<div dir="ltr">Hi Sri,<div>I see a couple of things in your script that you should check:</div><div><br></div><div>1 - You have the following:</div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">do ne=0,neof-1</span><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"> eof_regres(ne,:,:)= regCoef(eof_ts(ne,:), t2mw(lat|:,lon|:,time|:));</span><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">end do</span><br></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">...</span></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">df = onedtond(eof_regres@nptxy,</span><wbr style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">dimsizes(eof_regres))-2 ; degrees of freedom</span><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">tval = onedtond(eof_regres@tval, dimsizes(eof_regres)) ; t-statistic</span><br></span></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></span></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Note that the @tval and @nptxy attributes get overwritten each time through the do loop. If neof = 1, the above will work, otherwise the coding should be changed.</span></span></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></span></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">2 - With regards to this error message:</span></span></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">warning:VarVarWrite: rhs has no dimension name or coordinate variable, deleting name of lhs dimension number (1) and destroying coordinate var, use "(/../)" if this is not desired outcome</span><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">warning:VarVarWrite: rhs has no dimension name or coordinate variable, deleting name of lhs dimension number (2) and destroying coordinate var, use "(/../)" if this is not desired outcome</span><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">warning:["Execute.c":8640]:</span><wbr style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Execute: Error occurred at or near line 135 in file NAOregreT2M_obs.ncl</span></span></span></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></span></div><div><span style="font-size:12.8px">I do not know what line 135 is, but the error message above is telling you how to fix it. The error message is generated because the metadata on the left hand side of the equal sign is getting overwritten by the metadata on the right hand side of the equal sign. Note: This error message does not mean that your calculation of the significance of your trend is incorrect. However, I do not see where you are calculating a trend, as you are seemingly regressing a EOF principal component timeseries on a time x lat x lon array. </span></div><div><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px">Here is some code that I use to calculate the significance of trends (using the betainc function as you were doing):</span></div><div><span style="font-size:12.8px"><br></span></div><div><div><span style="font-size:12.8px">tarr = obs_ann(:,:,5::12)</span></div><div><span style="font-size:12.8px">tttt = dtrend_msg(ispan(0,dimsizes(tarr&time)-1,1),tarr,True,True) </span></div><div><span style="font-size:12.8px">finobs = tarr(0,:,:)</span></div><div><span style="font-size:12.8px">finobs_rtt = finobs</span></div><div><span style="font-size:12.8px">finobs = (/ onedtond(tttt@slope, (/dimsizes(obs_seas&lat),dimsizes(obs_seas&lon)/) ) /)</span></div><div><span style="font-size:12.8px"> </span></div><div><span style="font-size:12.8px">tval = tarr(:,:,0)</span></div><div><span style="font-size:12.8px">df = new((/dimsizes(tarr&lat),dimsizes(tarr&lon)/),"integer")</span></div><div><span style="font-size:12.8px">rc = regcoef(ispan(0,dimsizes(tarr&time)-1,1),tarr,tval,df) </span></div><div><span style="font-size:12.8px">df = equiv_sample_size(tarr,0.05,0) ; Optional! over rule df returned from regcoef. U<span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">p to you whether you want to use equiv_sample_size or not</span></span></div><div><span style="font-size:12.8px">df = df-2<span style="white-space:pre"> </span>;regcoef/equiv_sample_size return N, need N-2</span></div><div><span style="font-size:12.8px">beta_b = tval</span></div><div><span style="font-size:12.8px">beta_b = 0.5</span></div><div><span style="font-size:12.8px">finobs_rtt = (/ (1.-betainc(df/(df+tval^2), df/2.0, beta_b))*100. /) ; probability in %</span></div><div><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px">Hope that helps. If you have any further queries please respond to ncl-talk.</span></div><div><span style="font-size:12.8px">Adam</span></div><div><br></div></div><div><span style="font-size:12.8px"><br></span></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 5, 2018 at 2:36 AM, Sri Nandini <span dir="ltr"><<a href="mailto:snandini@marum.de" target="_blank">snandini@marum.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Hello<br><br>I am trying to <span class="m_-1226483225063639934st"><em>calculate statistical significance</em> of a <em>linear</em> trend (Regression analysis).<br>The regression analysis simple enough.<br><br>I have troubles understanding how the probabilities are computed based on the trend i calculate?<br>What i actually wanted to do is calculate the 2 tailed ttest probabilities but it doesn't seem possible with NCL, unless someone else knows of a way?<br>Or does </span><span class="m_-1226483225063639934st"><em class="m_-1226483225063639934quotelev3">using the NCL function "betainc" to get the p-value
for a student test is the same thing?<br><br></em>
<em class="m_-1226483225063639934quotelev3">>>></em>My code is below:<br><br><br>f = addfile ("<a href="http://air.mon.mean.nc" target="_blank">air.mon.mean.nc</a>", "r")<br> latS = 29.3<br> latN = 67.26 <br> lonL = 19.<br> lonR = 60.<br><br> TIME1 = f->time<br> YYYY1 = cd_calendar(TIME1,-1)/100 <wbr> ; entire file<br> iYYYY1 = ind(YYYY1.ge.yrStrt .and. YYYY1.le.yrLast)<br> t2m = f->air(iYYYY1,:,:)<br> printVarSummary(t2m)<br><br> T2M = month_to_season (t2m, season)<br> printVarSummary(T2M)<br> nyrs = dimsizes(T2M&time)<br><br> t2mw = T2M({lat|latS:latN},{lon|lonL:<wbr>lonR},time|:)<br> printVarSummary(t2mw)<br><br> t2mw = dtrend(t2mw,False)<br> printVarSummary(t2mw)<br><br> eofT = eofunc_Wrap(t2mw, neof, optEOF)<br> printVarSummary(eofT)<br><br>;=============================<wbr>==============================<wbr>===============<br>eof_regres= eofT <wbr> ;create an array with meta data <br>do ne=0,neof-1<br>eof_regres(ne,:,:)= regCoef(eof_ts(ne,:), t2mw(lat|:,lon|:,time|:));<br> end do<br> printVarSummary(eof_regres)<br><br>;=============================<wbr>==============================<wbr>===============<br>;Calculate significance at 95% confidence<br>;The regCoef function returns the following attributes: yintercept (y-intercept), tval (t-statistic), rstd (standard error of the estimated regression coefficient) and nptxy (number of elements used). <br>;=============================<wbr>==============================<wbr>===============<br><br> df = onedtond(eof_regres@nptxy,<wbr>dimsizes(eof_regres))-2 ; degrees of freedom<br> tval = onedtond(eof_regres@tval, dimsizes(eof_regres)) ; t-statistic<br><br> b = tval <wbr> ; b must be same size as tval (and df)<br> b = 0.5<br> prob = betainc(df/(df+tval^2),df/2.0,<wbr>b)<br> printVarSummary(prob) <wbr> ; prob(nlat,nlon)<br><br> ;copy_VarCoords(eof_regres,<wbr>prob)<br> prob@long_name = "probability"<br> ;prob@units = "fraction: [0,1]"<br><br> prob_95=where (prob.ge.0.95,1,0) ; **** note 0.95 ****<br> copy_VarCoords(prob, prob_95)<br> printVarSummary(prob_95) <br><br> eof_regres@long_name = "regression coefficient"<br> prob@long_name = "probability"<br> <br>;=============================<wbr>=====The error message i get is:<br><br>warning:VarVarWrite: rhs has no dimension name or coordinate variable, deleting name of lhs dimension number (1) and destroying coordinate var, use "(/../)" if this is not desired outcome<br>warning:VarVarWrite: rhs has no dimension name or coordinate variable, deleting name of lhs dimension number (2) and destroying coordinate var, use "(/../)" if this is not desired outcome<br>warning:["Execute.c":8640]:<wbr>Execute: Error occurred at or near line 135 in file NAOregreT2M_obs.ncl<br><br><br>Variable: eof_regres<br>Type: float<br>Total Size: 49856 bytes<br> 12464 values<br>Number of Dimensions: 3<br>Dimensions and sizes: [evn | 2] x [76] x [82]<br>Coordinates: <br> evn: [1..2]<br>Number Of Attributes: 11<br> tval : <ARRAY of 6232 elements><br> yintercept : <ARRAY of 6232 elements><br> rstd : <ARRAY of 6232 elements><br> nptxy : <ARRAY of 6232 elements><br> long_name : EOF: DJF: Monthly mean of surface temperature<br> _FillValue : -9.96921e+36<br> method : transpose<br> matrix : covariance<br> pcvar : ( 59.16475, 20.32462 )<br> eval : ( 18982.65, 6521.03 )<br> eval_transpose : ( 169.488, 58.22348 )<br><br><br></span></div>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div><div><span><font color="#888888">Adam Phillips <br></font></span></div><span><font color="#888888">Associate Scientist, </font></span><span><font color="#888888">Climate and Global Dynamics Laboratory, NCAR<br></font></span></div></div><div><span><font color="#888888"><a href="http://www.cgd.ucar.edu/staff/asphilli/" target="_blank">www.cgd.ucar.edu/staff/asphilli/</a> </font></span><span><font color="#888888">303-497-1726 </font></span></div><span><font color="#888888"></font></span><div><div><span><font color="#888888"><br></font></span><div><span><font color="#888888"><a href="http://www.cgd.ucar.edu/staff/asphilli" target="_blank"></a></font></span></div></div></div></div></div></div></div></div></div></div></div>
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