scipy - Trying to interpolate linearly in python -


i have 3 arrays: a, b, c length 15. 

a=[950, 850, 750, 675, 600, 525, 460, 400, 350, 300, 250, 225, 200, 175, 150]   b = [16, 12, 9, -35, -40, -40, -40, -45, -50, -55, -60, -65, -70, -75, -80]  c=[32.0, 22.2, 12.399999999999999, 2.599999999999998, -7.200000000000003, -17.0, -26.800000000000004, -36.60000000000001, -46.400000000000006, -56.2, -66.0, -75.80000000000001, -85.60000000000001, -95.4, -105.20000000000002]

i trying find value of @ index b=c. t

the problem there no place b=c need linearly interpolate between values in array find value of b=c. make sense?

i thinking using scipy.interpolate interpolation.

i having hard time wrappying mind around how solve problem. ideas on great!

here's simpler variation of function another answer of mine:

from __future__ import division  import numpy np   def find_roots(t, y):     """     given input signal `y` samples @ times `t`,     find times `y` 0.      `t` , `y` must 1-d numpy arrays.      linear interpolation used estimate time `t` between     samples @ sign changes in `y` occur.     """     # find y crosses 0.     transition_indices = np.where(np.sign(y[1:]) != np.sign(y[:-1]))[0]      # linearly interpolate time values transition occurs.     t0 = t[transition_indices]     t1 = t[transition_indices + 1]     y0 = y[transition_indices]     y1 = y[transition_indices + 1]     slope = (y1 - y0) / (t1 - t0)     transition_times = t0 - y0/slope      return transition_times

that function can used t = a , y = b - c. example, here data, entered numpy arrays:

in [354]: = np.array([950, 850, 750, 675, 600, 525, 460, 400, 350, 300, 250, 225, 200, 175, 150])  in [355]: b = np.array([16, 12, 9, -35, -40, -40, -40, -45, -50, -55, -60, -65, -70, -75, -80])  in [356]: c = np.array([32.0, 22.2, 12.399999999999999, 2.599999999999998, -7.200000000000003, -17.0, -26.800000000000004, -3      ...: 6.60000000000001, -46.400000000000006, -56.2, -66.0, -75.80000000000001, -85.60000000000001, -95.4, -105.2000000000      ...: 0002])

the place "b = c" place "b - c = 0", pass b - c y:

in [357]: find_roots(a, b - c) out[357]: array([ 312.5])

so linearly interpolated value of a 312.5.

with following matplotlib commands:

in [391]: plot(a, b, label="b") out[391]: [<matplotlib.lines.line2d @ 0x11eac8780>]  in [392]: plot(a, c, label="c") out[392]: [<matplotlib.lines.line2d @ 0x11f23aef0>]  in [393]: roots = find_roots(a, b - c)  in [394]: [axvline(root, color='k', alpha=0.2) root in roots] out[394]: [<matplotlib.lines.line2d @ 0x11f258208>]  in [395]: grid()  in [396]: legend(loc="best") out[396]: <matplotlib.legend.legend @ 0x11f260ba8>  in [397]: xlabel("a") out[397]: <matplotlib.text.text @ 0x11e71c470>

i plot

plot


-

Comments

Post a Comment

Popular posts from this blog

javascript - Thinglink image not visible until browser resize -

Image
i trying repurpose pre-existing theme, includes drop down menu displays image. trying embed thinglink drop down menu's content section, not visible until resize browser window. here menu looks like: then when clicked, can see empty space image should show: then when browser resized, image appears: this code content of menu: <div class="ajax_accordion_content" style="display: none;"> <div class="report-detail"> <table border="0" cellpadding="0" cellspacing="0" width="100%" class="table_basic"> <tbody> <!-- thinglink image embedded --> <img style="max-width: 100%;" src="http://cdn.thinglink.me/api/image/832705713204625409/1024/10/scaletowidth#tl-832705713204625409;1043138249'" class="alwaysthinglink"/> <script async charset="utf-8" src="http://cdn.thinglink.me/jse/embed.j...
Read more

firebird - Error "invalid transaction handle (expecting explicit transaction start)" executing script from Delphi -

i'm developing update app delphi 10. i'm running windows 7 64x, firebird 2.5.1.26351 32x. execution order: checks current version(select statement firebird database) downloads update(via ftp) apply it(.exe files, , execute .sql) error code -901 pops out when try execute .sql files. know there incompatibility issue w7 64x , fdb 32x, but, can everything: backup , restore(gbak), db commands(all). tried fdb 64x instead, , not working. code: //components fdwaitcursor: tfdguixwaitcursor; fddriverlink: tfdphysfbdriverlink; fdconnection:tfdconnection; fdscript: tfdscript; function tthr_script.createcomponents:boolean; begin try fddriverlink := tfdphysfbdriverlink.create(fddriverlink); fdwaitcursor := tfdguixwaitcursor.create(fdwaitcursor); fdconnection := tfdconnection.create(fdconnection); fdconnection begin drivername := 'fb'; params.username := thrbanco.bduser; params.password := thrbanco.bdpass; params.database := ...
Read more

Sound is not coming out while implementing Text-to-speech in Android activity -

i using texttospeak in 1 of app. while adding speech string texttospeech object instance, doesn't produce sound. though not getting error in log still sound not coming out. want device speak value of textview gets set resultmsg.settext() method. public class resultactivity extends activity { @override protected void oncreate(bundle savedinstancestate){ ............ resultmsg.settext(resultmsg_str); texttospeech = new texttospeech(getapplicationcontext(),newtexttospeech.oninitlistener(){ @override public void oninit(int status) { system.out.println("txt speech status = "+status); system.out.println("txt speech error status = "+texttospeech.error); system.out.println("txt speech success status = "+texttospeech.success); if(status == texttospeech.success){ texttospeech.setlanguage(locale.english); ...
Read more