n_date']
del data['date']
del data['n_date']
data.index.names = ['Date']
data = data.sort_index()
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