Getting row id of data

I have a large data set of over 22 lac rows. This data comprises of 251 zones in Washington and out of these zones I am interested in only 30 zones. I used groupsummary to get the frequency of occurance of the a specific zone.

groupsummary(data,"PickupZone")

Now I want to get the row id of a specific PickupZone, for that I require some help on how to get the row id of every occurance of Astoria.

Then I will use that row id to assign a new variable in table for the regions comprising of those zones.

[Stephen23]

lac = 1e5

https://en.wikipedia.org/wiki/Lakh

Answer 1

[KSSV]

Let T be your table. And you want to seperate Astoria from T into another table T1.

idx = strcmp(T.PickupZone,'Astoria') ;
T1 = T(idx,:) ; 

[Sarmed Wahab]

No it is not working. it returns

idx =

logical

0

T1 =

0×23 empty table

[Sarmed Wahab]

Thanks for the help, I have figured out how to get his done.

t3 = ismember(taxi_all.PickupZone, {'Alphabet City','Astoria'})

this returns 1 at the place of occurance of these values.

from there I can replace those 1's with the region name.

[Walter Roberson]

taxi_all.RegionName(idx)