How to Compare datetimes with milisecs?

Hi, when i compare the i-value from each table it says they are not the same becauase one has milisecs and the other has not, how to delete the mili secs so when i do

u1200lab(1,1)==u1300processo(1,1)

it gives me a positive logical answer?

Because now it says it is not true

Answer 1

[Steven Lord]

Let's generate two sample datetime objects and set their Format to show just the times with fractional seconds.

N = datetime('now');
N.Format = 'hh:mm:ss.SSS'
X = N + seconds(10*randn);
X.Format = 'hh:mm:ss.SSS'

What's the difference between the two? Is it less than 5 seconds?

d = abs(X-N);
d.Format = 'mm:ss.SSS'
d < seconds(5)

Or you can convert the difference into a number of seconds and compare with the number 5.

sec = seconds(d)
sec < 5

If you want to round the datetime object you could use dateshift to shift to the 'start' or 'end' of the second or shift to the 'nearest' second.

dateshift(N, 'start', 'second')
dateshift(N, 'start', 'second', 'nearest')
dateshift(N, 'end', 'second')

[Tiago Dias]

yeah i have tried it and it works so far, D = 1, i will try on my table data too see if it works also thanks

B = datetime('now')
B.Format = 'hh:mm:ss.SSS'
C = datetime('now')
C.Format = 'hh:mm:ss.SSS'
C=dateshift(C, 'start', 'second')
B=dateshift(B, 'start', 'second')
D = isequal(B,C)

Answer 2

[Are Mjaavatten]

s = 30;  % The accuracy you desire (in seconds)
close_enough = abs(u1200lab(1,1)-u1300processo(1,1)) < 1/24/3600*s

[Tiago Dias]

doesnt work on tables, and both are tables when i load them

Answer 3

[Peter Perkins]

This has nothing to do with milliseconds, at least not if what you posted is what you are actually doing.

I don't know what you are seeing, but the two mat files you've attached each contain an 8x1 table, each of whose sole variable is an 8x1 datetime. These tables may be a step along a longer journey, but in general, there's no point in creating a table with one variable.

In any case, what I see is

>> u1200lab(1,1)==u1300processo(1,1)
Undefined operator '==' for input arguments of type 'table'.

and that's because you are wanting to compare the datetime values in the table but in fact you are trying to compare two 1x1 tables and there's no comparison operator for tables because they are containers. What you need to do is compare the datetime values. Here's one way:

>> u1200lab.DataColheita(1) == u1300processo.Data(1)
ans =
  logical
   1

[Tiago Dias]

thanks a lot that helps me! Just to be clear u1200lab.DataColheita(1) the number 1, it refers to the column?

[Walter Roberson]

In u1200lab.DataColheita(1) the .DataColheita tells it which column of the table to look in. The (1) is then the row number of that column.

[Tiago Dias]

ok, so that doesnt help me a lot, since i will have multiple columns. will try the other sugestions then