element_text. m^-2)" The line break should be after "mobile" and the "per square m" should be in superscript. So I don't think expand is actually the way to go about this, rather expand_limits . GGPlot2 Essentials for Great Data Visualization in R. There are two ways of transforming an axis. frame(x=1:10, y=c(11:17,5:3)) ggplot(dat, aes(x,y)) +. How to center align a wrapped axis title in ggplot2? Oct 14, 2019 · Introduce explicit line break in ggplot2 on the Y-axis (boxplot) 1. 6, 0. Center align ggplot title when title is placed within the plot area. # Load ggplot2 library (ggplot2) # Very basic chart basic <- ggplot ( mtcars , aes ( x= mpg, y= wt Sep 27, 2016 · r; ggplot2; line-breaks; or ask your own question. In the simplest case they map linearly from the In this article, I’ll explain how to increase and decrease the text font sizes of ggplot2 plots in R. Will only have an effect if breaks = waiver(). How can I control the x-axis breaks and labels on a ggplot facet grid so that the (time series) x-axis is identical for each facet, shows only at the bottom of the panel and is in the form of months formatted 1, 2, 3 etc or as 'Jan','Feb','Mar'? Code follows: Alternatively, it also provides guide_axis(n. The following code shows how to create a scatterplot in ggplot2 and use scale_x_continuous () with the breaks argument to specify custom axis breaks of 5, 15 and 25: #create scatterplot with custom x-axis breaks. Modify a single plot's theme using theme(); see theme_update() if you want modify the active theme, to affect all subsequent plots. scale_x_discrete() doesn't seem to do anything useful in this situation. # h Oct 15, 2020 · I would like to automatically wrap my labels in ggplot2, i. All labels (including the y-axis label) are printed upright, improving readability but still squeezing the plot area (but to a lesser extent as the chart is in landscape format): p + coord_flip() Vertical bar chart with labels wrapped. However, we need to tweak a bit the position and make enough space for the custom title. The easiest and quickest and nicest way to fix these long labels, though, is to use the label_wrap() function from the scales package. library (tidyverse) theme_set (theme_bw (18)) Jun 19, 2019 · 10. Mar 12, 2019 · Here is fully reproducible example of the original poster's problem where a log-scaled plot only displays one break value on the x-axis. Apr 2, 2012 · There are several ways we can deal with this. Change axis breaks in ggplot Building on a-s-k's answer I put this in a more flexible form using glue templates and a discrete scale. Aug 2, 2016 · A character vector giving labels (must be same length as breaks) A function that takes the breaks as input and returns labels as output. So for your two lines example, we could call atop() two times, which forces 3 lines, but we set the first line empty so that the next atop plots the text smaller and also the a smaller gap between the lines. ggplot already has the data, so it seems like it can figure out the min/max. May 5, 2019 · IMHO, tick marks and axis labels should be sufficient to indicate the range of data on display. Assuming the former, you can use scale_y_continuous() to define your own breaks. I demonstrate three possible solutions below. breaks' in 'scale_x_continuous'. To make the labels appear I needed to set breaks first. I've also tried playing with the plot margins to no avail. I used scale_x_continuous(breaks=seq(1,12,1),labels=my_labels). fr Finally, there is also the axis. 1)) Problem with the option1 is that it breaks in every 0. how to break ggplot code into multiple lines in rstudio. text. Example 3: Add Subtitle with Custom Font The following code shows how to use the theme() function in ggplot2 to add a subtitle with a custom font size, style, and color: Jan 5, 2019 · ggplot2. First, we will use stringr’s str_wrap () function and then use scales’s label_wrap () function to wrap the labels by specifying a width. I want to use 'n. 5, 12. I have created this scatterplot showing relationship between age and proprioception of both forelimbs and hindlimbs. Jun 21, 2020 · Suppose I have this data frame. 3) Example 2: Modify Minor Grid Lines on Y-Axis of ggplot2 Plot. A character to cut the axis line back to the last breaks. You do it by explicitly specifying minor_breaks() in the scale_x_continuous. e. The algorithm may choose a slightly different number to ensure nice break labels. I want to customize the gap (breaks) in the y axis of the plot. 6. So if there are 12 data points there would be 12 ticks / labels. minor = element_line(colour = "white", size = 0. Example: Draw ggplot2 Plot with Additional Axis Tick Marks without Labels. The function scale_x_continuous () and scale_y_continuous () can be used for ggplot axis breaks settings. geom_bar ( stat = "identity") ggp # Print ggplot2 barplot. Rotate axis text labels. The individual theme elements are: line all line elements (‘element_line’) rect all rectangluarelements (‘element_rect’) text all textelements (‘element_text’) title all Mar 6, 2014 · To map line into the legend you should map the variable to aesthetic. A custom lineplot with annotations to explore the evolution of the Big Mac Index with ggplot2, ggrepel and ggtext. May 6, 2019 · 3. geom_point() +. An integer guiding the number of major breaks. Nov 29, 2017 · The line break does not show up. Jan 27, 2021 · Since quarters is of type POSIXct you can use scale_x_datetime and specify the format and breaks in which you want to show the x-axis value. 5. Sep 30, 2016 · Date axis labels in ggplot2 is one day behind My data ranges from 2016-09-01 to 2016-09-30, but labels in plots say 2016-08-31 is the first day of data. This function adds geoms to a plot, but unlike a typical geom function, the properties of the geoms are not mapped from variables of a data frame, but are instead passed in as vectors. The tutorial consists of these content blocks: Example Data; Example 1: Change Font Size of All Text Elements; Example 2: Change Font Size of Axis Text; Example 3: Change Font Size of Axis Titles; Example 4: Change Font Size of Main Title Aug 23, 2021 · Example 2: Specify Y-Axis Ticks in ggplot2 Plot. name: x or y axis labels; breaks: control the breaks in the guide (axis ticks, grid lines, …). 1), and the symbol displayed in a legend varies based on the geom used in the layer (Section 14. name: x or y axis labels; breaks: to control the breaks in the guide (axis ticks, grid lines, …). The most common continuous position scales are the default scale_x_continuous() and scale_y_continuous() functions. However, things can get tricky if you want a lot of control over all plot elements. 0. I've tried This post shows how to control the grid lines of a ggplot2 graph in the R programming language. Just noting that here in case it helps someone else. The label on y axis should include a line break and text in superscript, and should be centered. frame ( fac=rep (LETTERS [1:10], 100), x=rnorm (1000) ) ggplot (df, aes (x=x)) + geom May 24, 2022 · Key R functions: Using a supplementary y-axis to show the line labels To produce a second axis on the right, the ggplot2 scale y continuous () method is combined with the option sec. ggplot: Insert linebreak when label is too long. 2. major in my trivial example below, the two plots below don't have those (but you should add those in if you need them). or as x argument to guides) to overcome the over-plotting problem by dodging the labels vertically. See this question for more details on justifications and their values (What do hjust and vjust do when making a plot using ggplot?). 5, 7. Jan 29, 2022 · Here we will see two different ways to wrap long axis labels into multiple ways. breaks. If you make the y-axis have breaks for each discharge you'll actually end up getting labels stacked on top of each other which is not very useful for the user of the plot. Just define your own breaks. Aug 6, 2013 · theme(panel. There are many other stackoverflow questions about minor ticks that Aug 25, 2016 · I have recently started using ggplot2, and I am depending on help manual to understand how ggplot2 works. – Nov 25, 2019 · I would like to adjust the x axis ticks and labels so that there are two labels "Low X" and "High X" with just one tick in between them. Among the possible values, there are : NULL : hide all breaks waiver () : the default break computation a character or numeric Sep 17, 2021 · "Nice looking labels" is subjective and a harder problem than it might sound. But what do I have to do to contol the y axis major grid lines as well so they are not set automatically (for example in units of 10s, so When the function has two arguments, it will be given the limits and major breaks. Having Two or More Line Breaks and Italicized Words in Axis Labels in a 'ggplot()' Plot in R. しかし. a ggplot2 barchart with default axis labels. With ggplot2 probably this is not required. This will automatically add line breaks after X characters in labels with lots of text—you just have to tell it how many characters to use. element_rect. breaks. scale_x_discrete(breaks = ID[c(T,F,F)]) +. 1. Total' xmean <- 123. The annotate () method can be used to add both text as well shapes to the plots and data visualizations. I tried to plot "Chromosome" against "Value" but the data points become stacked as shown below. Under the hood, the package uses the gridtext package for the actual rendering, and consequently it is limited to the feature set provided by gridtext. n. 0,0. I believe this corresponds to the css properly line-height, which when reduced will bring lines closer together as the line height is smaller. The code below demonstrates how to add additional axis tick marks without labels to a ggplot2 graphic. #Our transformation function. scale_x_ and scale_y_ to change the axis type. First, let us load tidyverse suit of R packages. We’ll show also how to center the title position, as well as, how to change the title font size and color. Sep 4, 2017 · is it possible to manually add breaks and labels to the secondary y-axis using ggplot2? (see bottom right) I want more compact breaks on the right y-axis, representing the bars. default argument. I propose putting label markers on each point so that you can keep the y-axis clean while still conveying information to your users. Problem with the option2 is that it gives this illusion of drastic difference between Mar 2, 2015 · 1 - Solution with two atop calls. I am making a chart with ggplot and can control the y axis minor grid lines. This function has a breaks parameter that takes a vector as input which has all the points of y-axis break as vector points. With a scale transform, the data is transformed before properties such as breaks (the tick locations) and range of the axis are decided. 2 up to limit of y axis which is 0. One is to use a scale transform, and the other is to use a coordinate transform. Labels are printed upright, avoiding overplotting, squeezing of plot area is reduced. 1 where four Dates shown but #2 and #4 should be skipped. Here is a ggplot2 scatter plot with y-axis break using the scale_y_continuous() function. scaleFUN <- function(x) sprintf("%. If the level attributes have multiple words, there is an easy fix to this that often makes the axis labels look much cleaner. tag can be used for adding identification tags to differentiate between multiple plots. 7. titles, labels, fonts, background, gridlines, and legends. However, I find that in plot with many facets and perhaps a formatter= statement, the labels tend to get too "dense" and overprint, for example in this picture: df <- data. To get the labels the way you want you can use: hjust = 0. breaks = 10 (assuming I have a min of 1 and max of 10), I would like to specify something like break. Used for text manipulation. 1 to be part of the y-axis, or if you just want a way to label the line. Change the appearance - color, size and face - of titles. From the documentation, I see that the 'labels' argument can be "A function that takes the breaks as input and returns labels as output. g. The number of rows (for vertical axes) or columns (for horizontal axes) that should be used to render the labels. There are a few options, including: use a function like ggrepel::geom_text_repel to automatically shift labels from overlapping each other. Basically two main functions will allow to customize it: theme() to change the axis appearance. May 13, 2019 · ggplot2, tidyr. By executing the previous syntax we have created Figure 1, i. This achieves the desired result for the line, however the labeling in the x-axis is very busy and difficult to read. 0. Let say I want to print a week worth of data from 01-Jan-2019 at 00:00 through 08-Jan-2019 at 00:00. Source: R/annotation. label – The character string to add Theme elements: element_line. Note that since I did not specify panel. pos=2) I think this is also a important contribution. First make your plot. For this, we can use the seq() function as shown below: For situations where breaking the labels into two parts would still not suffice, I would also like to know how to print only every other label. Always ensure the axis and legend labels display the full variable name. We cannot render 2 geom_labels with different y values, as the vertical positioning doesn't remain consistent with 2 geom_labels when resizing the Mar 31, 2015 · To color labels I use ggh4x::guide_axis_color as in vanilla ggplot2 it is not officially supported to pass a vector of colors to axis. Most often used for backgrounds and borders. This is useful for displaying labels that would otherwise overlap. ggplot generally does a good job of creating sensible breaks and labels in scales. But it is good to have too. I demonstrate four different approaches for this: 1. geom_line(data=df, aes(x=date, y=value)) +. (1) function by hadley srt=45, ## angle. 4 discusses binned position scales. We will use the last option, a function that takes breaks as an argument and returns a number with 2 decimal places. It's common to use the caption to provide information about the data source. 1 and axis label customisation in Section 10. 23 May 26, 2015 · 8. ggplot(mpg, aes(cty, hwy)) + geom_point() I have tried changing the value of many parameters with theme() but none seems to help. I gave more explanations about this approach and also using ggplot2::annotation_custom() in ggplot2 two-line label with expression. So, there is no need to start an axis at 0 (except for bar charts and alike). Set a logarithmic axis scale. However, from what I gather you'll have to specify the axis labels and positions yourself, by hand. In this article, you will learn how to set ggplot breaks for continuous x and y axes. Allowed values are : Dec 29, 2014 · I have also had difficulty printing greek unicode as axis labels, so in these cases I resorted to annotate() with the option coord_cartesian(clip = "off") to ensure that the labels printed below the axes do not get clipped ("on" is the default clipping behaviour). Having Two or More Line Breaks and Italicized Words in Axis Labels in a 'ggplot()' Plot in R Jan 21, 2012 · Q. 0, 0. To add space between the legend keys, you can use the legend. for example I have tried both scale_x_continuous and scale_x_discrete, specifying labels and limits, but so far I haven't been able to get around the requirement that there be the same amount of labels and Now, we can plot our data as follows: ggp <- ggplot ( data, aes ( x, y)) + # Create ggplot2 barplot. option1: ylim(0. This release is a large one, so we have split the updates into multiple posts. In case of functions, if the labeller has class labeller, it is directly applied on the data frame of labels. Here is written how to write a function (1) for it, but sadly I do not know where to put labeller=label_wrap in my code (2). It is possible to transform the axes with log, power, roots, and so on. – Apr 5, 2020 · As you can see, regardless of whether your data is a fraction of 1 or a true percentage the data is scaled correctly. To clean this up (1) clip the plotting area with coord_cartesian(), (2) remove the axis labels and add a wider margin at the bottom of the plot with theme(), (3) place axis labels indicating quarters underneath the plot, and (4) underneath those labels, place annotation Line chart with labels at end of lines. Add line break to axis labels and ticks in ggplot. Create an annotation layer. Support is provided for Markdown both in theme elements (plot name: x or y axis labels; breaks: control the breaks in the guide (axis ticks, grid lines, …). scale_x_date(date_breaks = "1 week", date_minor_breaks = "1 day",) You can change the formatting of the weekly label by using the date_labels argument, e. 8) Sep 1, 2022 · Example 1: Use scale_x_continuous with Custom Axis Breaks. 2f", x) #Plot. Jul 24, 2016 · The following code works on my computer and gives you weekly ticks. R. This posts outlines changes to axes; see the main release post to learn about other changes. I solved the problem with the solution in the previous question, which is: I used this to mask a continuous variable as a categorical so I could use geom_line. This blogpost will guide you through all the steps to produce a beautiful lineplot with highlighted groups and explain how ggrepel and ggtext are a huge help that make customized plots much Jul 15, 2018 · The functions scale_x_discrete () and scale_y_discrete () are used to customize discrete x and y axis, respectively. For example, if we wanted to modify the plot above such that the title was “ \ (Y \sim X\) ”, the x axis was labeled as “ \ (\beta_0\) ,” and the legend title read “Values of \ (\mu\) ,” we could run the following: ggplot The axis usually looks very good with default option as you can see here. This is useful for adding small annotations (such as text labels) or if you have your data in vectors, and ggplot2で軸関連のコントロールをしようとすると結構こんがらがる. Allowed values are : I'm having a lot of trouble getting all three lines of the x axis labels to appear on my graph. adding secondary y-axis with different breaks and labels. Changing x-axis tick labels ggplot2 not working, making axis Nov 11, 2018 · This article describes how to add and change a main title, a subtitle and a caption to a graph generated using the ggplot2 R package. axis. Jul 26, 2019 · After looking at many examples and lots of trying, I'm still failing to combine text strings and an expression into ggplot2 axis labels to exactly what I want. Syntax: annotate ( “text” , x , y , label ) Arguments : x, y – The coordinates to add the text at. |. As a first step, we have to specify the breaks (i. right and other approaches, e. 95 (to leave some space between the labels and the axis) Jul 11, 2012 · 3. Table of contents: 1) Example Data, Packages & Default Plot. To get the labels on x axis in monthly format: ("Jan 2000" to "Jul 2020") Oct 17, 2013 · Sometimes when plotting factor variables in R, the graphics can look pretty messy thanks to long factor levels. . Get the last values vector. Make a line graph with labels. 5) and give them an empty label. It should look like: "Density of mobile invertebrates (indiv. Jan 19, 2018 · If you want more grid lines, you could always define additional breaks (say at positions 2. If it is not, and you want to force the graph to display the Y axis from 0 to 100 (with breaks every 20) – for example to equalise the axes of multiple plots displayed side-by-side – add limits=c(0,100) like so: + scale_y_continuous(limits=c(0,100), breaks=seq(0,100, by = 20 Apr 3, 2020 · I am trying to plot a graph in ggplot2. ggplot(df, aes(x=points, y=assists)) +. Otherwise, it is applied to the columns of the data frame of labels. The line is not split in two lines. The vector of values matching the line ends determines the numbers to be displayed at breaks. A constraint I have is that the labelling should be done "in-place" without pre-processing of the data. Mar 8, 2019 · In order to add math notation to those labels, we can use the expression() function to specify the label text. 1) Third, pretty() turns this sequence into a sequence of "pretty" values (meaning 1, 2, or 5 times a power Apr 7, 2016 · To increase the axis-line thickness and change the color to black: axis. We are pleased to release ggplot2 3. dodge = 2) (as guide argument to scale_. a) x-axis Here's what I did: df <- data. We'll just label the bottom tick with "0". Good labels are critical for making your plots accessible to a wider audience. 3. y. ". , using %D gives you m/d/y, as follows. frame and/or labels, though a custom function applied within the call to ggplot would be fine. I want the Details. However, the package ggthemes offers Tufte style axes which might be an alternative to the solution the OP is asking for: May 8, 2020 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand May 8, 2019 · I have a time series (hourly) data, and I want to print selected period of that data. This is clearly not the most beautiful code, but this is basically the functionality I'm looking for where the labels on the y-axis encompass the data completely. Feb 28, 2024 · Teun van den Brand. This only works if your data is already ranging from 0 to 100. To solve your issue, you should specify the years either as a sequence or just a vector of years as Aug 14, 2013 · You can easily use line breaks in regular paste, but this is plotmath paste (actually a different function also with no 'sep' argument) and the (long) ?plotmath page specifically tells you it cannot be done. I would like to plot "Region" (x-axis) against "Value" (y-axis), adjust the data point shape according to "Region", but change the x-axis label according to "Chromosome". However, legends are more complicated than axes, and consequently there are a number of topics that are specific to legends: A legend can display multiple aesthetics (e. ggplot2: How to add linebreak to horizontal legend. Something like this may do what you want (will need some fiddling most likely): Jan 2, 2017 · Align multi-line axis title in ggplot2. Allowed values are : Nov 17, 2017 · This chapter provides a cheat sheet to change the global appearance of a ggplot. what I am trying to get here is the x-axis label to be: the ingredients: parname <- 'FL. Section 10. ticks = element_line(colour = "black", size = 2) To add minor ticks: Minor ticks are not currently an option of ggplot2. What am I doing wrong? Nov 9, 2021 · Method 1 : Using annotate () annotate () method in R is used to insert framed text into the plot. The data frame is then processed with the function specified in the . Red. It's not clear if you want 7. You will learn how to: Add title, subtitle, caption and change axis labels. key. Using facets, which is built in to ggplot2 but doesn’t allow much control over the non-shared axes. They control the horizontal and vertical justification respectively and range from 0 to 1. The plot is listening to my instruction for the x axis limits and breaks, but I can only get it to listen to either the limits OR the breaks for the y axis. It covers limits, breaks, and labels in Section 10. grid. 10. Jun 23, 2022 · Option F: Automatically add line breaks. line = element_line(colour = 'black', size = 2) To increase the tick thickness: axis. Set the axis limits. You can pass any parameter of scale_y_continuous() to scale_y_pct(), e. Themes are a powerful way to customize the non-data components of your plots: i. break function in the plotrix package which implements broken axes. ggplot2でプロットを行っていると、見やすさやレイアウトなどの観点から軸関連の設定を変えたいときがあります。. height theme element. 2) Example 1: Modify Minor Grid Lines on X-Axis of ggplot2 Plot. The ggtext package provides simple Markdown and HTML rendering for ggplot2. In the simplest case they map linearly from the ggtext: Improved text rendering support for ggplot2. 4) Example 3: Modify Major Breaks & Grid Lines on Y-Axis of May 4, 2022 · Sorry I do not know how to enter data here. Simplified code example in the following and its output in Fig. Whether to draw the minor ticks ( TRUE) or not draw minor ticks ( FALSE, default). 5)) +. insert line breaks of long labels. 1 Numeric position scales. dat<-data. It works by starting from an initial point and iteratively nudging until the labels have as much separation as you've specified. labels=lab, ##labels. Without Line Breaks Here’s the messy looking example: I'm trying to make the x-axis the actual years instead of ggplot2 break them up into halves. So instead of something like breaks = seq(1:10, 1) or n. This is intended to be used with functions taking a character vector Sep 3, 2022 · By using the line break syntax ( \n) we are able to create a multi-line subtitle. Let’s see how to use them. breaks : control the breaks in the guide (axis ticks, grid lines, …). Here's an example with the built-in iris data frame: Here's an explanation: First, The breaks argument in scale_y_continuous() can take the form of a function of the plot's input data (x in this case) Second, seq(0, (max(x) + 1) * 1. So lets say your plot looks like this: One idea would be to hide every 3rd label from the x-axis by modifying the break argument of the axis: ggplot(df, aes(x = factor(ID), y = A)) +. Jul 3, 2015 · The y-axis title appears too close to the axis text. Objective: Customize tick marks in graph. The only thing I added was y-axis formatting and an axis line theme. So, here we can set the axis breaks point to a plot manually. As you can see, the axis labels are very long and are partly overlapping each Apr 7, 2020 · While I disagree with your reviewers, you can get down and dirty with the underlying grid graphics if you truly want a y-axis break. increments = 1. Axis labels Each axis will have automatic axis labels or texts. Theme element: line. Axes, alongside legends, are visual representations of scales and allow observers to read values off of a plot. For instance, the default axis labels for the Y-axis of our example ranges from 100 to 300 with a step size of 50 and the labels of the X-axis are the names of the different groups (A, B and C). The word 'Lawn', which should appear under 'Sphagnum', is lost. scale_y_continuous(minor_breaks = seq(0, 100, 5)) ch2. Since the word 'Sphagnum' needs to be italicized, I can't simply use the standard line break (\n). Use the plot title and subtitle to explain the main findings. 34 xsigma <- 2580. 6) option2: scale_y_continuous(breaks=seq(0. Aug 9, 2012 · 31. Nov 21, 2016 · We could also call cowplot::draw_label() two times (inspired from this discussion). . There are a variety of ways to combine ggplot2 plots with a single shared axis. using ggtext require slightly more work. Plotting "Region" against "Value" would create Mar 25, 2021 · We need to reduce the gap between the two rows of text. colour and shape), from multiple layers (Section 14. This will simulate minor grid lines but at exactly the locations you want. Furthermore, in both cases no decimal is displayed as all labels are integers. xpd=TRUE, ## allows plotting outside the region. You can use str_wrap for automated wrapping of long strings or you can hard code breaks by adding \n (the line break character) to a string. Use the themes available in complete themes if you would Oct 9, 2012 · 100. Themes can be used to give plots a consistent customized look. 軸に関連する設定はscale_関数やtheme関数などをまたいで行われる Jul 17, 2017 · I want to show every second of x-axis label list in the presentation. the tick marks) that we want to use in our plot. Adding line breaks between words to axis labels in ggplot. With this option you don't have to change your data but just define a labeler in the scale that does everything for you, this is handy if you want to color the x-axis in many similar plots with different data. I tried two options. Also a better and elegant solution with grid is given in the R Graphics book by Paul Murrel. As mentioned here, every time we call atop() the text gets smaller, but also the gap between the lines. Elements. 1) First we make a sequence between 0 and the maximum value of the x-axis, plus some extra padding ((x+1)*1. Any suggestions are most appreciated. Dec 4, 2023 · But what if I want to customize the x-axis breaks? What if I want a break at every multiple of 2 instead of 5? I've looked around a lot, and haven't yet found a way to customize the breaks when the x-axis limit is fixed. 2. Use NULL to use the default number of breaks given by the transformation Jan 19, 2022 · While creating a graph with ggplot2, I'm having trouble to format the x-axis which are dates that show as numerical values. Among the possible values, there are : NULL: hide all breaks; waiver(): the default break computation; a character or numeric vector specifying the breaks to display; labels: labels of axis tick marks.
uq ui xb iv kt zg ij ju xm tv