plot x+3 , x**2+5*x+12
Is it possible to set x+3 to have only 2 samples and x**2+5*x+12 to have say 1000 samples in the same plot?
It can be done, but not out-of-the-box.
The first variant uses a temporary file to save one function with a low sampling rate and plotting it later together with the high-resolution function:
set samples 2
set table 'tmp.dat'
plot x+3
unset table
set samples 1000
plot 'tmp.dat' w lp t 'x+3', x**2 + 5*x + 12
This has the advantage, that you can use any sampling rates for both functions.
For you special case of 2 samples for one function, it can be done without an external file, but it involves quite some tricking:
set xrange [-10:10]
s = 1000
set samples s
f1(x) = x + 3
set style func linespoints
set style data linespoints
plot '+' using (x0 = (($0 == 0 || $0 == (s-1) )? $1 : x0), \
($0 < (s-2) ? 1/0 : x0)):(f1(x0)) t 'x+3',\
x**2 + 5*x + 12
What I did here is:
Use the special filename + to generate a set of coordinates in the current xrange. This must be set, no autoscaling is possible.
Skipping all points but the first and the last by giving them the value 1/0 doesn't work, because the two remaining points aren't connected.
So I store the first x-value (when $0, or column(0) equals 0) and use it when I encountered the second last points. For the last points, the usual values are used.
That works for your special case of 2 samples.
You must keep in mind, that the first function is treated as data, so you must use both set style data and set style func (just to show it).
The result with 4.6.4 is:
I am not sure if different samplings (as opposed to different ranges) are possible with gnuplot 5.x. If I missed that please let me know.
Here is a suggestion to have two different samplings in the same plot command without temporary files (or datablocks from gnuplot 5.0 on).
A requirement is a known xrange, i.e. it will work with autoscale only if you plot and replot the graph to automatically get xmin and xmax. For the second function you could also use '+' u 1:(f2($1)) w lp.
Script: (works for gnuplot>=4.4.0, March 2010)
### different samplings in one plot command
reset
set xrange[xmin=-10:xmax=10]
f1(x) = x+3
f2(x) = x**2 + 5*x + 12
s1 = 3 # sampling 1
s2 = 101 # sampling 2
set samples (s1>s2?s1:s2) # the higher value
dx1 = real(xmax-xmin)/(s1-1) # determine dx1 for f1
plot '+' u (x0=xmin+$0*dx1):(f1(x0)) every ::0::s1-1 w lp pt 7 ti sprintf("%d samples",s1), \
f2(x) w lp pt 7 ti sprintf("%d samples",s2)
### end of script
Result:
Related
I have a text file with 3 columns defining 3D points.
I want to paint every point in 3D and an ellipsoid centered in every point. I discard using the
set parametric
way because I need to iterate my text file.
So i think in doing something like this:
gnuplot
reset
set xrange [-5:5]
set yrange [-5:5]
set zrange [-5:5]
Rx = 1
Ry = 1
Rz = 1
fx(u,v) = column(2) + Rx*cos(u)*cos(v)
fy(u,v) = column(1) + Ry*sin(u)*cos(v)
fz(u,v) = column(3) + Rz*sin(v)
iMax = 200
splot "file.txt" using ($2):($1):($3) title "Input " with points ps 2 pt 7,\
for [i=0:iMax] "file.txt" u (fx(2*pi*i/iMax, pi*i/iMax)):(fy(2*pi*i/iMax, pi*i/iMax)):(fz(2*pi*i/iMax, pi*i/iMax)) notitle with points ps 2 pt 7
But the only think I can get is this strange and heavy (I know that they are a lot of iterations per row, but maybe there is another approach) pattern
Any help? Thank you.
There is something wrong for the mathematic point of view? Using something like this Im perfectly able to plot spheres, but without parsing data:
set parametric
R = 1
set urange [-pi/2:pi/2]
set vrange [0:2*pi]
splot R*cos(u)*cos(v),R*cos(u)*sin(v),R*sin(u) w l lc rgb "yellow"
I assume you want to plot the 2D surfaces of 3D ellipsoids. But the plot command has only a loop over i which is only 1D. This can not give a 2D surface. It might be possible to nest another 1D loop to get this approach to work.
I would suggest something else. Before plotting, you can store the center coordinates into a gnuplot array. Then you loop over this array and plot a sphere/ellipsoid using parametric mode.
This might be a starting point:
# This is the file with the center coordinates.
datafile = "ellipses.dat"
# The "stats" command stores the number of rows in the STATS_records variable.
stats datafile nooutput
num_rows = STATS_records
# Generate arrays which will contain the center coordinates of the ellipsoids.
array centers_x[num_rows]
array centers_y[num_rows]
array centers_z[num_rows]
# Read the center coordinates into the prepared arrays.
# I "misuse" the stats command. The "using" expression in parenthesis executes
# the respective commands and returns the value after the last comma: row + 1.
# This return value is not needed anywhere.
row = 1
stats datafile using (centers_x[row]=$1, \
centers_y[row]=$2, \
centers_z[row]=$3, \
row = row + 1) nooutput
# Output into an image file.
set terminal pngcairo
set output "ellipsoids.png"
# Set parameters for ellipsoids.
Rx = 0.1
Ry = 0.1
Rz = 0.7
# Use parametric mode for plotting.
set parametric
set urange [-pi/2:pi/2]
set vrange [0:2*pi]
# Finally plot:
splot datafile using 1:2:3 title "Input " with points ps 2 pt 7, \
for [i=1:num_rows] centers_x[i] + Rx*cos(u)*cos(v), \
centers_y[i] + Ry*cos(u)*sin(v), \
centers_z[i] + Rz*sin(u) notitle
Please doublecheck x, y, and z: I was not that careful. This is the result:
I have used this example data:
1 2 3
2 2 4
2 3 4
3 3 3
3 4 5
Arrays are available starting with gnuplot 5.2. For older versions, please search the internet for workarounds.
[Current]
I am importing a text file in which the first column has simulation time (0~150) the second column has the delay (0.01~0.02).
1.000000 0.010007
1.000000 0.010010
2.000000 0.010013
2.000000 0.010016
.
.
.
149.000000 0.010045
149.000000 0.010048
150.000000 0.010052
150.000000 0.010055
which gives me the plot:
[Desired]
I need to plot an average line on it like shown in the following image with red line:
Here is a gnuplot only solution with sample data:
set table "test.data"
set samples 1000
plot rand(0)+sin(x)
unset table
You should check the gnuplot demo page for a running average. I'm going to generalize this demo in terms of dynamically building the functions. This makes it much easier to change the number of points include in the average.
This is the script:
# number of points in moving average
n = 50
# initialize the variables
do for [i=1:n] {
eval(sprintf("back%d=0", i))
}
# build shift function (back_n = back_n-1, ..., back1=x)
shift = "("
do for [i=n:2:-1] {
shift = sprintf("%sback%d = back%d, ", shift, i, i-1)
}
shift = shift."back1 = x)"
# uncomment the next line for a check
# print shift
# build sum function (back1 + ... + backn)
sum = "(back1"
do for [i=2:n] {
sum = sprintf("%s+back%d", sum, i)
}
sum = sum.")"
# uncomment the next line for a check
# print sum
# define the functions like in the gnuplot demo
# use macro expansion for turning the strings into real functions
samples(x) = $0 > (n-1) ? n : ($0+1)
avg_n(x) = (shift_n(x), #sum/samples($0))
shift_n(x) = #shift
# the final plot command looks quite simple
set terminal pngcairo
set output "moving_average.png"
plot "test.data" using 1:2 w l notitle, \
"test.data" using 1:(avg_n($2)) w l lc rgb "red" lw 3 title "avg\\_".n
This is the result:
The average lags quite a bit behind the datapoints as expected from the algorithm. Maybe 50 points are too many. Alternatively, one could think about implementing a centered moving average, but this is beyond the scope of this question.
And, I also think that you are more flexible with an external program :)
Here's some replacement code for the top answer, which makes this also work for 1000+ points and much much faster. Only works in gnuplot 5.2 and later I guess
# number of points in moving average
n = 5000
array A[n]
samples(x) = $0 > (n-1) ? n : int($0+1)
mod(x) = int(x) % n
avg_n(x) = (A[mod($0)+1]=x, (sum [i=1:samples($0)] A[i]) / samples($0))
Edit
The updated question is about a moving average.
You can do this in a limited way with gnuplot alone, according to this demo.
But in my opinion, it would be more flexible to pre-process your data using a programming language like python or ruby and add an extra column for whatever kind of moving average you require.
The original answer is preserved below:
You can use fit. It seems you want to fit to a constant function. Like this:
f(x) = c
fit f(x) 'S1_delay_120_LT100_LU15_MU5.txt' using 1:2 every 5 via c
Then you can plot them both.
plot 'S1_delay_120_LT100_LU15_MU5.txt' using 1:2 every 5, \
f(x) with lines
Note that this is technique can be used with arbitrary functions, not just constant or lineair functions.
I wanted to comment on Franky_GT, but somehow stackoverflow didn't let me.
However, Franky_GT, your answer works great!
A note for people plotting .xvg files (e.g. after doing analysis of MD simulations), if you don't add the following line:
set datafile commentschars "##&"
Franky_GT's moving average code will result in this error:
unknown type in imag()
I hope this is of use to anyone.
For gnuplot >=5.2, probably the most efficient solution is using an array like #Franky_GT's solution.
However, it uses the pseudocolumn 0 (see help pseudocolumns). In case you have some empty lines in your data $0 will be reset to 0 which eventually might mess up your average.
This solution uses an index t to count up the datalines and a second array X[] in case a centered moving average is desired. Datapoints don't have to be equidistant in x.
At the beginning there will not be enough datapoints for a centered average of N points so for the x-value it will use every second point and the other will be NaN, that's why set datafile missing NaN is necessary to plot a connected line at the beginning.
Code:
### moving average over N points
reset session
# create some test data
set print $Data
y = 0
do for [i=1:5000] {
print sprintf("%g %g", i, y=y+rand(0)*2-1)
}
set print
# average over N values
N = 250
array Avg[N]
array X[N]
MovAvg(col) = (Avg[(t-1)%N+1]=column(col), n = t<N ? t : N, t=t+1, (sum [i=1:n] Avg[i])/n)
MovAvgCenterX(col) = (X[(t-1)%N+1]=column(col), n = t<N ? t%2 ? NaN : (t+1)/2 : ((t+1)-N/2)%N+1, n==n ? X[n] : NaN) # be aware: gnuplot does integer division here
set datafile missing NaN
plot $Data u 1:2 w l ti "Data", \
t=1 '' u 1:(MovAvg(2)) w l lc rgb "red" ti sprintf("Moving average over %d",N), \
t=1 '' u (MovAvgCenterX(1)):(MovAvg(2)) w l lw 2 lc rgb "green" ti sprintf("Moving average centered over %d",N)
### end of code
Result:
I have a data file example.dat with xy values, for example
0 10
1 40
5 20
How can I sample the linear interpolation of these points in gnuplot? I want to store that sampling in another file output.dat using set table. With cubic spline smoothing I can do
set table "output.dat"
set samples 10
plot "example.dat" smooth csplines
which yields an equidistant sampling of the cubic spline interpolation with 10 points. But I found no way to have such an equidistant sampling with linear interpolation: The sampling rate is just ignored (gnuplot 5.0).
I tried without any options and with linear interpolation "smoothing", like smooth unique, hoping that this would make gnuplot think of the dataset as a function which can be sampled, but to no avail.
My application is sampling different data files at a common grid for later comparison. I am aware that this is pushing the boundaries of what gnuplot is intended for, but since there is already a sampling mechanism I wonder if I am simply missing something.
In case this might still be of interest, the following is a "gnuplot only" solution. Not very elegant, but it seems to work.
### "gnuplot only" linear interpolation of data
reset session
$Data <<EOD
0 10
1 40
5 20
EOD
stats $Data u 1 nooutput
min = STATS_min
max = STATS_max
Samples=10
Interpolate(x0,y0,x1,y1,xi) = y0 + (y1-y0)/(x1-x0)*(xi-x0)
set print $Interpol
set table $Nowhere
do for [i=1:Samples] {
xi = min + (i-1)*(max-min)/(Samples-1)
do for [j=0:STATS_records-1] {
plot $Data u (a=$1,$1):(b=$2,$2) every ::j::j with table
plot $Data u (c=$1,$1):(d=$2,$2) every ::j+1::j+1 with table
if ( xi>=a && xi<=c) {
print sprintf("%g\t%g",xi,Interpolate(a,b,c,d,xi))
break
}
}
}
unset table
set print
set colorsequence classic
plot $Data u 1:2 w lp t "original data",\
$Data u 1:2 w lp smooth cspline t "smooth cspline",\
$Interpol u 1:2 w p pt 6 t "linear interpolation"
### end code
Hope I understood the question properly. You're having an equidistant sampling between 0 and 5, which in this case gives a step of 5/9=0.555556. To get a 0.5 distance between your samples, assuming your xrange[0:5], you should do set samples 11.
However, if you want to stick to 10 samples and all in steps of 0.5, you can tweak your xrange[0.5:5.0], which will create 9 steps of 0.5.
i'm having some problems with gnuplot
I have to draw a cdf function and i'm interested in the values of variable x when F(x) is equal to 0.1 and 0.9
How can I tell Gnuplot to show me on the x axis the value corresponding to a given value on the y value (in my example those values are 0.1 and 0.9)
thanks
You're basically asking gnuplot to solve an equation. In your particular case, actually two equations: F(x)=0.1 and F(x)=0.9. As far as I know this cannot be done, but I might be wrong. What you can do if you simply want a graphical solution, is make a conditional plot, and ask that when F(x) is very close to 0.1 0.9, gnuplot plots something other than the function.
For example, assume f(x)=x^2 and you want to know "graphically" for which x f(x)=0.1. Then you can request the value abs(f(x) - 0.1) be small, for example < 0.01. Then tell gnuplot to go to zero (just an example!) if this is the case, otherwise plot f(x)=x^2:
f(x)=x**2
set xrange [-2:2]
set samples 1000
plot abs(f(x)-1) < 0.01 ? 0 : f(x)
Which yields:
The two peaks that go to zero mark graphically on the x axis the solution to the equation f(x)=0.1. Of course, you need gnuplot to sample this point in order to see a peak. Thus you need to play with set samples and set xrange.
From your question it is not clear whether you have a function F(x) as expression or just a x,y-data file. I assume that your function is monotonic increasing in x and y.
Two solutions come to my mind:
via simple linear interpolation
via curve fitting
Let's create some test data. For this, let's assume your function is known (as expression) and something like this (check help norm): F(x) = a*norm(b*x + c)
Let's take a = 1; b = 0.8; c = -4. In the example below, sampling will be only 8, just for illustration purpose.
You can easily set samples 200 and you will get the same results as for the curve fitting method below. From gnuplot 5.0 on, you could write the data into a datablock instead of a file on disk.
Data: SO22276755.dat
0 3.16712e-05
1.42857 0.002137
2.85714 0.043238
4.28571 0.283855
5.71429 0.716145
7.14286 0.956762
8.57143 0.997863
10 0.999968
Script 1: (basically works for gnuplot 4.6.0, March 2012)
### interpolate x-values
reset
FILE = "SO22276755.dat"
yis = '0.10 0.90'
yi(n) = real(word(yis,n))
xis = ''
xi(n) = real(word(xis,n))
Interpolate(yi) = (x1-x0)/(y1-y0)*(yi-y0) + x0
getXis(xis) = xis.(n=words(xis), n<words(yis) ? yi=real(word(yis,n+1)) : 0, \
y0<=yi && y1>=yi ? sprintf(" %g",Interpolate(yi)) : '')
set key left top noautotitle
set grid x,y
plot x1=y1=NaN FILE u (x0=x1,x1=$1):(y0=y1,y1=$2,xis=getXis(xis),y1) \
w l lc rgb "blue" ti "data", \
'+' u (xi=xi(int($0+1))):(yi=yi(int($0+1))):\
(sprintf("(%.4g|%.4g)",xi,yi)) every ::0::1 \
w labels point pt 7 lc rgb "red" right offset -1,0 ti "interpolated"
### end of script
Result:
Script 2: (basically works for gnuplot>=4.6.0, March 2012)
With this approach you are fitting your known function F(x) to constant lines, i.e. your desired values 0.1 and 0.9. For this, a file will be created (could be a datablock for gnuplot>=5.0) and it will basically look like this SO22276755.fit:
0 0.1
1 0.1
0 0.9
1 0.9
### interpolate x-values
reset
F(x) = a*norm(b*x+c) # function
a = 1
b = 0.8
c = -4
yis = '0.10 0.90'
yi(n) = real(word(yis,n))
xis = ''
xi(n) = real(word(xis,n))
set key left top noautotitle
set grid x,y
# create fit levels file
LEVELS = "SO22276755.fit"
set table LEVELS
set samples 2
plot for [i=1:words(yis)] '+' u (yi(i))
unset table
xmin = 0
xmax = 10
set xrange[xmin:xmax]
set samples 100
xis = ''
do for [i=1:words(yis)] {
xi = (xmin+xmax)*0.5 # set start value
fit F(xi) LEVELS u 1:2 index i-1 via xi
xis = xis.sprintf(" %g",xi)
}
plot F(x) w l lc rgb "web-green" ti "F(x)", \
'+' u (xi=xi(int($0+1))):(yi=yi(int($0+1))):(sprintf("(%.4g|%.4g)",xi,yi)) \
every ::0::1 w labels point pt 7 lc rgb "red" righ offset -1,0 ti "fitted"
### end of script
Result:
I'm collecting pricing data on stocks and options during trading hours and appending them to a data file that I plot with gnuplot. The file looks like:
2013-01-30--15:58:14 38.68 0.64
2013-01-30--15:58:44 38.70 0.64
2013-01-30--15:59:15 38.70 0.64
2013-01-30--15:59:45 38.69 0.64
I end up with large periods of time that I don't collect any data for since the markets are closed.
When I plot this data with gnuplot, using xdata as timefmt, it displays large gaps from the end of one day to the start of another.
I'd prefer to have it skip those times during the days where there is no actual data... Is there a way to do this?
I've been able to come close by not plotting the data against the time value in the first column, but I'd like to show the time data AS WELL AS skip those times when the data was not collected.
I hope this makes sense and appreciate your help.
If I understood correctly, you can make good use of a broken axis on x.
There are two ways to obtain broken axis. The first one relies on ternary operators to plot the data only in the region of your interest, which in your case should not even be necessary, and shifting the xtics left in order to reduce the dimension of the empty region.
This is a nice tutorial:
http://gnuplot-tricks.blogspot.com/2009/06/broken-axis-revisited.html
The second one makes uses of multiplots instead. This is probably better suit to your needs.
http://gnuplot-tricks.blogspot.com/2010/06/broken-axis-once-more.html
Hope it helps.
There are similar but slightly different questions:
GNUPLOT Plotting 5 day financial week
I have non-contiguous date/time X data and want non-contiguous X scale
The question is not about breaking the axis, but skipping time intervals with no data.
This can simply be done by plotting the y-data versus the row index (i.e. pseudocolumn 0) (check pseudocolumns), however, then the challenge is to get some reasonable xtics. Here are two suggestions.
Script: (works for gnuplot>=5.0.0, Jan. 2015)
### skip non-trading hours
reset session
FILE = "SO14618708.dat"
myTimeFmt = "%Y-%m-%d--%H:%M:%S"
# create some random test data
set print FILE
t0 = time(0)
y0 = 100
do for [i=0:400] {
t = t0 + i*1800
isOpen(t) = tm_wday(t)>0 && tm_wday(t)<6 && tm_hour(t)>=9 && tm_hour(t)<=17
if (isOpen(t)) {
print sprintf("%s %g",strftime(myTimeFmt,t),y0=y0+rand(0)*2-1)
}
}
set print
set format x "%a\n%d" timedate
set grid x,y
set ytics 5
set key noautotitle
set multiplot layout 3,1
set title "with non-trading hours"
plot FILE u (timecolumn(1,myTimeFmt)):2 w l lc "red"
set title "without non-trading hours, but possible duplicates in day tics"
set format x "\n" timedate
myXtic(col) = strftime("%a\n%d",strptime(myTimeFmt,strcol(col)))
N = 15
plot FILE u 0:2 w l lc "web-green", \
'' u ($0*N):(NaN):xtic(myXtic(1)) every N
N = 1
set title sprintf("with tics only every Nth day (here: N=%d)",N)
SecPerDay = 3600*24
isNewDay(col) = (t0=t1,t1=timecolumn(col,myTimeFmt),t0!=t0 || int(t1)/SecPerDay-int(t0)/SecPerDay>0)
everyNthNewDay(col) = (isNewDay(col) ? d0=d0+1 : 0, d0==N ? (d0=0,1) : 0)
myXtic(col) = everyNthNewDay(col) ? strftime("%a\n%d",t1) : NaN
plot FILE u 0:2 w l lc "blue", \
t1=(d0=0,NaN) '' u 0:(NaN):xtic(myXtic(1))
unset multiplot
### end of script
Result:
Script: (version for the time of OP's question. Works for gnuplot>=4.6.0, March 2012)
Creation of reasonable time and string data files is difficult in gnuplot 4.6, so this part was skipped and assumed you have a suitable datafile.
Although, in the lowest plot, I've only managed either to not display the very first tic (Thu 22) or to show it incorrectly.
### skip non-trading hours
reset
FILE = "SO14618708.dat"
myTimeFmt = "%Y-%m-%d--%H:%M:%S"
set format x "%a\n%d"
set grid x,y
set ytics 5
set key noautotitle
set timefmt "%Y-%m-%d--%H:%M:%S"
set xdata time
set multiplot layout 3,1
set title "with non-trading hours"
plot FILE u (timecolumn(1)):2 w l lc rgb "red"
set title "without non-trading hours, but possible duplicates in day tics"
set format x "\n"
myXtic(col) = strftime("%a\n%d",strptime(myTimeFmt,strcol(col)))
N = 15
plot FILE u 0:2 w l lc rgb "web-green", \
'' u ($0*N):(NaN):xtic(myXtic(1)) every N
N = 1
set title sprintf("with tics only every Nth day (here: N=%d)",N)
SecPerDay = 3600*24
isNewDay(col) = (t0=t1,t1=strptime(myTimeFmt,strcol(col)),(t0!=t0) || ((int(t1)/SecPerDay-int(t0)/SecPerDay)>0))
everyNthNewDay(col) = (isNewDay(col) ? d0=d0+1 : 0, d0==N ? (d0=0,1) : 0)
myXtic(c) = c ? strftime("%a\n%d",t1) : ' '
plot FILE u 0:2 w l lc rgb "blue", \
t1=(d0=0,NaN) '' u ((c=everyNthNewDay(1)) ? $0 : NaN):(NaN):xtic(myXtic(c)) w p
unset multiplot
### end of script
Result: (created with gnuplot4.6.0)