Multi tool use

Identifying if a datetime from one dataframe is within an hour after another dataframe

I have 2 dataframes, A and B:

A

abc|def|datetime |
1 |55 |2016-01-28 00:00:00 |
2 |53 |2016-01-28 00:30:00 |
3 |11 |2016-01-28 02:00:00 |


B

efg|hij|datetime |
4 |ch |2016-01-28 00:11:00 |
5 |jw |2016-01-28 11:30:00 |
6 |q1 |2016-01-28 07:00:00 |


I Want to add a true false column to the end of A if a value B is within an hour after. And also a column that shows a value B is within an hour before.

A output:

abc|def|datetime |After|Before|
1 |55 |2016-01-28 00:00:00 | 0 | 1 |
2 |53 |2016-01-28 00:30:00 | 1 | 0 |
3 |11 |2016-01-28 02:00:00 | 0 | 0 |


I have tried using `library(lubridate):

for(i in seq(nrow(B))){
for(j in seq(nrow(A))){
if(A$datetime[j] %in% seq(B$datetime[i],B$datetime[i] + hours(1))){
A$After[j] = 1
}
}
}


But i can't get it to work. Any help would be greatly appriciated.

Additional Information:

The dataframes do not line up, I am wanting to identify if there are any cases in B which are within an hour After or Before A. If this is the case then add 1 to the column. eg:

4 |ch |2016-01-28 00:11:00 | is after 1 |55 |2016-01-28 00:00:00 |

4 |ch |2016-01-28 00:11:00 |

1 |55 |2016-01-28 00:00:00 |

4 |ch |2016-01-28 00:11:00 | is before 2 |53 |2016-01-28 00:30:00 |

4 |ch |2016-01-28 00:11:00 |

2 |53 |2016-01-28 00:30:00 |

B is an event and I am wanting to identify that event in relation to A.

Error in seq.POSIXt(B$Datetime[i], B$Datetime[i] + : exactly two of 'to', 'by' and 'length.out' / 'along.with' must be specified

1 Answer
1

Edited question based on extra info. In this case it is slightly easier. You can use functions from lubridate to find our if a datetime falls between 2 dates. You need 2 functions for this. First creating an interval object and secondly using the %within% function to find out if a date falls in an interval.

%within%

In the code below I created 2 interval objects, Before and After. To check if each value of B falls in one of the intervals we need to run a loop.

library(lubridate)

after_interval <- as.interval(3600, A$datetime)
# flip interval to get lower date first in the interval
before_interval <- int_flip(as.interval(-3600, A$datetime))

for(i in seq_along(length(B$datetime))) {
After <- B$datetime[i] %within% after_interval
After = as.integer(After)
if(i == 1){
AfterLoop = After
} else {
AfterLoop = AfterLoop + After}

Before <- B$datetime[i] %within% before_interval
Before = as.integer(Before)
if(i == 1){
BeforeLoop = Before
} else {
BeforeLoop = BeforeLoop + Before}
}
A$After <- AfterLoop
A$Before <-BeforeLoop
A
abc def datetime After Before
1 1 55 2016-01-28 00:00:00 TRUE FALSE
2 2 53 2016-01-28 00:30:00 FALSE TRUE
3 3 11 2016-01-28 02:00:00 FALSE FALSE


sf

buffer = st_buffer(B[i], 500)

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