Extract data in a table following a a range of date (years)

Good day to all,

I have a thre column table, after some manipulation I get the years from dd/mm/yyyy to only yyyy. Now I have to filter this table using year as filter variable.

Date starts at 1900 and ends at 2050, the interval i need is from 1956 to 2020.

I have created a logical vector using

yearFiltered=newDataFiltered.yearFiltered(newDataFiltered.yearFiltered>1955 & newDataFiltered.yearFiltered<2021)

then i've tried to index the main data set using the variable above following A(B)=[]

the outcome of the syntax is that "when deleting elements from a table variable using indexed assignments, the number of the rows must not change. Specify the first subscript as a colon (:) and exactly one other subscript that is not a colon"

infact the rows number will be reduced.

Answer 1

[Cris LaPierre]

Your table has 3 columns. Your deletion code must delete all 3 columns. You specify 'all columns' by adding a colon in the 2nd position.

A(B,:)=[]

% ^^ add colun to second index position

[alejandro paradiso]

thank you cris,

infact I want also erase the rows from the other columns

'Monday' '08:07:30 PM' 1900

'Wednesday' '02:50:12 PM' 1910

'Friday' '09:11:48 AM' 1920

'Sunday' '02:02:06 AM' 1930

'Monday' '04:36:36 PM' 1940

'Wednesday' '04:38:36 AM' 1950

'Thursday' '02:21:54 PM' 1900

from the data above, lets say i'm interested (columns & rows) in the years from 1920 to 1940, so in the end i will have a table 3x3

[Cris LaPierre]

Use a logical expression to identify the rows within the range of years you want, and then either extract those rows, all columns to a new variable or delete all other rows, all columns by taking the NOT of your logical expression.

a = ([1:3;4:6])'

a = 3×2

1 4 2 5 3 6

idx = a(:,1)==2

idx = 3×1 logical array
   0
   1
   0

% Extract row
b = a(idx,:)

b = 1×2

2 5

% delete other rows
a(~idx,:)=[]

a = 1×2

2 5

Answer 2

[Campion Loong]

I would use timetable for this kind of operations. It is specifically built for time based workflows.

% Mock data for time between 1900 - 2050
dt = datetime(1900,1,1)+calmonths(1:12*150)';
data = (1:length(dt))';

% timetable automatically picks up the one datetime variable as your time vector
tt = timetable(dt, data)

tt = 1800×1 timetable
        dt         data
    ___________    ____

    01-Feb-1900      1 
    01-Mar-1900      2 
    01-Apr-1900      3 
    01-May-1900      4 
    01-Jun-1900      5 
    01-Jul-1900      6 
    01-Aug-1900      7 
    01-Sep-1900      8 
    01-Oct-1900      9 
    01-Nov-1900     10 
    01-Dec-1900     11 
    01-Jan-1901     12 
    01-Feb-1901     13 
    01-Mar-1901     14 
    01-Apr-1901     15 
    01-May-1901     16 

Then use timerange to select data you are interested in

% Make a timerange subscript for 1956 - 2020
tr = timerange(datetime(1956,1,1),datetime(2020,12,31))

tr = 
	timetable timerange subscript:

		Select timetable rows with times in the half-open interval:
		[01-Jan-1956 00:00:00, 31-Dec-2020 00:00:00)

	See Select Times in Timetable.

% Get all the rows within this range of time
tt(tr, :)

ans = 780×1 timetable
        dt         data
    ___________    ____

    01-Jan-1956    672 
    01-Feb-1956    673 
    01-Mar-1956    674 
    01-Apr-1956    675 
    01-May-1956    676 
    01-Jun-1956    677 
    01-Jul-1956    678 
    01-Aug-1956    679 
    01-Sep-1956    680 
    01-Oct-1956    681 
    01-Nov-1956    682 
    01-Dec-1956    683 
    01-Jan-1957    684 
    01-Feb-1957    685 
    01-Mar-1957    686 
    01-Apr-1957    687 

[alejandro paradiso]

interesting suggestion, thank you Campion

[Campion Loong]

You're welcome.