Filtering or matching by exact time-CodePudding

When I try and filter a df by an exact time, not between two different times it produces a NA. I am trying to create a variable in df1 that is based on information in df2.

Here is my data

dput(df2)
structure(list(Time = structure(c(1647531450.72, 1647531451.757, 
1647531452.794, 1647531453.83, 1647531454.867, 1647531455.818, 
1647531456.854, 1647531457.891, 1647531458.928, 1647531459.878, 
1647531460.915, 1647531461.952, 1647531462.902, 1647531463.939, 
1647531464.976, 1647531466.013, 1647531467.05, 1647531468, 1647531469.037, 
1647531470.074, 1647531471.11, 1647531472.147, 1647531473.098, 
1647531474.134, 1647531475.171, 1647531476.208, 1647531477.245, 
1647531478.195, 1647531479.232, 1647531480.269, 1647531481.306, 
1647531482.342, 1647531483.293, 1647531484.33, 1647531485.366, 
1647531486.317, 1647531487.354, 1647531488.39, 1647531489.427, 
1647531490.378, 1647531491.414, 1647531492.451, 1647531493.488, 
1647531494.438, 1647531495.475, 1647531496.512, 1647531497.549, 
1647531498.586, 1647531499.536, 1647531500.573, 1647531501.61, 
1647531502.56, 1647531503.597, 1647531504.634, 1647531505.67, 
1647531506.621, 1647531507.658, 1647531508.694, 1647531509.645
), tzone = "", class = c("POSIXct", "POSIXt")), LAT = c(17.8799454, 
17.8799729, 17.8799952, 17.8800159, 17.8800416, 17.8800708, 17.8801, 
17.8801292, 17.8801567, 17.8801877, 17.8802237, 17.8802581, 17.8802873, 
17.8803148, 17.8803474, 17.8803818, 17.8804161, 17.8804471, 17.8804763, 
17.8805089, 17.8805381, 17.880569, 17.8806034, 17.880636, 17.8806721, 
17.8807048, 17.8807374, 17.8808061, 17.8808405, 17.8808783, 17.8808783, 
17.8809556, 17.8809968, 17.8810346, 17.8810724, 17.8810724, 17.8811497, 
17.8811892, 17.8812288, 17.88127, 17.8813112, 17.8813524, 17.8813954, 
17.8814383, 17.8814813, 17.8815208, 17.8815603, 17.8815964, 17.8816359, 
17.8816737, 17.8817132, 17.8817562, 17.8817974, 17.8818438, 17.8818885, 
17.8819314, 17.8819726, 17.8820104, 17.88205), LON = c(-62.8613544, 
-62.8613338, -62.8613063, -62.8612857, -62.861265, -62.8612513, 
-62.8612307, -62.8612101, -62.8611894, -62.8611757, -62.8611688, 
-62.8611482, -62.8611276, -62.8611139, -62.8611001, -62.8610795, 
-62.8610658, -62.861052, -62.8610314, -62.8610176, -62.860997, 
-62.8609833, -62.8609627, -62.8609489, -62.8609352, -62.8609214, 
-62.8609008, -62.8608733, -62.8608665, -62.8608596, -62.8608596, 
-62.8608459, -62.860839, -62.8608321, -62.8608252, -62.8608252, 
-62.8608115, -62.8608115, -62.8608115, -62.8608115, -62.8608115, 
-62.8608115, -62.8608115, -62.8608115, -62.8608115, -62.8608046, 
-62.8607977, -62.8607909, -62.860784, -62.8607771, -62.8607771, 
-62.8607771, -62.8607771, -62.8607771, -62.8607771, -62.8607703, 
-62.8607634, -62.8607496, -62.8607428)), class = "data.frame", row.names = c(NA, 
-59L))

and the df containing the information I want to filter by

dput(df1)
structure(list(date = structure(19068, class = "Date"), RaceStartTime = structure(1647531480, tzone = "", class = c("POSIXct", 
"POSIXt"))), class = "data.frame", row.names = "event.2")

I have tried the following

df1$lon <- df2$LON[match(df1$RaceStartTime, df2$Time)]

I have also tried

df1$lon <- df2%>%
  filter(Time == df1$RaceStartTime)

Both of these produce empty rows, can some one point out the obvious mistake?!

EDIT: The structure appears the same

str(df1$RaceStartTime)
 POSIXct[1:1], format: "2022-03-17 15:38:00"

str(df2$Time)
 POSIXct[1:59], format: "2022-03-17 15:37:30"

Thanks

CodePudding user response：

POSIXct format by default only prints whole seconds, but its underlying representation can contain fractional seconds (as your data in df2 does).

You can remove the fractional seconds by doing:

df2$Time <- lubridate::floor_date(df2$Time)

So now you get:

df2%>%
     filter(Time == df1$RaceStartTime)
#>                  Time      LAT       LON
#> 1 2022-03-17 15:38:00 17.88088 -62.86086