在r中保存分隔列的数据框

Question

我试图将一个保存日期和时间戳的列分成2列。然而，我有保存它的问题。在本例中，数据框"four_row "正在控制台中打印，但没有这样保存。我正在努力理解如何将其保存为数据框架。

mydata <-read.csv("/Users/me/Some_Folder/big_csv_file.csv")
four_rows <- mydata[1:4,]
four_rows %>% separate(Datetime, c('Date', 'Time'), sep=" ")

Answer 1

如果需要自动更新原始对象，请使用magrittr复合运算符(%<>%)

library(magrittr)
four_rows %<>%
separate(Datetime, c('Date', 'Time'), sep=" ")

现在我们检查

four_rows

Answer 2

从2个不同的url上传2个csv文件到dynamodb表。我使用熊猫从url中获取所需的数据，并将2个数据框合并为df3。当我使用put_item更新数据库时，我遇到了一个问题。我试过将熊猫系列转换成字符串，但这似乎也不起作用。下面是lambda函数:

import csv
import pandas as pd
import io
import requests
import numpy as np
import boto3
from datetime import datetime
import json
from decimal import Decimal
def lambda_handler(event, context): 

url1 = "https://raw.githubusercontent.com/nytimes/covid-19-data/master/us.csv"
url2 = "https://raw.githubusercontent.com/datasets/covid-19/master/data/time-series-19-covid-combined.csv"

df1 = pd.read_csv(url1)
df1 = pd.DataFrame(df1)
df1 = df1.drop(0)
df2 = pd.read_csv(url2, delimiter=',')
df2 = pd.DataFrame(df2)
df2['Recovered'] = df2['Recovered'].fillna(0).astype(np.int64)
df2 = df2.loc[df2['Country/Region'] == 'US', 'Recovered']
df2 = df2.reset_index(drop=True)
df2.index = np.arange(1, len(df2) + 1)

df3 = df1.join(df2)
region = 'eu-west-2'

try:
dyndb = boto3.client('dynamodb', region_name=region)
firstrecord = True
for row in df1:
if firstrecord:
firstrecord = False
continue
cases = df3['cases']
date = df3['date']
deaths = df3['deaths']
Recovered = df3['Recovered']
response = dyndb.put_item(TableName='covidstatstable',
Item={
'cases': {'N': cases},
'date': {'S': date},
'deaths': {'N': deaths},
'Recovered': {'N': Recovered},
})
print('Put succeeded:')
except Exception as e:
print(str(e))

，这里是功能日志: