```{r, env, eval=TRUE, echo=FALSE, warning=FALSE, message=FALSE} library(knitcitations) cite_options(hyperlink = FALSE, style = "markdown") library(bibtex) extbib <- read.bib("pRolocGUI.bib") ```

pRolocGUI: Interactive visualisation of organelle (spatial) proteomics data

#### Thomas Naake and Laurent Gatto* #### *Computational Proteomics Unit, University of Cambridge ### Foreword This vignette describes the implemented functionality in the `pRolocGUI` package. The package is based on the `MSnSet` class definitions of `MSnbase` [`r citep(extbib["GattoLilley2012"])`](#references) and on the functions defined in the package `pRoloc` [`r citep(list(extbib["Breckels2013"], extbib["Gatto2014"]))`](#references). `pRolocGUI` is intended for the visualisation and analysis of proteomics data, especially for the analyses of LOPIT [`r citep(extbib["Dunkley2006"])`](#references) or PCP [`r citep(extbib["Foster2006"])`](#references) experiments. To achieve reactivity and interactivity, `pRolocGUI` relies on the [`shiny`](http://www.rstudio.com/shiny/) framework. The implemented application facilitates a higher degree of interactivity with the underlying spatial proteomics data: The distributed functions `pRolocVis` and `pRolocComp` offer interactive Principal Component Analysis (PCA) plots and protein profile plots, as well as exploration of quantitative and qualitative meta-data. Key features of `pRolocVis` and `pRolocComp` are the identification of features in plots, a 'reverse search' based on querying meta-data which allows for highlighting the features on plots and an import/export functionality by using the `FeaturesOfInterest`/`FoICollection` infrastructure distributed by the `MSnbase` package. Additionally, `pRolocComp` allows for comparison of two comparable `MSnSet` instances, e.g. this might be of great help for analyses of changes in protein localisation in different `MSnSet`s. We recommend some familiarity with the `MSnSet` class (see `?MSnSet` for details) and the `pRoloc` vignette (available with `vignette("pRoloc-tutorial")`). `pRolocGUI` is under active development; current functionality is evolving and new features will be added. This software is free and open-source. You are invited to contact Laurent Gatto (lg390@cam.ac.uk) or Thomas Naake (naake@stud.uni-heidelberg.de) in case you have any questions, suggestions or have found any bugs or typos. To reach a broader audience for more general questions about proteomics analyses using R consider of writing to the Bioconductor list. -------------------

1. Introduction

Currently, `pRolocGUI` distributes the `pRolocVis` and `pRolocComp`application. The function `pRolocVis` needs an object of class `MSnSet` or a list of `MSnSet` objects as an argument, while `pRolocComp` needs a list containing two instances of class `MSnSet`. To prepare the environment to run a `pRolocVis`/`pRolocComp` session, the `pRolocGUI` package and for demonstration purposes four example `MSnSet`s are loaded to the environment. The example data sets are available from the `pRolocdata` [`r citep(extbib["GattoPRolocdata"])`](#references) experiment package and are derived from experiments `andy2011` from [`r citet(extbib["Breckels2013"])`](#references), `tan2009r1` and `tan2009r2`, the first and second replicate from [`r citet(extbib["Tan2009"])`](#references) and `dunkley2006` from [`r citet(extbib["Dunkley2006"])`](#references). ```{r, echo = TRUE, message = FALSE, warning = FALSE} library("pRolocGUI") data(andy2011, package = "pRolocdata") data(tan2009r1, package = "pRolocdata") data(tan2009r2, package = "pRolocdata") data(dunkley2006, package = "pRolocdata") ``` `pRolocVis` needs an object of class `MSnSet` as an argument. We can launch the application with an `MSnSet` by assigning it to the argument `object`: ```{r, eval = FALSE, echo = TRUE} pRolocVis(object = andy2011) ``` Alternatively, to upload multiple objects of class `MSnSet`, `pRolocVis` accepts both lists with named and unnamed objects. This allows for analysis of multiple data sets without stopping the application from running. The names of objects of lists will appear in the drop-down menu in the **_data_** tab, while lists with unnamed objects will have a drop-down menu with automatically named entries as a consequence, i.e. object 1 ... object n, where n is the length of the list. ```{r, eval = FALSE, echo = TRUE} namedVis <- list(andy2011 = andy2011, tan2009r1 = tan2009r1, dunkley2006 = dunkley2006) unnamedVis <- list(andy2011, tan2009r1, dunkley2006) pRolocVis(object = namedVis) pRolocVis(object = unnamedVis) ``` `pRolocComp` requires a list of two `MSnSet`s which can be named or unnamed. ```{r, eval = FALSE, echo = TRUE} namedComp <- list(tan2009r1 = tan2009r1, tan2009r2 = tan2009r2) unnamedComp <- list(tan2009r1, tan2009r2) pRolocComp(object = namedComp) pRolocComp(object = unnamedComp) ``` N.B.! It is also possible to use a partly named list in `pRolocVis` and `pRolocComp`. Launching `pRolocVis` or `pRolocComp` will open a new tab in your default Internet browser. To stop the applications from running press `Esc` or `Ctrl-C` in the console (or use the "STOP" button when using RStudio) and close the browser tab, where `pRolocVis`/`pRolocComp` is running. -------------------

2. Tabs of pRolocVis and pRolocComp

To optimise ease of use the interfaces of `pRolocVis` and `pRolocComp` are subdivided in seven tabs: * PCA, * protein profiles, * quantitation, * feature meta-data, * sample meta-data and * search, * data. You browse through the tabs by simply clicking on them. Each tab selected will have a different kind of appearance while some (PCA, protein profiles, quantitation and feature meta-data) share a common feature in the sidebar, the *Display selection* widget (see section [3. Display selection widget](#display) for further details). In case you have a question and want to consult the vignette for a certain issue (e.g. regarding **_PCA_** tab or on how to use the *Display selection* widget) click on `?` which will open the vignette in a new browser tab in the corresponding section. In general, the tabs for `pRolocVis` and `pRolocComp` will look alike. The tab **_data_** however differs for the two applications. While in `pRolocVis` this tab allows for the selection of the used `MSnSet` and the upload of `.Rda` or `.Rdata` files, in `pRolocComp` there is the possibility to subset the used `MSnSet`s (in terms of using common, unique and common & unique features in the two `MSnSet`s used) as well as to submit features for selection. See [2.7. data](#tabspRolocGUIDataComp) for further details.

Fig. 1: Vignette of `pRolocVis` and `pRolocComp`

### 2.1. PCA The tab **_PCA_** is characterised by its main panel which shows a PCA plot for the selected `MSnSet` in the case of `pRolocVis` and two PCA plots for `pRolocVis`. The sidebar panel is divided into *Display selection* and *Plot*.

Fig. 2: Appearance of **_PCA_** tab for `pRolocVis` (`andy2011`)

For `pRolocComp` the plot whose appearance is going to altered has to be selected by selecting the appropriate [radio button](#RadioButtons) left of the name of the `MSnSet` instance in the sidebar panel. In addition, `pRolocComp` offers the possibility to mirror the PCA plot of the second object. By clicking on `x-axis` below **_mirror 2nd object_** features are mirrored along the x-axis, while clicking on `y-axis` mirrors along the y-axis. This may be important when you compare experiments whose PCA analysis have different signs.

Fig. 3: Radio buttons to select `MSnSet` in `pRolocComp`. Argument `object` is a named list with `MSnSet` instances `tan2009r1` and `tan2009r2`

The manipulation of the plots works the same way for `pRolocVis` and for `pRolocComp`: The *Display selection* widget is described [below](#display). The *Plot* compartment enables to adjust the appearance of the PCA plot in the main panel. We are able to colour features (proteins) in matters of common properties by changing the drop-down list **_colour_**. These properties are the `MSnSet`'s feature variables. For example if we upload the `andy2011` data set in `pRolocVis`, and select the colour `markers`, the features in the PCA plot will be coloured according to their organelle affiliation. As soon as we select another colour than `none`, two (or three) new items will be added to the *Plot* widget: (1) **_symbol type_**: By selecting one of the feature variables of the `MSnSet` in the drop-down list of **_symbol type_** the symbol type of the features in the plot will be changed. (2) **_legend_** and **_position of legend_**: By clicking on the check box to the left of **_legend_** a legend is added to the plot and by choosing one of the items in the drop-down list **_position of legend_** below its position will be changed. (3) **_point size_**: This drop-down list might appear when numeric feature variable have been identified. The default 1 allows for an unaltered display of the plot, while selecting other items in the list renders the features in the PCA plot according to their numerical value in the variable label (for example classification scores).

Fig. 4: Appearance of **_PCA_** tab (`andy2011`). `markers` used for colours, legend added.

By changing the drop-down lists of the items **_PC along x axis_** and **_PC along y axis_** the x-values and y-values, respectively, the plot will be rendered according to the new principal components. To zoom in and out drag and drop the little arrows of the slider of the items **_zoom x-axis_** and **_zoom y-axis_**. This may be of great help when you want to identify points in dense clusters. By clicking on **_Download Plot_** in the main panel below the PCA plot will open a dialog window with an interface on showing or saving the PCA plot as it is displayed in the main panel. ### 2.2. protein profiles For `pRolocVis` the tab **_protein profiles_** shows the protein profiles in the main panel (with an option of exporting the plot as it is shown in the main panel by clicking on the button **_Download Plot_**) - for `pRolocComp` it shows the plots for the two `MSnSet` instances (the corresponding plot(s) for the first element in the list will be displayed on the left, for the second element on the right). In the sidebar panel there is the *Display selection* widget and the *Plot* widget. Have a look on section [3. *Display selection* widget](#display) if you want to retrieve information about how to use the *Display selection* widget. The *Plot* widget helps to manipulate the plots shown in the main panel (in `pRolocComp` one has first to select the appropriate [radio button](#RadioButtons) next to the `MSnSet` instance in the sidebar panel). Let's assume we want to have a look upon the protein profiles for the proteins from which we know that they belong to the organelles Endoplasmic reticulum, the Golgi apparatus, Mitochondrion and the plasma membrane for the `andy2011` MSnSet. This is done in `pRolocVis`, but works in the same way in `pRolocComp`. We have four organelles to look at, so we select `4` (in `pRolocComp` there is either the possibility to select `1` or `2` plots per `MSnSet`) in the drop-down list **_number of plots to display_**. We will select the feature variable `markers` in the drop-down list **_feature(s) in_** and select `ER` (coding for Endoplasmic reticulum) in the drop-down list underneath (**_assigned to_**). To display the next plot we have to change the slider **_Selected plot_** to position 2. Accordingly to our question we will change the second drop-down list to `Golgi` (coding for Golgi apparatus). We proceed with the two remaining organelles as described before by changing firstly the slider to the next position and by changing the drop-down lists accordingly to the organelles we want to display. Please be aware that it is possible to "go" back to a plot to change its parameter.

Fig. 5: Appearance of **_protein profiles_** tab in `pRolocVis` showing protein profiles of organelles/compartments Endoplasmic reticulum, Golgi apparatus, Mitochondrion and plasma membrane of markers (`andy2011`)

### 2.3. quantitation The tab **_quantitation_** displays the quantitation data for the proteins as a data table. In the main panel you can change the number of proteins shown per page and search both for proteins (or for the quantitation data). Also, you may sort the proteins by name or the quantitation data by clicking on the arrows on the top of the data table. In the sidebar panel the *Display selection* widget is located as well as radio buttons to display all data or just selected features (see [3. *Display selection*](#display) for further details). In `pRolocComp` there is also another well panel to select the appropriate [radio button](#RadioButtons) next to the name of the `MSnSet` to show the respective quantitation data.

Fig. 6: Appearance of **_quantitation_** tab (`andy2011`) in `pRolocVis`. Features shown originate from selection made in the PCA and protein profiles plots

### 2.4. feature meta-data The tab **_feature meta-data_** displays the feature meta-data for the proteins as a data table. The layout of the tab is similar to the **_quantitation_** tab and allows for sorting and querying the feature meta-data of the selected `MSnSet`. The sidebar comprises the *Display selection* widget and radio buttons to show all or only selected features (see [3. *Display selection*](#display) for further details). In `pRolocComp` there is in addition a set of two [radio buttons](#RadioButtons) which allow to switch the `MSnSet` shown, thus, the feature meta-data will be rendered to the selected `MSnSet`.

Fig. 7: Appearance of **_feature meta-data_** tab (`andy2011`) in `pRolocVis`. Features shown originate from selection made in protein profiles plot

### 2.5. sample meta-data The tab **_sample meta-data_** displays the sample meta-data for the experiment, the name of the isotopes used for tagging and the associated fractions. In `pRolocComp` select the appropriate [radio button](#RadioButtons) next to the object name in sidebar panel to display the corresponding sample meta-data.

Fig. 8: Appearance of **_sample meta-data_** tab (`andy2011`) in `pRolocVis`

### 2.6. search The appearance and operation are identical for `pRolocVis` and `pRolocGUI`. `pRolocVis` and `pRolocComp` allow to use past search results to display in the PCA plot, protein profiles and in the tabs **_quantitation_** and **_feature meta-data_** (see [3. *Display selection*](#display) for further details if this is your intention). This ability requires the object `pRolocGUI_SearchResults` in the global environment which is of class `FeaturesOfInterest` or `FoICollection` (enter `?FeaturesOfInterest` in the console for further details). In case this objects exists it will automatically be loaded to `pRolocVis`/`pRolocComp` and its content is displayed in the tab **_search_**. Use the drop-down list in the main panel to browse through the different features of the `FoICollection`. To select features and display them in multiple tabs add them to the field in the multiple drow-down list. If no object called `pRolocGUI_SearchResults` exists in the global environment you still have the possibility to assign `FeaturesOfInterest` to an `FoICollection` which will be assigned to the global environment when exiting `pRolocVis`/`pRolocComp`. To save features of interest to the object internally you need to select features and add these to the `FoICollection` by entering an appropriate description in the text field (on the sidebar panel, which will be useful to trace back to the underlying features and does not exist yet in the `FoICollection`). Add the selected features to the object `pRolocGUI_SearchResults` in the global environment by clicking on **_Create new features of interest_**. You only have the possibility to add selected features to the `FoICollection` when you have entered an appropriate description, i.e. one that doesn't exist yet in the `FoICollection` and if you have selected `FeaturesOfInterest`, otherwise the button does not show up in the application. When exiting `pRolocVis`/`pRolocComp` the `FoICollection` will be assigned to the object `pRolocGUI_SearchResults` in the global environment. To create an example object `pRolocGUI_SearchResults` containing the first ten features of `tan2009r1` run the following commands in the console. Both traceable and non-traceable `FeaturesOfInterest`/`FoICollection` are usable by `pRolocVis`/`pRolocComp`. ```{r, eval = TRUE, echo = TRUE} data(tan2009r1, package = "pRolocdata") pRolocGUI_SearchResults <- FoICollection() newFeat <- FeaturesOfInterest(description = "test_01", fnames = featureNames(tan2009r1)[1:10], object = tan2009r1) pRolocGUI_SearchResults <- addFeaturesOfInterest(newFeat, pRolocGUI_SearchResults) ```

Fig. 9: Appearance of **_search_** tab (`andy2011`) in `pRolocVis`. Search result `pRolocVis_Test1` contains one feature of interest (PGAP1_Human)

### 2.7. data The tab **_data_** is the last tab for `pRolocVis` and `pRolocComp`.

Fig. 10: Appearance of **_data_** tab in `pRolocVis`

For `pRolocVis` the drop-down menu lists all the names of assigned `MSnSet` objects to the function. Depending if a named list - containing `MSnSet` instances - is uploaded or not these names will be used or automatic names will be created (object 1 ... object n, where n is the length of the list). In addition, the entry `upload` is listed at the bottom of the drop-down menu. Selecting `upload` allows to use a `MSnSet` available in a `.Rda` or `.Rdata` file after uploading it to the application. Clicking on **_Browse..._** will open a dialog window with which you can select a file containing a saved `MSnSet` and load it to `pRolocVis`. Make sure if you want to use a `MSnSet` from a `.Rda` or `.Rdata` file to select `upload` in the drop-down menu.

Fig. 11: File upload in `pRolocVis`

`pRolocVis` will print a message if there are any conflicts with the uploaded file. If so, either the assigned object itself or the first element in the list will be used instead of the uploaded `.Rda` or `.Rdata` file. When analysing multiple data sets in one `pRolocVis` session the selected features will be (irreversibly) deleted when changing from one `MSnSet` to the other! It is therefore highly recommended if this behaviour is not intended to save selected features by using the functionality to save features in a `FoICollection` first before changing the `MSnSet` (see [2.6. search](#tabspRolocVisSearch) for further details). For `pRolocComp` the main panel shows a summary matrix of common and unique feature names consisting of common and unique features for all feature names of the two `MSnSet` instances (row `all`) and for distinct subsets which are defined by the feature variable names. The feature variable names can be defined by choosing appropriately the drop-down menus **_marker object 1_** and **_marker object 2_** which are located in the section *Summary matrix* in the sidebar panel (enter `?FeatComp` to retrieve more information about the summary matrix). The matrix in the main panel will show only features for distinct subsets when both drop-down menus do not have `none` as their value, otherwise only the row `all` will be printed. Given `tan2009r1` and `tan2009r2` as input for `pRolocComp`, when selecting `markers` both for **_marker object 1_** and **_marker object 2_** the matrix will consist of six rows (`all`, `unknown`, `ER`, `mitochondrion`, `Golgi`, `PM`). The table can be interpreted as follows: For the row `all` we have `545` common features, i.e. there are `545` features in the two `MSnSet`s which have identical feature names. In `tan2009r1` however, there are `343` feature names which do not exist in `tan2009r1` and `326` feature names are unique for `tan2009r2`. For `markers` the matrix tells us that features were assigned to 4 organelles on an experimental evidence (`ER`, `mitochondrion`, `Golgi`, `PM`) for `833` features in both `MSnSet`s the affiliation to a certain organelle is `unknown`. In total `20` features are assigned to `ER` for `tan2009r1`, therefrom `16` features are also present in `tan2009r2`, however, `4` are unique to `tan2009r1`. The interpretation of the other rows can be deduced in the same way. Features can be selected and [displayed](#display) in the other tabs, e.g. highlighted on the PCA plot. The selection is conducted in the section *Selection*. It is made by selecting a marker via the drop-down menu **_select marker_** and the radio buttons underneath. The selected row, column and the number of features which is comprised in these categories will be displayed in bold in the summary matrix. By pressing **_Submit selection_** the features will be saved internally, thus, available for displaying/use in other tabs. The button **_Submit selection_** will be only shown when the features are not already stored internally). If the features are selected there will be the button **_Undo selection_** which allows to remove features from the internal selection.

Fig. 12: Appearance of **_data_** tab in `pRolocComp`. The row `ER` and column `unique1` which comprises `4` features are selected

The tab **_Data_** in `pRolocComp`also allows for subsetting the data sets by choosing accordingly `common`, `unique` and `common & unique` (default) in the section *Submit MSnSets*. The subset is made on the basis of the feature names of the two `MSnSet` instances. Selecting `common` will use only features which occur in both `MSnSet`s, `unique` will use no common features and `common & unique` will use all feature names for each `MSnSet`. -------------------

3. Display selection widget

The *Display selection* widget is probably the most important implementation in `pRolocVis`/`pRolocComp` and allows for identifying features. You can do this by selecting points in the PCA plot, clicking on features in the tab **_protein profiles_**, using past searches and/or querying for features in the `MSnSet` data. In `pRolocComp`there is in addition the possibility to retrieve features from the summary matrix in the tab `data`. There are four (`pRolocVis`) or five (`pRolocComp`) check boxes in the *Display selection* widget which represent the before mentioned ways of searching features in the `MSnSet`. To activate the search for one specific method click on the check box left of its description. It is also possible to select more than one at a time which allows for greater flexibility with regard to information retrieval. To irreversibly reset the selection press **_Clear features_** (only shown when features are selected). ### 3.1. PCA If you decide to identify proteins in the PCA plot, change to the tab **_PCA_** and start clicking on features in the PCA plot (tip: the zoom function may be of great expedient). When hovering over the PCA plot the feature meta-data of the nearest feature will be displayed below the plot. The check box will be checked when you start clicking in the PCA plot. As soon as you have clicked on a feature it will be marked with a black circle around it (or a blueish if `colour` is set to `none`). If you have selected a feature by accident or want to deselect it, just click again on the feature and it will be deselected. Selecting features works also in `pRolocComp`: just click on features in one of the PCA plots will also highlight the same feature in the other plot if it is present. If you want to analyse features which are only common in the two `MSnSet` instances, go to tab **_Data_** and select `common` in the radio button list **_Features used_**.

Fig. 13: Display of selected features in PCA plot (`andy2011`) for `pRolocVis`. The features selected originate from selection in the PCA plot

There are two possibilities to deselect all selected features: If you decide to remove all your features click on **_Clear features_** (the button will only show up if features were already selected). Please keep in mind that this step once carried out is irreversible and will delete features selected in `protein profiles`, (`summary matrix`) and `query` as well. Besides that you are also able to simply blind out the selected features by deselecting the check box left of PCA in the *Display selection* widget. Internally, the features are still stored, i.e. by clicking again on the check box you will see the selections again. Clicking on new proteins in the PCA plot will not check the check box again, so you have to do this manually. The features selected are shared between the different tabs. Click on the tabs **_quantitation_** and **_feature meta-data_** to have a look upon information about the selected features. For the case where you see all features in the data table change the radio buttons settings from **_all_** to **_selected_** at the lowermost widget in the sidebar. Here again, you can compose the features from different sources (PCA, protein profiles, saved searches and the text-based query search). If you display protein profiles in the tab **_protein profiles_** selected features will be displayed by black lines on all plots drawn.

Fig. 14: Display of selected features in protein profiles plot for `pRolocVis`. The features selected originate from selection in PCA plot (`andy2011`)

### 3.2. protein profiles In principle the search for features in protein profiles is in accordance with the search in the PCA plot. Though, bear in mind that you are only able to select features when `1` is selected in the drop-down list **_number of plots to display_**. Hovering over the plot will display the feature meta-data of the nearest protein below the plot. Clicking on (or near) the points in the plot will select, clicking another time will deselect features. The features will only be shown when the check box left of **_protein profiles_** is activated. Note, that you can only select or deselect features whose protein profiles are displayed in a transparent manner on the plot. For `pRolocComp` selecting features works in the same way: click on features in one of the protein profile plots (make sure that `1` is selected in the drop-down list **_number of plots to display_**), thus highlighting the same feature in the other plot if the same feature name is present. If you want to analyse features which are only common in the two `MSnSet` instances, go to tab **_data_** and select `common` in the radio button list **_Features used_**.

Fig. 15: Display of selected features in protein profiles plot for `pRolocVis`. The features selected originate from selection in protein profiles plot (`andy2011`)

### 3.3. saved searches Clicking on the check box to the left of **_saved searches_** will load the selected features of the class `FeaturesOfInterest`. These will be displayed in the PCA plot, in the plots for protein profiles (depending on the displayed features) and will be available in the tabs **_quantitation_** and **_feature meta-data_** for information retrieval. Add `FeaturesOfInterest` by clicking on the respective features in the tab **_search_** in the multiple drop-down list; thus accordingly altering the selected features in the *Display selection* widget context. Each `FeaturesOfInterest`instance will be highlighted in a different colour to distinguish easily between them. In `pRolocVis`/`pRolocComp` there is no functionality implemented to remove features from the object `pRolocGUI_SearchResults` in the global environment. The authors decided that it is not the task of a GUI to fulfil the requirements of this kind of data manipulation in a GUI, hence, the execution of removing features of interests belongs to the field of the users responsibility. ### 3.4. summary matrix (`pRolocComp` only) In `pRolocComp` another way of selecting and displaying features is possible via the tab **_data_**. Features can be selected and internally stored by selecting "all"/a marker via the drop-down menu **_select marker_** - this will change the selected row - and one of the radio buttons underneath - this will change the column. By pressing the **_Submit selection_** button the features comprised in these categories will be stored internally. The button will be only shown when the features are not already stored internally and can be displayed/used in the other tabs. The selected row, column and the number of features which is comprised in these categories will be displayed in bold in the summary matrix. If features were submitted another button will be present which allows to remove the features from the internal selection, the **_Undo selection_** button. When submitting features from the columns `unique1` and `unique2`, the feature names will only be saved internally to the correspondent `MSnSet` and displayed there accordingly. This is done because it is possible that the same feature name exists in the other `MSnSet` but is not assigned to the `organelle`. As an example, for the two `MSnSet`instances `tan2009r1` and `tan2009r2` a selection of `markers` and `markers` as **_marker object 1_** and **_marker object 2_**, when selecting `mitochondrion` in **_select marker_** and the radio button next to `common` will be equivalent to and will contain the following features ```{r, eval = TRUE, echo = TRUE} data(tan2009r1, package = "pRolocdata") data(tan2009r2, package = "pRolocdata") featcomp <- compfnames(x = tan2009r1, y = tan2009r2, fcol1 = "markers", fcol2 = "markers", verbose = FALSE) ## the fourth element in the list bears information about features which are assigned to ## "mitochondrion" in "markers", we can access all common features for tan2009r1 and tan2009r2 by feat <- slot(featcomp[[4]], "common") feat ``` The selection means that for the marker object `markers` there are nine common features comprised in the two data sets which are assigned to `Mitochondrion` in the column `markers` of the feature meta-data. Going to the tab **_feature meta-data_** will list these features as well as meta-data. The stored features will only displayed when the check box next to `summary matrix` in the *Display selection*(#display) widget is selected. ### 3.5. query feature-meta data The *Display selection* widget offers the opportunity to query the feature meta-data of the `MSnSet` for levels. The drop-down list consists of the item `protein`, which will by definition the feature names and depending on the data accession number, protein ID, protein description, assigned markers (varying on the underlying `MSnSet`). For demonstration purposes we will use `pRolocVis` to select and display features by using the `query` functionality. Keep in mind, to adjust the selection of the [radio buttons](#RadioButtons) next to the appropriate `MSnSet` when using `pRolocComp`: Accordingly to the selected `MSnSet` the list of feature variables is rendered. Let's assume we want to look at `andy2011` which was derived from experiments of Breckels et al. (2013) for all proteins which are assigned by experimental evidence to the organelle `plasma membrane`. We ensure ourselves that `andy2011` is selected in the tab **_data_** and change to a tab where the *Display selection* widget is loaded. We select `marker` in the upper drop-down list (for we are looking for organelles assigned to marker proteins). In the next drop-down list below we select `PM` which codes for `plasma membrane`. Next, we click on **_Submit selection_**, which will highlight all features which are assigned to `PM` for the variable name `marker` (the button only appears in the application when the corresponding proteins do not exist in the selection). To remove the selected features from the internal assignment we have to either reset the search by clicking on **_Clear features_** or click on **_Undo selection_**. The latter will only remove the current selection of features, while the former will clear all features (also these of **_PCA_**, **_protein profiles_** (and **_data_**). Of course, we can also add other features: If we want to add all features which are assigned to the Golgi apparatus we simply select `Golgi` in the lower drop-down list and click on **_Submit selection_** to save internally the selected features. It is relatively easy to find levels when the drop-down list for these levels. But how should we proceed when we want to look for a special protein, e.g. ACADV? The drop-down list for the variable name `protein` is very long and it is time consuming to scroll through the whole list and look for our protein of interest. Therefore, we can just enter ACADV in the text input field **_Search for_** in between the two drop-down lists and we will get the protein of interest (we are also able to query for protein names which have the string `AC` in their name which will limit the drop-down list to all proteins which have this specific string). By clicking on **_Submit selection_** we save internally the selected feature(s).

Fig. 16: Query for proteins in `pRolocVis` which contain the string "AC". This narrows the features in the drop-down list accordingly (`andy2011`)

-------------------

4. References

```{r, results="asis", message=FALSE, echo=FALSE} bibliography() ```