Find break points in a curve

Question

I have a set of data (less than 6kB) that has a breaking point when plotted (for example, using ListPlot).

testbreak = ToExpression /@ Import["~\\test_break_curve.csv"];
plt = ListPlot[testbreak, PlotRange -> {{0, 4}, All}, Frame -> True]

I want to find the coordinates of the breaking point(s) so that I can plot it with ListLinePlot as two segments of continuous curves (in solid lines) instead of points. In other words, I don't want the part in the black box but need the coordinates of the two points in the circles. The following figure is plotted with ListLinePlot. Is there a method to do this? Thank you in advance!

Answer 1

Choice of transition step as 0.1 is arbitrary.

blist = testbreak[[All, 2]] // Differences;
pos = Position[blist, _?(Abs@# > 0.1 &)]

{{122}}

Coordinates for the transition

excl = testbreak[[{122, 123}]]

{{2.425, -0.584512}, {2.445, -1.09194}}

TakeDrop[testbreak, Det@pos] //
 ListLinePlot[#
   , PlotStyle -> Thick
   , Epilog -> {Dashed, Red, Line@excl}
   ] &

Answer 2

We split the points of sequence by the Max difference quotient.

index=Ordering[
 Abs[(Last[#2] - Last[#1])/(First[#2] - First[#1])] & @@@ 
  Partition[testbreak, 2, 1], -1]//First

122

pts = TakeList[testbreak, {index - 1, 2, All}];
pts[[2]]
ListPlot[pts, PlotStyle -> {Blue, Dashed, Green}, Joined -> True]

Answer 3

Using Split:

ListLinePlot[
 Split[
  testbreak,
  Abs[#[[2]] - #2[[2]]] < 0.1 &
  ]
 ]