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Campion Loong

MathWorks

Last seen: 2 months ago |  Active since 2015

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Answered
Help extracting rows based on unique column 1 data
I would first put my data in a timetable. It is specifically built for time based data like yours. % Make some pretend data for...

2 years ago | 0

Answered
convert excel time to time in a matlab
Simply use 'InputFormat' to parse the excel timestamp, and 'Format' to display it in your format of choice % Made up data - yo...

2 years ago | 0

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Answered
Extract data in a table following a a range of date (years)
I would use timetable for this kind of operations. It is specifically built for time based workflows. % Mock data for time betw...

2 years ago | 0

Answered
Operator '-' is not supported for operands of type 'table'
If you are using table and addressing one variable at a time, dot subscripting (i.e. t.VarName(...) ) is often preferrable to br...

2 years ago | 0

Answered
how to concatenate two tables efficiently
"I am trying to read a huge amount of files, each file would have data stored in a atable in it" Have you tried using Datas...

2 years ago | 0

Answered
Extracting specific words from cells within a table column and moving them to new column
Good code indeed. This is almost the same code, but you could go deeper into string with missing handling in the Data Preprocess...

2 years ago | 1

Answered
Extract data from a table corresponding to specific time
Use timetable's logical or time-based subscripting to address your data with time expressively % Some clean up at import since ...

2 years ago | 0

Answered
Plotting high frequency EDF data from timetable
The stackedplot visualization for timetable is built for exactly this kind of use cases edfData = edfread('example.edf'); %...

2 years ago | 1

Answered
I have 2 columns in a matrix. 1st column has the dates. 2nd column has the values. How do I grab all values from 2nd column associated with its date from the 1st column??
This kind of tasks is what timetable is built for: % Using your small example tt = timetable(datetime(2018,4,[1;2;2;3;3;3]), [...

2 years ago | 0

Answered
How to add hours to the time data of one day
Alternatively, if you want to 'expand' every day into 24 hours as in your file, you could do this in two steps (starting with a ...

2 years ago | 1

Answered
search content in table
If you are always using the values of d as a 'key' to look up other table variables, I would use straightly use d as the table's...

3 years ago | 0

Answered
Is it possible to rename columns in a table?
Renaming table and timetable variables has become straightforward since R2020a: renamevars Rename variables in tabl...

3 years ago | 2

Answered
How to find the first date of each month in a datetime array?
Alternatively... % dateshift all dates to beginning of the month, and find the indices of the first unique entry [~,idx_first_...

3 years ago | 0

Answered
Access data from table and assign to variables
Picking up from @Ive J's example, but use 'Vehicle' as Row Labels to take advantage of native table indexing: t = table([50; ...

3 years ago | 1

Answered
How do I specify a variable from a table that uses words and not numerical values
I would use a categorical for trashTags. trash = readtable('Litterati_processed_data.csv'); trash.Tags = categorical(trash.Tag...

3 years ago | 0

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Answered
How to apply an 'AggregationFunction' with two variables in unstack ?
How about this? >> t_groupsum = groupsummary(t,'group','sum',{'var1','var2'}); >> t_groupsum.Properties.RowNames = t_groupsum....

4 years ago | 0

Answered
How to Select Specific Time Intervals Over a series of time steps
I second Ameer's logical indexing approach. On the other hand, if this is representative of your data format, you may consider k...

4 years ago | 1

Answered
speed up renamecats/categorical multiple columns
Hi Peng, It seems you have the Dictionary code book to boot, and you already know which sets of code go wtih which field/name i...

4 years ago | 0

Answered
Convert Table to double vector
Hi Ameer, If you have R2019a and newer, you can try using readmatrix to directly read the file as numeric: https://www.mathwor...

4 years ago | 1

Answered
Slow 2020a performance writing to a Table in a loop
Hi Charles, Thanks for bringing up this performance question. I assume from your code snippet the timing is done either in the ...

4 years ago | 1

Answered
Poor R2019b performance with tables
Hi all, Continuing our investment in performance, R2020a has been released with more indexing improvement in table, timetable, ...

4 years ago | 4

Answered
Poor R2019b performance with tables
Thank you all for keeping track of table performance. First of all, we regret that the performance improvement in assigning i...

5 years ago | 2

Answered
Match datetime within 3 seconds from two tables of different sizes
This is a good question! Basically, if I understand correctly, you want to extract rows from table_2 whose timestamp matches tha...

5 years ago | 3

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Answered
Use datatime data of one table to find (and write) the nearest datetime and corresponding value data in another table
Use timetable instead of table for timestamped data. You may use table2timetable to convert table to timetable; or use readtimet...

5 years ago | 2

Answered
How to rearrange categoricals to a specified sequence
The categories of your categorical array is sorted in alphabetical order. % 'c' is your categorical array >> categories(c) an...

5 years ago | 0

Answered
Find column with error and delete it
You can fine-tune how MATLAB imports your data using various Import Options (Create import options based on file content). First...

5 years ago | 0

Answered
sorting unique date by time.
As Steve suggested above, you should import the CSV into a timetable and unstack to get what you want. I'd also mention the dete...

5 years ago | 0

Answered
Reducing a cell array of tables to a single table
Hi Ingo, Glad you've found a solution. In case it maybe useful in your workflow, I'd like to mention the various Datastores a...

5 years ago | 0

Answered
How to interpret ButtonDownFcn event data for axis which limit is datetime?
As Walter suggested, pasting my <https://www.mathworks.com/matlabcentral/answers/357449-how-to-interpret-buttondownfcn-event-dat...

7 years ago | 4

| accepted

Answered
Problem with 'keeplimits' for dates on figure x-axis
Hi Luc, I see that you are utilizing the |datetime| datatype <http://blogs.mathworks.com/loren/2015/02/12/introduction-to-the...

9 years ago | 1

| accepted

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