Converting to array index

Okay so I am given a csv file with the a month, year and water level.

The first entry is January 1940 with say 50 water level and the last is 2015 august with 70 water level.

Now we are required to get a user to enter two different months and years and plot the water level between those two respective points. i.e for example between January 2000 and December 2000.

Now I imported all the data as follows:

Water = importdata('melbournewaterlevels.csv');
StrMonth = Water.textdata(2:end,2);
StrYear=Water.textdata(2:end,1);
WaterLevel = Water.data;
StrYear(1 : end, 1 : end);

Now prompting the user to enter there choice:

m1=input(' Please input Month 1: ');
y1=input(' Please input Year 1: ');
m2=input(' Please input Month 2: ');
y2=input(' Please input Year 2: ');

How can I get that for example to convert it into an index?

Answer 1

[Andrei Bobrov]

Please attach small part of the your file: melbournewaterlevels.csv.

date1 = [StrYear StrMonth];
level1 = Water.data;
ym1=input(' Please input first Year and Month as [Year, Month]: ');
ym2=input(' Please input last  Year and Month as [Year, Month]: ');

l1 = datenum([ym1,1;ym2,1]);
d1 = datenum([date1,ones(size(date1,1),1)]);
out = WaterLevel(l1(1)>=d1 & l1(2)<=d1);

or

l1 = find(cumsum(ismember(date1, [ym1;ym2],'rows'))==1);
out = WaterLevel([l1;l1(end)+1]);

EDIT (after attaching of file)

Water = importdata('melbournewaterlevels.csv');
x = strcat(Water.textdata(2:end,1),Water.textdata(2:end,2));
d1 = datenum(x,'yyyymmm');

ym1=input(' Please input first Year and Month as [Year, Month]: ');
ym2=input(' Please input last  Year and Month as [Year, Month]: ');

l1 = datenum([ym1,1;ym2,1]);
out = Water.data(l1(1)>=d1 & l1(2)<=d1);

or

[y,m] = datevec(d1);
l1 = find(cumsum(ismember([y,m], [ym1;ym2],'rows'))==1);
out = Water.data([l1;l1(end)+1]);

[Walter Roberson]

Please attach a part of your file melbournewaterlevels.csv

[Steven]

Is this of use.