# Assigning group labels to data *hctsa* allows you to map time-series data into a unified feature space, a representation that is well suited to then applying machine learning methods to perform classification where the goal is to predict a class label assigned to each time series from features of its dynamics. Class labels can be assigned to time series in an *hctsa* dataset using the function `TS_LabelGroups`, which populates the `Group` column of the `TimeSeries` table as a categorical labeling of the data (the class labels the classifier will attempt to predict). These group labels are used by a range of analysis functions, including `TS_PlotLowDim`, `TS_TopFeatures`, and `TS_Classify`. The machinery of `TS_LabelGroups` assumes that the class labels you are interested in are contained in the `Keywords` column of the `TimeSeries` table (set up from your original [input file](/hctsa-manual/installing-and-using-hctsa/calculating/input_files.md) when `TS_Init` was run). ## Labeling ### Manual labeling If you want to label according to a specific set of keywords, you can do this by specifying the keywords that define the unique groups. The example below assigns labels to two groups of time series in the `HCTSA.mat` (specifying the shorthand `'raw'` for this default, un-normalized data), corresponding to those labeled as `'parkinsons'` and those labeled as `'healthy'`: ``` TS_LabelGroups('raw',{'parkinsons','healthy'}); ``` Note that any time series that are not labeling by either `'parkinsons'` nor `'healthy'` are left unlabeled. ### Automatic labeling If every time series has a single keyword that uniquely labels it, `TS_LabelGroups` can automatically detect this by running `TS_LabelGroups('raw',{});`. ### Complex labeling More complex labeling (e.g., using custom combinations of keywords) is not implemented in `TS_LabelGroups`, but can be achieved by writing a script that does logical operations on calls to `TS_LabelGroups` and saves back to the `TimeSeries.Group` column. Here is [an example](https://github.com/benfulcher/hctsa_phenotypingFly/blob/master/labelCombination.m) of combining two labels (male/female and day/night) on fly movement data. ## Working with labels By default, the group labels are saved back to the data file (in this example, `HCTSA.mat`). Group labels can be reassigned at any time by re-running the `TS_LabelGroups` function, and can be cleared by running, e.g., `TS_LabelGroups('raw','clear')`. Assigned labels are used by the analysis, plotting, and classification functions of *hctsa*. *Note*: If you assign a labeling to a given dataset (e.g., `HCTSA.mat`), then this labeling will remain with the normalized data (e.g., after running `TS_Normalize`). --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://time-series-features.gitbook.io/hctsa-manual/installing-and-using-hctsa/analyzing_visualizing/grouping.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.