Ideas

• Handle negatives
• Think about filtering
  • allow predicates to filter/reject
  • sampling? there's a lodash function for that.

Names

• File names should be more consistent.
• TextBox could be renamed to App?

React

• ref usage can be improved. For example,ref={r => this.input = r}. See: https://facebook.github.io/react/docs/more-about-refs.html
• Constructors should chain to super.

Code

• Merge variants of TextBox::handle@Submit into a single function?
• Redundancies in renderUI can be eliminated, e.g. introduce a Parameter component.
• x => f(x) can be simplified into f (except for when this is involved).
• JSON.stringify can be used in place of objectString.
• The accessor methods can have better names. lFunc => label

Style

• Dangling } looks bad

BarGraph

• The instance variables look out of place.
• Might be interesting to share the similar parts with LinePlot and extra into a helper class. Perhaps Data (with methods to calculate, etc)?
• renderTopLine - identify similar expressions and abstract by introducing methods.
• Look into using fold or reduce.