Quickplotter beta
How to plot effectively with Quickplotter?
This guide includes several tips and tricks that go beyond the simple tooltips on the main page and help you to make the most of Quickplotter.
Function transformations
The custom functions allow flexibility in mutating the x- and y-values before plotting while keeping the original imported data unchanged. Here are some common questions and use cases related to function transformations:
Which mathematical expressions are recognized?
Quickplotter uses math.js for parsing the mathematical expressions in data transformations and curve fitting. Check the reference for the supported functions and operators.
How to normalize y-values between 0 and 1?
Use the following transformation (y - min(y)) / (max(y) - min(y)).
How to shift the center of x-values to zero?
If the x-coordinates are evenly spaced, the simple transformation x - mean(x) works. In the general case, use x - (max(x) - min(x))/2.
How to plot linear scale y-values in dB-scale?
Quickplotter does not yet support plotting the axes in logarithmic scale but you can use a function transformation to make the data logarithmic. The following function works: 10*log10(y). Negative or zero y-values are illegal arguments to logarithm and result in NaN:s which are dropped out before plotting.
How to use logarithm to explore power laws in your data?
Suppose you have dataset that you believe obeys a power law y = ax^k and you want to find the parameters a and k. Instead of turning straight into curve fitting, it makes sense to first transform your data into log-scale with log(x) and log(y). Now your function has to form log(y) = k*log(x) + log(a) and you can use a linear fit to find the slope = k and intercept = log(a) easily.
How to draw mathematical functions?
Quickplotter is not a graphing calculator but you can use the custom function transformation to plot pure mathematical functions, such as f(x) = exp(x), if you import linearly spaced data. For example, you can generate two columns with x=y=1,2,...,100 in Excel and then transform the y-values in Quickplotter to exp(y).
Unicode characters
How to write Unicode characters?
The graph title, axis labels and legend entries can render Unicode characters given as HTML entities or decimal or hexadecimal references. At the moment, the legend position is not correctly calculated if the legend contains special Unicode characters. See this link or google for a reference of possible character codes.
Greek letters
Greek letters have their own HTML entities so they are easy to remember. For example, a lowercase alpha (α) is α and an uppercase sigma (Σ) is Σ. Greek letters look much nicer in serif-fonts, such as Times New Roman.
Characters without an HTML entity
If a character does not have an HTML entity, you can use its numeric reference. For example, ∓ draws the minus-plus sign (∓). In principle, you can use any character, even the Snowman (⛄ = ⛄), though I doubt you will need it.
Importing and exporting
How to import data?
You can import data either by copy-pasting or drag-and-dropping into the figure area. The drag-and-drop method allows importing multiple files simultaneously. If you want to import error values, select the correct import format first.
How to export data?
Quickplotter provides three export options: PNG figure for instant use, SVG figure for further modification and CSV data file to save transformed raw data or fitted curves.
How to edit the figure generated by Quickplotter?
Quickplotter aims to provide the most commonly used styling options but f you want full-control over the look of you graph, you can export it in SVG-format for post-processing in a vector graphics editor. The free, open source, cross-platform editor Inkscape. is a great option. Please use the newest version of Inkscape, 0.92. In addition to styling, you can use Inkscape to add annotations to your graphs or combine several graphs into a single file.
How to export a figure with a certain aspect ratio?
By default, the figure fills the entire available area in the browser window and the exported figure will inherit these dimensions. You can use the "fix aspect ratio" option to uncouple the aspect ratio from the browser window. If you need a figure with exact pixel dimensions, you can export as SVG and scale the figure in Inkscape.
How to give feedback or suggest new features?
If you find Quickplotter useful, or if you feel that some essential feature is missing, I'd like to hear about it. You can email me (the address is in the side bar) or open a new issue on GitHub. Your suggestion has a good change of being heard. For example, the error bar plotting was added based on user feedback.