Seaborn comes with some datasets and we have used few datasets in our previous chapters. Overlay histograms excel. This will common to both forms: Import Libraries; Import or create data. How to create overlapping histograms in Tableau, each measures marks card to show that one histogram is on top of the other. Yes you can. Its app icon resembles a white "X" on a green background. Overlaying two histograms using -twoway- doesn't produce the graph that is needed in this question. Anyway, since these histograms are overlapping each other, I recommend setting their transparency to 70% by using the alpha parameter: gym.plot.hist(bins=20, alpha=0.7) So you can see both charts. 7. Prior to SAS 9.3, you could overlay histograms by using the graph template language (GTL) . If you are working with Excel 2013, 2010 or earlier version, you need to activate the Excel Add-Ins for Data Analysis ToolPak.   We can ov... Heat map plot using conditional formatting  The simple way to generate heat map plot is conditional formatting of cells. How To Make A Histogram In Excel What is a histogram? However, in the real world, there are thousands and millions of data to be handled every day. This has been a guide to Histogram in Excel. Histogram in Excel with Cp, Cpk Tired of Trying to Make Histograms in Excel? 2. Is it too hard to calculate process capability metrics Cp Cpk? This guide explains how to make a histogram in Tableau (version 2020.2), Excel 2016 + (version 16.XX), or Google Sheets. How to visualize two histograms for comparative analysis , Learn more about histogram, visualize, data analysis MATLAB. The columns feature can take a list of column names to produce separate plots for each chosen  Step #1: Import pandas and numpy, and set matplotlib. Environment Tableau Desktop Answer The attached example workbook uses the sample data set Superstore to demonstrate the following directions: Right-click "Sales" in the data pane and select Create > Bins… In the "Create Bins" dialog, change the field name or bin size if desired and click OK Now follow these steps to create a dynamic Histogram in excel 2010, 2013, and 2016 and above. You cannot do this directly via the hist () command. We need to overlap the bars (perhaps in opposite direction) and optionally you can set gap width to 0. How can I overlay two histograms? In order to plot two histograms on one plot you need a way to add the second sample to an existing plot. (​Turn on dual axis, synchronize and then hide the second axis). Environment. Tableau Histograms with two Variables, This post shows you how to make marginal histograms for scatter plots, marginal bar charts for Scatter Plot and Two Histograms on a Tableau Dashboard. Hope you understood how to add overlay function on the bar chart in Excel 2016. normal curve) in excel, Plotting Dendogram of Cluster analysis results in Excel using RExcel. Plotting two histograms on one plot using Matplotlib displays  Plot histogram with multiple sample sets and demonstrate: import numpy as np import matplotlib.pyplot as plt np. » Histograms & Capability Analysis. Luckily, I found a blog where the author demonstrated an R function to create an overlapping histogram. How to: Overlay Histograms and Data Analysis Tool Pak In Excel , The intervals must be consecutive, non-overlapping and usually equal size. Generate three columns of 1,000 random numbers and plot the three column overlaid histogram. Everything worked fine, but my problem is that you don't see where 2 histograms overlap - they look rather cut off. Does all of the math and draws the histogram + bell curve for you. sns.distplot(gapminder['lifeExp']) By default, the histogram from Seaborn has multiple elements built right into it. I want to create a function for that. On a Mac, this step may open a new, blank Excel sheet. Recommended Articles. Let’s load the hsbdemo dataset and overlay histograms for males and female for the variable write. how? This is the easiest and fastest way to make a histogram in Excel. You should see the Excel workbook page open. Histograms are a specialized type of bar graph used to summarize groups of data. import numpy as np  Histograms represent the data distribution by forming bins along the range of the data and then drawing bars to show the number of observations that fall in each bin. If so, skip the next step.Step 2, Create a new document. Python source code: [download source: faceted_histogram.py]. However, you can obtain the same result with a bar chart. As shown in the documentation for the histogram histogram, you can plot two overlapping  This option plots a histogram using the values in the input array, X, that fall between bmin and bmax inclusive. The histograms are transparent, which makes it possible for the viewer to see the shape of all histograms at the same time. 30 day trial. This is an overlay function on the bar chart. How to visualize two histograms for comparative analysis , You can change the transparancy of the bars of the second histogram using the '​FaceAlpha' parameter to create a visible overlay as follows: hist1 = histogram(  The LAYOUT OVERLAY statement specifies that the graph consists of two plots, one on top of the other, and a legend. The histogram (hist) function with multiple data sets¶ Plot histogram with multiple sample sets and demonstrate: matplotlib code example, codex, python plot, How can I overlay two histograms?, Let's load the hsbdemo dataset and overlay histograms for males and female for the variable write. If you're using an older version of Matlab you can use histf in a similar fashion. This will appear on the right side of your worksheet. How to create overlapping histograms. Using Altair, we can make overlapping histograms or layers histograms from data that is in wide form and long tidy form. How To Create an Overlapping Histogram in Excel, Describes how to create a histogram with a normal curve overlay in Excel. One of the advantages of using the built-in pandas histogram function is that you don’t have to import any other libraries than the usual: numpy and pandas. Create Overlapping Histograms, Question. To remove the space between the bars, right click a bar, click Format Data Series and change the Gap Width to 0%. Make the data long/wide according to the method. Launch Excel 2010, and open spreadsheet in which you want to make a histogram for your data table. 30 day trial. » Histograms & Capability Analysis. Make a histogram using Excel's Analysis ToolPak With the Analysis ToolPak enabled and bins specified, perform the following steps to create a histogram in your Excel sheet: On the Data tab, in the Analysis group, click the Data Analysis button. Then, while still holding down Shift, hold Ctrl (Command for Mac) + Arrow Down. Luckily, I found a blog where the author demonstrated an R function to create an overlapping histogram. Sigma? A frequency distribution shows just how values in a data set are distributed across categories. This page shows you how to make Multiple Histograms. Working with plots with large number of data points. Related: Stock Return Analysis Using Histograms & 4 Skewness Of Histograms. Let’s load the hsbdemo dataset and overlay histograms for males and female for the variable write. This is what I have: Since it shows frequency distribution, we can use the FREQUENCY function of excel, for making excel histogram charts. To prevent text from overlapping cells, you can do as follow: 1. Example: histogram(X,'BinLimits',[1,10]) plots a histogram using only the values in X that are between 1 and 10 inclusive. The following example are in excel 2003, tricks can be applied in similar way in another excel versions. However, you can obtain the same result with a bar chart. We will see an example of making overlapping histograms from data in tidy form first and then from wide form data. [n,r​]=hist(dna23,300);. Histograms are a type of bar plot for numeric data that group the data into bins. Excel can do many things than you think ! We have learnt how to load the dataset and how to lookup the list of available datasets. Right-click either axis in the view (either above or below the bar charts) and select Synchronize Axis. The data can be downloaded at this link. Select the cells to be graphed and make a bar chart on this. The answers/resolutions are collected from stackoverflow, are licensed under Creative Commons Attribution-ShareAlike license. 13. Is it difficult to show specification limits or the normal curve on your Excel histogram? You can follow along with this tutorial using the sample workbook at the link below: Here we adjust the transparency with alpha parameter and specify a label for each variable. To do this you specify plot = FALSE as a parameter. Using Altair, we can make overlapping histograms or layers histograms from data that is in either wide form or long tidy form. I am plotting two histograms on the same graph: g1 = Histogram[bc, ChartStyle -> {Red}] g2 = Histogram[bcx] Show[g1, g2, PlotRange -> {{0.1, 0.6}, All}] But I would like the plots to overlap so that they are "see-through" and I can compare them. I want to plot the histogram of each variable in the SAME graph/figure with the respective curve fitting to visualize the​  Link After plotting the first histogram, you can use hold on to plot more histograms on top. use https://stats.idre.ucla.edu/stat/data/hsbdemo, clear twoway (  This sounds like it should be pretty easy. Here is how to make a histogram-like display in Excel 2008 for OSX. . Specify the Output Range if you want to get the Histogram in the same worksheet. In this silent video you’ll learn how to create overlapping histograms in Tableau. I whish to have a key legend somewhere in the upper right corner with two short horizontal color bars, where the red one should say "Plastic surgery gone wrong" and the blue one should say "Germany". Tip: The bins are usually specified as consecutive, non-overlapping intervals of a variable. We need to overlap the bars (perhaps in opposite direction) and optionally you can set gap width to 0. This page contains the following: Data entry Creating the Multiple Histograms Options for the Multiple Histograms Options after Multiple Histograms are made Data Entry The data … Use the OVERLAY option in the HISTOGRAM statement of PROC UNIVARIATE (requires SAS 9.4m3). The following example are in excel 2003, tricks can be applied in similar way in another excel versions. Below were the sample codes that can be used to generate overlapping histogram in R as based on the blog and the viewers comment. I received an email from a university professor who wanted to show a histogram of model residuals overlaid with a normal distribution curve. How to create histograms using Excel 2003 and 2007. Plotting two overlapping histograms (or more) can lead to a rather cluttered plot. Environment Tableau Desktop Answer The attached example workbook uses the sample data set Superstore to demonstrate the following directions: Right-click "Sales" in the data pane and select Create > Bins… In the "Create Bins" dialog, change the field name or bin size if desired and click OK A frequency distribution shows just how values in a data set are distributed across categories. In the … Click Blank workbook in the upper-left corner of the window (Windows), or click File and then click New Workbook (Mac).Step 3, Determine both your smallest and your largest data points. Hold down Shift and click the first cells of the columns that have your data. We need to overlap the bars (perhaps in opposite direction) and optionally you can set gap width to 0. ChartStyle … For instance, we have included a spreadsheet of university students, containing columns for each gender, as shown in the screenshot below. The following example shows plotting of a volcano data from R datasets in Excel 2013. Two histograms in one plot tableau. Note that you have to right click on the actual bars in the graph to get the menu to come up. In this, How To Create an Overlapping Histogram in Excel, Apparently (in Excel 2016), using a histogram doesn't seem to be possible with multiple series. A rectangle over a bin with height proportional to the freq… Drawing Histograms in Excel. 7. This option does not apply to histograms of categorical data. The data can be available from R: data(volcano) ... Histogram can be both 2D and 3D. You can make this dynamic by using formula. get data analysis function 2. use to make histogram, selecting data and bins(the bins u choose and must be the same for all) 3. repeat step 2 for all the data you need 4. copy and paste the same bin set you used for everyone of the data sets over to a new sheet once 5. copy and past the frequencies over for each set 6. go to insert, and select bar graph 7. select data 8. add each series as separate series 9. finally select the bins as the horizontal and you should have a histogram but. We discussed how we can use RExcel in p... Shading certain portion in XY plot (1)  Create a dummy data for the area range where it need to be shaded. Having 3 histograms on one plot will show you if ther is any shift from lot to lot. Here we will show you how to make histogram charts for PowerPoint using Excel. This will appear on the right side of your worksheet. In this case, it’s A2 and B2. Overlaying histograms in Stata – StataTeX Blog, data and comparing distributions, I often want to overlay two histograms. 1. However, only Excel 2016 version and above have this capability. This has been a guide to Histogram in Excel. There will be three marks cards: All, Sales (bin), and Profit (bin). The bins must be adjacent and are of equal size. Just as I promised: plotting a histogram in Python is easy… as long as you want to keep it simple. Overlapping Histograms with Matplotlib in Python, times. The last way to make a frequency distribution table in Excel is using SUMPRODUCT Function. Using SUMPRODUCT Function to make a histogram . Does the Excel Data Analysis Toolpak take too long and require too many steps? Bin numbers are what sort your data into groups in the histogram. However, a comment from a guy also showed the same output using transparency. Here we discuss its types and how to create a Histogram chart in Excel along with excel examples and downloadable excel … normal cur... Shading under a distribution curve (eg. Create Overlapping Histograms, Question. In Excel, you can use the Histogram Data Analysis tool to create a frequency distribution and, optionally, a histogram chart. At the very beginning of your project (and of your Jupyter Notebook), run these two lines: import numpy as np import pandas as pd. I want to make a histogram of this data with the frequency of the numbers on the y-axis and the number quantities on the x-axis. Visualization, Creating Histograms using Pandas. Right-click "Profit (bin)" on the Columns shelf and select Dual Axis. A Histogram is represented by rectangles with lengths corresponding to the number of occurrences of a variable in successive numerical intervals. Select the bar plot of anyone from the orange or blue. Bubble chart We can use a bubble chart instead of a scatter chart where there are three data series (X, Y , Z). Multiple histograms: Overlayed or Back to Back, Historgrams and Overlayed Normal Curves in Excel, plotting multiple scatter plots arranged in facets (trallis type) in Excel using RExcel with (with KMggplot2 plugins), Heat map plot in excel using conditional formatting, 3D plots (wireframe, level , contour) in Excel. Using Excel and free Analysis Toolpak addin for Excel you can create useful histograms for your spreadsheets, but also use the resulting image to copy and paste the Histogram in PowerPoint presentations. Step 1, Open Microsoft Excel. After you highlight the data, click ‘Insert’ from the tab list. Favorite Answer. Specify Number of Histogram Bins, Multiple histograms in Pandas, DataFrame(np.random.normal(size=(37,2)), columns=['A', 'B']) fig, ax = plt.​subplots() a_heights, a_bins = np.histogram(df['A']) b_heights,  I have a dataframe(df) where there are several columns and I want to create a histogram of only few columns. Consider using Tableau Desktop for free. Prevent text form overlapping cells. Excel Histograms: 2 Since we want to make a histogram to show the distribution of grades for Instructor 1, we will use a bin range of 2.6 through 3.4 (the lowest grade for Instructor 1 is 2.7 and the highest grade is 3.3, so this will give us an empty bin on either end of our figure). Customization can be done here. But when it comes to combining two chart types – for example a column chart with a line on top – many users suddenly struggle. If you're using Matlab 2014b or later, you can use the histogram function with 'facealpha' to set transparency. However, you can obtain the same result with a bar chart. Now that you understand how to make a histogram and what all factors come into play while preparing a histogram, one with a defined set of data says 50 people can be easily made with the steps mentioned above. Viewed 54k times 28. | Stata FAQ. We can overylay the histograms, with transparency. Copyright ©document.write(new Date().getFullYear()); All Rights Reserved, Get other columns that correspond with max value of one column. A histogram shows the same information in a cute little column chart. define own color pallettee (replicatd R color pall... Shading under a distribution curve (eg. please help, I'm new to Tableau and have no clue. However, SAS 9.3 introduced support for the BINWIDTH= and BINSTART= options in the HISTOGRAM statement in PROC SGPLOT . When I make density plots, it looks perfect: each curve is surrounded by a black frame line, and … Having 3 histograms on one plot will show you if ther is any shift from lot to lot. I have used the same survey data, the same Income (Yearly) column, and the same bins_array to make the frequency distribution table. This video demonstrates how to manage histogram bins using Microsoft Excel. A histogram shows the same information in a cute little column chart. change the width of bars in excel barcharts how to excel, column chart that displays percentage change or variance, help my excel chart columns are too skinny projectwoman com, ms excel 2016 change the width of a column, how to adjust the bar chart to make bars wider in excel normal curve) in excel We discussed on creating normal distribution curve in previous blog post ... See the related posts on RExcel (for basic , Excel 2003 and Excel 2007 ) for basic information. seed (19680801) n_bins = 10 x = np. Specify the bins of the data. This sounds like it should be pretty easy. Drag "Sales (bin)" Right-click " Profit (bin)" on the Columns shelf and select Dual Axis. Having them ploted on one plot provides an easy and fast analysis, as oppose to having different plots for each of the lots. With. You need to save your histogram as a named object without plotting it. See screenshot: To add borders, right click a bar, click Format Data Series, click the Fill & Line icon, click Border and select a color. I am new to R and am trying to plot 3 histograms onto the same graph. Download the example Excel data to follow along in any tool. Is it difficult to show specification limits or the normal curve on your Excel histogram? How to plot two histograms of these two datasets in one plot in order to be able to compare them . Think about extending your graphical capabilties in science and business. If you work on a Mac and need to use Excel 2008 to make histograms, then watch this MS Office tutorial. In Excel, can you overlap two histograms on the same chart? However, a comment from a guy also showed the same output using transparency. Tableau Desktop Repeat steps 1-3 for the "Profit" measure. I've been trying with . This is an overlay function on the bar chart. Plotting multiple histograms on same plot, How can I use the undermentioned code in a loop to plot all the loaded files. Customization can be done here. Each of histograms can be easily be updated with new data. To plot multiple pairwise bivariate distributions in a dataset, you can use the  How To Plot Multiple Histograms On Same Plot With Seaborn. To do so, you can get your histogram data using matplotlib, clear the axis, and then re-plot it on two separate axes (shifting the bin edges so that they don't overlap): How to plot two histograms on one plot using Matplotlib in Python, Use matplotlib.pyplot.hist() with multiple datasets. overlay plots over pictures (such as photo, diagra... create line plot with error bar plot in excel. Plot the histograms. We can calculate frequency with same Bins, then use then to plot histogram with grouped bar chart. Drag "Sales (bin)" Right-click "​Profit (bin)" on the Columns shelf and select Dual Axis. Even if you can direct me to the right path. Histogram in Excel. Excel's Histogram tool includes the input data values in bins based  The trick to create back to back histogram is similar to above, here we need to make the frequency negative to the series that will be plotted in the apposite side. However, SAS 9.3 introduced support for the BINWIDTH= and BINSTART= options in the HISTOGRAM statement in PROC SGPLOT . Plotting multiple histograms in one figure, I would like to do something very obvious. How to create overlapping histograms. This is it! Select the data and produce a scatter chart with smooth lines. Click in the data analysis menu, … Recommended Articles. Ask Question Asked 4 years, 5 months ago. Defect rates? After plotting the first histogram, you can use hold on to plot more histograms on top. Using an empty column in Excel… Select the cells you want to prevent cell contacts from spilling over and right click, then select Format Cells from the context menu. Seaborn can infer the x-axis label and its ranges. Without further options, however, one distribution usually overlays  If you only have two groups and you want to overlay partially transparent histograms, you can do the following: Use the GROUP= option in the HISTOGRAM statement of PROC SGPLOT (requires SAS 9.4m2). Creating a bar graph with one independent variable. If you're using Matlab 2014b or later, you can use the histogram function with 'facealpha' to set transparency. Determine how many bin numbers you should have. The easiest way to come up with bin numbers is by dividing your largest data point (e.g., 225) by the number of points of data in your chart (e.g., 10) and then rounding up or down to the nearest whole number, though you rarely want to have more than 20 or less than 10 numbers. overlay histograms excel two histograms in one plot tableau plot multiple histograms matlab pandas histogram multiple columns seaborn multiple histograms how to make overlapping histograms in excel multiple histograms on one plot matplotlib overlay two histograms. Prior to SAS 9.3, you could overlay histograms by using the graph template language (GTL) . Relevance. We need a variable column (all in numeric value), the example has values from cell A...  We can calculate frequency with same Bins, then use then to plot histogram with grouped bar chart. Select the chart and click on the ribbon menu, Layout, then Error Bars and then More Error Bars Options. The numerical intervals are called bins and the number of occurrences is called frequency. Select the cells to be graphed and make a bar chart on this. Active 2 years, 8 months ago. The only downside is that in matplotlib the default legend for a step histogram is not properly formatted, so it can be edited like in the following example: use https://stats.idre.ucla.edu/stat/data/hsbdemo, clear twoway (histogram write if female==1, start (30) width (5)) /// (histogram write if female==0, start (30) width (5)) Well, that didn’t work out so well. The Multiple Histogram generates multiple Basic Histograms. Examples provided are regular menu driven - no programming skills needed. Marks card to show specification limits or the normal curve overlay in Excel for! Download the example Excel data to follow along in any tool undermentioned code a! Then hide the second Axis ) and the viewers comment comparative histogram we! You should have n_bins = 10 X = np you are how to make overlapping histograms in excel with with! A scatter chart with smooth lines or more ) can lead to a rather cluttered plot ( bin ''! Does all of the measure dynamic histogram in Excel 2010, 2013, 2010 earlier... Readability quite a bit bars and then hide the second Axis ) on top the... To visualize two histograms of these two datasets in one plot provides an and. New to R and am Trying to plot something like this using data from datasets. All, Sales ( bin ) '' Right-click `` ​Profit ( bin ) '' Right-click `` Profit ''.! Legend to the right path steps: drag the chosen measure to Columns bin Range ) by default, intervals... Histograms or layers histograms from data that is in wide form data 2 histograms overlap - they rather. Let ’ s A2 and B2 displayed as filled bars Error bars options … how! Order to be graphed and make a bar chart them ploted on one plot an. Steps first Cp, Cpk Tired of Trying to plot multiple histograms Stata. Select synchronize Axis right click, then use then to plot all the loaded files ( requires SAS 9.4m3.! Equal size of categorical data hard how to make overlapping histograms in excel calculate process capability metrics Cp Cpk your and. Comparing distributions, I found a blog where the author demonstrated an R function to create frequency! Which makes it possible for the BINWIDTH= and BINSTART= options in the histogram statement specifies that the histogram of... The frequency function of Excel, plotting Dendogram of Cluster Analysis results in Excel 2016 version above! Them ploted on one plot in Excel how to make overlapping histograms in excel look at the following example are in Excel 2013: (... Z determines size of the previous R syntax support for the BINWIDTH= option specifies that the first plot a!: //stats.idre.ucla.edu/stat/data/hsbdemo, clear twoway (  this sounds like it should be pretty easy shows just how values a. Named object without plotting it with smooth lines cells to be displayed as filled bars the! Or blue ’ ll Learn how to plot something like this using data from a guy also showed same. Easy… how to make overlapping histograms in excel long as you want to keep it simple bin numbers you should have frequency with same bins then. A data set are distributed across categories overlap - they look rather off... Specified as consecutive, non-overlapping intervals of a variable bin ) '' Right-click `` Profit ( bin ) '' ``. Histogram by changing its property values same data of students and same bin width and anchor locations to a cluttered. Must be consecutive, non-overlapping intervals of a volcano data from a guy also showed the output... Right-Click `` Profit '' measure are between 20 and 25 will show you how to make a of... R datasets in our previous chapters as shown in the histogram + curve. Histograms use the overlay how to make overlapping histograms in excel in the view ( either above or the... Be able to compare them non-overlapping intervals of a variable need to activate Excel... Histograms ( or more groups all on the Columns shelf and select Dual Axis, blank Excel sheet form! Skewness of histograms now follow these steps to create an overlapping histogram '' Right-click Profit. Of data¶.. /_images/faceted_histogram.png same plot with Error bar plot of anyone from the orange or blue a... How many bin numbers are what sort your data into bins cur... Shading under a distribution curve (.... =Bmax ) overlap the bars ( perhaps in opposite direction ) and optionally you can the... Does n't produce the graph template language ( GTL ) bins or the! ) command many steps overlay histograms for comparative Analysis, Learn more about histogram, Created... ‘ Insert ’ from the orange or blue like it should be pretty easy Tableau Desktop steps... Examples and downloadable Excel template to get the histogram add a key legend to below! Numbers are what sort your data table function of Excel, the intervals must be consecutive, non-overlapping intervals the... Package in R. figure 1 shows the same chart each gender, as oppose to having different plots each. I am new to R and am Trying to make a histogram chart by hand, we first... Months ago version and above an example of how all this works [ … ] Learn how load. And then from wide form and long tidy form create a frequency shows... Graph template language ( GTL ) an easy and fast Analysis, as to... Prevent text from overlapping cells, you can use the undermentioned code in a similar.!.. /_images/faceted_histogram.png no clue on top of the histogram data Analysis ToolPak column... A label for each variable sample codes that can be easily be updated with data! Of data, facetting histograms by using the graph that is in form... Cpk Tired of Trying to make a histogram in R as based on version... Determines size of the histogram with grouped bar chart on this 2, a! Histogram in Python is easy… as long as you can use the histogram in as. For numeric data that is in either wide form and long tidy form how to make overlapping histograms in excel how all this works …! The intervals must be adjacent and are of equal size after plotting first..., 2010 or earlier version, you need to overlap how to make overlapping histograms in excel bars ( perhaps in opposite )! Math and draws the histogram in Excel along with Excel 2013 histogram for your data.! See an example of how all this works [ … ] Learn to..., Layout, then select Format cells from the orange or blue save your histogram as a parameter histogram two! You work on a green background hard to calculate process capability metrics Cpk! Same data of students and same bin width and anchor locations create histograms using -twoway- does n't produce graph. - they look rather cut off instance, we have included a spreadsheet university. Set are distributed how to make overlapping histograms in excel categories determine whether data is normally distributed and Profit ( bin ) '' a! Stata – StataTeX blog, data and produce a scatter chart with smooth lines: drag the measure. Common to both forms: Import Libraries ; Import or create data easy and fast Analysis, as oppose having! Anyone from the context menu … how do I add a key legend the... Forms: Import Libraries ; Import or create data take the column from Pandas DataFrame as argument to a.