Undefined function or variable using readtable and IF

Hi there,

Im not sure why I am getting the error "UNDEFINED FUNCTION OR VARIABLE LANE1" at the end of the code where I am trying to assemble a table. Its obviously not looking at my, if Lanes == n, and I am not sure why. Here is the full code:

clear all
clc

%Percentage of different types of vehicles on roads
PercentageOfCars = 0.85 ;
PercentageOfBuses = 0.05 ;
PercentageOfTrucks = 0.10 ;

%Meters converted into miles
CarLength = 5 * 0.00062137;
BusLength = 10 * 0.00062137;
TruckLength = 15 * 0.00062137;

%Grabbing all data from excel file
DataSet = readtable('HighwayInformation.xls');

%Assinging variables from excel sheet
Mph = DataSet.SpeedLimitInMph;
SectionLength = DataSet.LengthOfTheSection_miles_;
Lanes = DataSet.NumberOfLanes;
BrakingDistanceCars = DataSet.CarBrakingDistance_miles_;
BrakingDistanceBuses = DataSet.BusBrakingDistance_miles_;
BrakingDistanceTrucks = DataSet.TruckBrakingDistance_miles_;

TimeToCompleteLane = (SectionLength ./ Mph); %Time in hours to complete respective section
TotalLengthWithLanes = SectionLength .* Lanes ; %Total length of section in miles

NumberOfVehiclesThatCanFitInLane = floor(SectionLength ./ (((BrakingDistanceCars + CarLength) * PercentageOfCars) + ((BrakingDistanceBuses + BusLength) * PercentageOfBuses) + ((BrakingDistanceTrucks + TruckLength) * PercentageOfTrucks)));
 
format shortg
PhasesOfVehicles = (1)./(TimeToCompleteLane);
MFV = (PhasesOfVehicles .* NumberOfVehiclesThatCanFitInLane);

%Lane 1 is inside lane
if Lanes == 2
    Lane1 = MFV;
    Lane2 = MFV * 0.95;
    Lane3 = nan;
    Lane4 = nan;
    Lane5 = nan;
    Lane6 = nan;
elseif Lanes == 3
    Lane1 = MFV;
    Lane2 = MFV * 0.95;
    Lane3 = MFV * 0.90;
    Lane4 = nan;
    Lane5 = nan;
    Lane6 = nan;
elseif Lanes == 4
    Lane1 = MFV;
    Lane2 = MFV * 0.95;
    Lane3 = MFV * 0.90;
    Lane4 = MFV * 0.85;
    Lane5 = nan;
    Lane6 = nan;
elseif Lanes == 5
    Lane1 = MFV;
    Lane2 = MFV * 0.95;
    Lane3 = MFV * 0.90;
    Lane4 = MFV * 0.85;
    Lane5 = MFV * 0.80;
    Lane6 = nan;
elseif Lanes == 6
    Lane1 = MFV;
    Lane2 = MFV * 0.95;
    Lane3 = MFV * 0.90;
    Lane4 = MFV * 0.85;
    Lane5 = MFV * 0.80;
    Lane6 = MFV * 0.75;
end


T = table(SectionLength,Mph,Lanes,Lane1,Lane2,Lane3,Lane4,Lane5,Lane6)

The rest of the code is working fine.

Answer 1

[Adam Danz]

As the error message indicates, there is no variable (or function) named 'Lane1' which means "Lanes" does not equal 2,3,4,5, or 6. You could add a last "else" at the end of your conditionals to catch such errors.

else
    error('''Lanes'' variable has unexpected value: %.3f', Lanes)
end

Also, if you're using discrete values, consider using a switch case instead.

%Lane 1 is inside lane
switch Lanes
    case 2
        Lane1 = MFV; %etc...
    case 3
        Lane1 = MFV;
    case 4
        Lane1 = MFV;
    case 5
        Lane1 = MFV;
    case 6
        Lane1 = MFV;
    otherwise
        error()
end

[Daniel Pearson]

Lanes is definetly only a value between 2 and 6 as I can confirm it by just doing Table(Lanes) so no idea why it is is not working. Lanes is a 647x1 double supposedly.

[Adam Danz]

" Lanes is a 647x1 double supposedly".

The 'if' command operates on a scalar value, not a vector.

If you're testing whether ALL of the values are equal to 2,

if all(lanes==2)

If you're testing that ANY of the values equal 2,

if any(lanes==2)

If you're just interested in the first value of lanes,

if lanes(1)==2

[Walter Roberson]

And if you want to process multiple entries in Lanes then you should use logical indexing.