Data visualization can help us explore, understand, and gain insight from data. Visualization can complement other methods of data analysis by taking advantage of the human ability to recognize patterns in visual information. Turi Create provides one- and two-dimensional plotting capability, as well as an interactive way to explore the contents of a data structure.
Turi Create data structures can also be used with other visualization libraries like matplotlib. You can use any Turi Create data structure with matplotlib and other libraries by converting to a Python list, Pandas DataFrame, Pandas Series, and/or numpy array, depending on what the library expects. In this section we'll focus on the built in visualization methods in Turi Create, which are purpose-built for the types of data visualization commonly used in machine learning tasks, and support very large datasets through streaming aggregation.
There are three primary visualization methods in Turi Create:
showproduces a plot summarizing the data structure; the specific plot rendered is determined automatically by the type of data structure, the underlying type of the data structure (
dtype), and the number of rows of data. See SFrame.show and SArray.show.
turicreate.show(x=, y=)produces a two-dimensional plot of an SArray on the X axis, and an SArray on the Y axis. The specific plot rendered is determined automatically by the underlying
y. See turicreate.show.
exploreopens an interactive view of the data structure. For SFrame and SArray, this takes the form of a scrollable table of rows and columns of data. See SFrame.explore and SArray.explore.
show method displays a plot of the requested data structure or pair of
data structures to the user, with an automatically selected plot type. When in
Jupyter Notebook, it outputs to the notebook by default, and otherwise opens a
native window. This behavior can be controlled with
Visualizations produced by
show mostly involve aggregated data. Some examples
of aggregation used in Turi Create visualization include
histogram binning, used in the
histogram and heat map plots, and
count distinct, used in
the summary statistics in
SFrame.show. These aggregations can take a long
time to perform on a large dataset.
To enable you to see the plot immediately, Turi Create runs these aggregators in a streaming fashion, operating on small batches of data and updating the plot when each batch is complete. This helps you make decisions about what to do next, by giving you an immediate (but partial) view of the dataset, rather than waiting until the aggregation is complete.
While aggregation is happening, a green progress bar is shown at the top of the plot area (see screenshot below). The progress bar will disappear once aggregation has finished.
show method on
SArray produces a summary of the data in the SArray. For
numeric data (
float), this shows a numeric
histogram of the data.
For categorical data (
str), this shows a
representing the counts of frequently occurring items, sorted by count. The
show method on SFrame produces a summary of each column of the SFrame, using
the plot types described for
In addition to the
show method available on individual data structures, the
turicreate.show method takes two parameters (
y) to plot two data
structures, one on each dimension. The
y parameters must both be
SArrays of the same length. The specific plot type shown depends on the
y as follows:
- If both
yare numeric, and larger than 5,000 rows, a numeric heat map is shown.
yare numeric, and smaller than or equal to 5,000 rows, a scatter plot is shown.
- If one is numeric and the other is categorical, a box plot is shown.
- If both are categorical, a categorical (discrete) heat map is shown.
In order to stream plots on very large datasets, we use some highly accurate approximate aggregators from Sketch:
- Counts shown in the plot for categorical item frequency in
- All numeric values in Box Plots use
All other values shown in Turi Create visualizations are calculated exactly.
show methods have optional parameters for specifying some plot
title=sets the title of the plot for
turicreate.show, or the title of the exploration UI for
xlabel=sets the label of the X axis for
ylabel=sets the label of the Y axis for
These customizations are especially useful when arranging several visualization windows side-by-side for comparison.
Visualizations produced with
show allow you to save the rendered plot image
Save... produces a
.png file) or
Save Vega... produces a
.json file). An image representation will allow
you to share, publish, or view the rendered plot, while the Vega specification
allows for customization of the rendered plot using a variety of tools that
support Vega specifications, like the
You can find these options in the
File menu as shown below:
Turi Create also lets you save plots as PNG, SVG, or JSON as part of the
Python Plot API. You can save a Plot object by invoking the
save method, as
shown in the example below:
import turicreate as tc # build the plot x = tc.SArray([1,2,3,4,5]) y = x * 2 custom_plot = tc.visualization.scatter(x,y) # save the plot custom_plot.save("custom.json") custom_plot.save("custom.png") custom_plot.save("custom.svg")
explore method allows for interactive exploration of the dataset,
including raw (non-aggregated) data. This takes the form of a
scrollable table capable of showing all rows and columns from the dataset:
show, the result of
explore cannot be saved to
.png or exported as
a Vega specification.
To see examples of all the possible visualizations you can get from Turi Create, see the gallery. For a walk-through of when and why to use visualization in the process of feature engineering, see sample use cases. For specific methods and their API parameters, see: