​​​​​Creating a graph with shared areas that cover positive and negative numbers in the y-axis

[Mayra Pineda]

Hello,

I created a graph that includes markers for each one of the data points and shaded areas for periods. The chart looks fine when the plotted variable takes positive values. However, when it takes negative values, the shared areas are not shown for any negative value; they are just shown from zero to any positive value.

The following is the code I am using:

preserve
    collapse var, by(group year)
    bysort group : gen first = _n == 1
    expand 2 if first, gen(newvar)
    replace year = 2008 if newvar == 1
    replace var = . if newvar == 1
    sort group year
    drop first newvar
    set scheme s1color
    separate var, by(group) veryshortlabel
    twoway scatteri -3 2002.5 1 2002.5 1 2005.5 -3 2005.5, recast(area) color(red*0.2) || ///
    scatteri -3 2005.5 1 2005.5 1 2007.5 -3 2007.5, recast(area) color(red*0.3) || ///
    scatter var? year, ms(dh oh) legend(lab(3 "A") lab(4 "B") order(4 3) position(6) col(1)) yscale(r(-3 1)) ylabel(-3(.5)1) xlabel(2000(1)2007)
restore

An example of the dataset I am using is:

* Example generated by -dataex-. To install: ssc install dataex
clear
input float(individual year group var)
 1 2000 1  -1.287641
 1 2001 1  -.8836126
 1 2002 1 -1.1622982
 1 2003 1  -1.082307
 1 2004 1 -1.1710584
 1 2005 1 -1.1796787
 1 2006 1 -1.2466114
 1 2007 1 -1.1606842
 2 2000 1 -.15043515
 2 2001 1  -.2209688
 2 2002 1 -.19620353
 2 2003 1  -.3402078
 2 2004 1  -.4571495
 2 2005 1  -.4485733
 2 2006 1 -.50437814
 2 2007 1  -.4616068
 3 2000 1  -.8550537
 3 2001 1  -.8602186
 3 2002 1  -.8605418
 3 2003 1  -.8876227
 3 2004 1  -.9352865
 3 2005 1 -1.0311842
 3 2006 1 -1.0150617
 3 2007 1 -1.0626712
 4 2000 1 -1.5768597
 4 2001 1 -1.4882183
 4 2002 1  -1.474381
 4 2003 1  -1.541484
 4 2004 1  -1.532406
 4 2005 1 -1.5681677
 4 2006 1 -1.4693305
 4 2007 1 -1.1766837
 5 2000 1  -.9059771
 5 2001 1  -.9684552
 5 2002 1 -1.0976796
 5 2003 1   -.921452
 5 2004 1  -.9920011
 5 2005 1  -1.285856
 5 2006 1 -1.2974216
 5 2007 1   -1.80346
 6 2000 1   .3173624
 6 2001 1  .25653982
 6 2002 1  .14316559
 6 2003 1  .13082898
 6 2004 1  .08094823
 6 2005 1 -.05380845
 6 2006 1  -.1298359
 6 2007 1    -.43694
 7 2000 1  -.8702447
 7 2001 1 -1.0644857
 7 2002 1 -1.0852207
 7 2003 1 -1.2581582
 7 2004 1 -1.1840831
 7 2005 1  -1.003717
 7 2006 1   -.875128
 7 2007 1  -.9327229
 8 2000 1 -1.3506677
 8 2001 1  -1.451754
 8 2002 1  -1.716019
 8 2003 1 -1.9588758
 8 2004 1 -2.0517306
 8 2005 1  -2.854429
 8 2006 1  -2.816115
 8 2007 1   -1.93434
 9 2000 1  -.4100389
 9 2001 1   -.435545
 9 2002 1 -.49928665
 9 2003 1  -.5177228
 9 2004 1   -.534188
 9 2005 1 -.58403265
 9 2006 1  -.6003072
 9 2007 1  -.5960971
10 2000 0 -1.4216475
10 2001 0 -1.4646496
10 2002 0  -1.521221
10 2003 0  -1.599065
10 2004 0  -1.688853
10 2005 0  -1.668002
10 2006 0 -1.1764842
10 2007 0  -1.364062
end

I appreciate any help you could provide.

Thanks,

Mayra

[William Lisowski]

I think replacing the first two lines of your twoway command

    twoway scatteri -3 2002.5 1 2002.5 1 2005.5 -3 2005.5, recast(area) color(red*0.2) || ///
    scatteri -3 2005.5 1 2005.5 1 2007.5 -3 2007.5, recast(area) color(red*0.3) || ///

with

    twoway scatteri -3 2002.5 1 2002.5 1 2005.5 -3 2005.5, recast(area) nodropbase color(red*0.2) || ///
    scatteri -3 2005.5 1 2005.5 1 2007.5 -3 2007.5, recast(area) nodropbase color(red*0.3) || ///

will accomplish what you want. Experts on Stata Graphics may be able to tell us a better way of shading rectangular areas on a plot.

[Mayra Pineda]

It worked! Thanks, William!