Populating values in a vector based on function

Question

Hari krishnan 2018-10-15

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/424072-populating-values-in-a-vector-based-on-function

评论： dpb 2018-10-16

ants_entry_exit_goodnest_14.0164.xlsx

I have an excel file as attached. In the second column, i have the 'entry time' and third column have 'exit time'. In the 'exit time', there are few values missing. I am doing an functional operation, which takes the 'entry time' and 'exit time'. When i perform this, i am getting an error "Subscript indices must either be real positive integers or logicals", due to the presence of nan's. Any help to solve this will be appreciated.

    real_time_vec = str2double(changed_ts_to_seconds{1,2}(:,5));               %choose good nest data text file
    frame_rate_played_video = 8;
    colony_data = 'ants_entry_exit_goodnest_14.0164.xlsx';
    read_colony_observation_data_goodnest = xlsread(colony_data);
    time_data_observation = floor(read_colony_observation_data_goodnest(:,2:3)*60); 
    entry_times_to_nest = time_from_videos_to_second_convertor(time_data_observation,frame_rate_played_video,real_time_vec);

The function 'time_from_videos_to_second_convertor' is shown below

 function [real_time] = time_from_videos_to_second_convertor(time_data_observation,frame_rate_played_video,real_time_vec)
 for ii = 1:length(time_data_observation)
    frame_id = time_data_observation*frame_rate_played_video;
    real_time = real_time_vec(frame_id);
 end

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dpb 2018-10-15

So, what do you expect for a result when there is the missing value?

Hari krishnan 2018-10-15

I just want to keep nan

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Answer 1

dpb 2018-10-15

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/424072-populating-values-in-a-vector-based-on-function#answer_341473

编辑：dpb 2018-10-16

在 MATLAB Online 中打开

function [real_time] = time_from_videos_to_second_convertor(time_data_observation,frame_rate_played_video,real_time_vec)
 for ii = 1:length(time_data_observation)
    frame_id = time_data_observation*frame_rate_played_video;
    real_time = real_time_vec(frame_id);
 end

in loop on ii, time_data_observation is referring to the whole array, not just single element
is it guaranteed that time_data_observation*frame_rate_played_video is integer even if not NaN
real_time is overwritten every pass thru the loop.

If you can't fix the NaN from happening, probably the simplest fix to your current code would be

    real_time=nan(size(time_data_observation));     % initialize to NaN for unknown
    for ii = 1:length(time_data_observation)
      frame_id = time_data_observation(ii)*frame_rate_played_video;
      try                                              % trap index error on missing value
        real_time(ii) = real_time_vec(frame_id);       % we're ok
      catch                                            % on error do nothing, already initialized
      end