I have a file called plot.txt with a number of values such as:
1 7.5000000000000000
2 10.312500000000000
3 11.660156250000000
4 12.425537109375000
5 12.913055419921875
6 13.248996734619141
7 13.493841290473938
8 13.679883163422346
9 13.825851876754314
10 13.943356417876203
This list continuous until about 450. When i try to plot it with lines i get a linear line across the graph. Why is this? line graph And how do I get rid of it?
open(newunit=write_unit,access='sequential',file='plotgnu.txt',status='unknown')
write(write_unit,*)'plot ''plot.txt'' with linespoints '
close(write_unit,status='keep')
!Kaller på gnuplot
call execute_command_line("gnuplot -persist plotgnu.txt")
When i plot it without linespoints I get the the correct graph just with points point graph
write(write_unit,*)'plot ''plot.txt'' '
Your data file contains the same data set four times without empty lines:
1 7.5000000000000000
2 10.312500000000000
...
437 14.999999999999998
438 14.999999999999998
1 7.5000000000000000
2 10.312500000000000
...
If you plot that with lines you do of course also get a line from the last point of the first "data set" to the first point of the second occurrence of the data set. And that is the line you are seeing.
Related
I have a matrix which contains the atom numbers of the pairs of atoms which are in contact with each other. My matrix is like this:
column 1: atom number i;
column 2: atom number j
i,j runs from 1 to 800.
If there is a pair i-j in the matrix, place a dot corresponding to the position (i,j) of the matrix.
How do I plot such matrix?
Example:
A= [1,3; 3,8; 3,1; 6,2; 2,6; 1,2; 5,2; 8,3; 2,5; 2,1]
I want to Plot the matrix A, where X and Y-axis run from 1 to 8. Place a dot for every combination of X and Y which are present in A.
I want a plot like this:
Isn't this just a scatter plot?
If your m x 2 matrix is saved in a text file then this is trivial.
Here are the contents of an example data file "input.dat":
4 3
3 4
5 3
3 5
8 2
2 8
All you need to do is open the data file in xmgrace using xmgrace input.dat.
Now, initially it will be a line plot, but if you do 'Plot' > 'Set Appearance' and then with the only set already being selected you can set the 'Symbol Properties' 'Type:' to Diamond and 'Line Properties' 'Type:' to None you will already be on your way. Setting the symbol fill to solid red, tweaking the axis ranges and showing major tick grid lines will give a plot like the one you gave as an example.
You can save a parameters file and in future load the parameters at the beginning using
xmgrace -param template.par input2.dat.
But, having said all this, why not just plot it in matlab?
I have a data file consisting of two blocks (separated by a single blank line) and would like to plot the difference between data from block 1 and block 2, i.e., something like
plot 'a.dat' using 1:($2_1-$2_2)
where $2_1 is supposed to mean "data from block 1, col.2" and $2_2 "data from block 2, col.2". Is that possible within Gnuplot, and if so, how?
Thanks,
Tom
This task is most likely not possible directly in Gnuplot, however, one can preprocess the data file first, using, e.g., gawk and then plot the modified file. For example:
dataFile="a.dat"
plotCmd(fname)=sprintf("<gawk '\
BEGIN{mode=0;l=0;} \
mode==0{if(NF==0){mode=1;}else{x[NR]=$1;y[NR]=$2;}} \
mode==1{if(NF>0){mode=2;l=NR;}} \
mode==2{print $1,y[NR-l+1],$2}' %s", fname)
plot plotCmd(dataFile) u 1:($2-$3) w l
The gawk script reads the file and saves the first and second column into arrays x and y until it reaches a blank line (zero number of fields). Then it skips all consecutive blank lines until it reaches a non-empty line (NF>0). It remembers the position of this line in the input file and then outputs for each line in the second block the x-coordinate together with the corresponding y-coordinate from the first block, i.e., a data file such as
1 2
2 4
3 6
1 4
2 8
3 12
would be transformed into
1 2 4
2 4 8
3 6 12
This assumes that the x-coordinates in both blocks match...
I have a file with a matrix like :
1 2 3
4 5 6
7 8 9
Using gnuplot, I would like to extract the Variable in the 3th row on the 2th column, and store it in a variable called X for example. please how to do that using gnuplot.
Thanks
You can do that within a plot command,
set table "/dev/null"
X=0
X_row=3
X_col=2
plot "file.dat" using (($0==X_row)?(X=column(X_col),X):0)
unset table
To save time the plot command can do something useful at the same time, like... plotting something.
Thanks, It's solved actually using this syntax :
plot u 0:($0==RowIndex?(VariableName=$ColumnIndex):$ColumnIndex)
#RowIndex starts with 0, ColumnIndex starts with 1
print VariableName
It's already explained quite well here :
by #StackJack
I have some values given by clock time, where the first column is the time. However, the values until 2 o clock still belong to the current day. Given
3 1
12 4
18 1
21 2
1 3
2 0
named as test.data, I'd like to print this in gnuplot:
set xrange [0:24]
plot 'test.data' with lines
However, the plot contains a backward line. It's striking through the whole diagram.
Is there a way to tell gnuplot to explicitly not print such backward lines, or even better, print them wrapping around the x axis (e.g. in my example drawing the line as a forward line up to 24, and then continuing it at 0)?
Note: The x axis of the plot should still start at 0 and end at 24.
As far as wrapping over the edge of the graph (a pac-man like effect), gnuplot can't do that on it's own. Even doing it manually, you would have to somehow calculate the right point to re-enter the graph based on the slope of the connecting line, and insert a new point into the data to control where the re-entry line enters, and where the exiting line exits. This would require external processing.
If you can do some outside preprocessing, adding a blank line before the 1 3 line will insert a discontinuity into the plot and prevent gnuplot from connecting those points (see help datafile for how gnuplot handles blank lines). Of course, you could always sort the data too.
I would recommend sorting the data before plotting, but if you do want to do this wrapping effect, the following python program (wrapper.py) will set up the data for it
data = [tuple(map(float,x.strip().split(" "))) for x in open("data.txt","r")]
data2 = sorted(data)
back_in_to = data2[0]
out_from = data2[-1]
xdelta = back_in_to[0] + 24 - out_from[0]
ydelta = back_in_to[1] - out_from[1]
slope = ydelta/xdelta
outy = out_from[1] + (24-out_from[0])*slope
print(0,outy)
for x in data2:
print(*x)
if x[0]==data[-1][0]: print("")
print(24,outy)
It reads in the data (assumed to be in data.txt, and calculates the points where a line should leave the graph and where it should re-enter, adding these points to the sorted data. It adds a blank line after the last point in the original graph, causing the break in the line. We can then plot like
plot "< wrapper.py" with lines
If we look at your original plot
we see the backward line that you referred to which reaches from the furthest right point to the next left point. The plot that the python program pre-processed reaches through the right of the graph to move back to this point.
According to figure above. this picture is generated from data points in text file. My question is that how can i remove the line at any two points if graph is jumped? (In my picture see that graph is jump about on x~260)
note that my purpose is that i just want to make this graph look like piecewise function that mean line on the middle of graph should not be connected because is jumped.
In gnuplot you can split a line in several parts either when you have an invalid data value somewhere, or an empty line.
For the first situation, you could check inside the using statement, if the difference to the previous point is too large, and invalidate the current point. But that would also make you loose not only the connecting line, but also the first point after the jump:
lim=3
y2=y1=0
plot 'test.dat' using (y2=y1,y1=$2,$1):($0 > 0 && abs(y2-y1) > lim ? 1/0 : y1) with linespoints
The test data file I used is
1 1
2 1.1
3 0.95
4 1
5 5
6 6
7 5.5
8 5.8
9 -2
10 -2.5
11 -4
As you see, the points at x=5 and x=9 are lost.
Alternatively, you can pipe your data through an external tool like awk for the filtering. In this case you can insert an empty line when the difference between two consecutive y-values exceeds some limit:
filter(lim) = 'awk ''{if(NR > 1 && sqrt((y-$2)**2) > '.lim.') print ""; print; y=$2}'' test.dat'
plot '< '.filter(3) using 1:2 with lines
Note, that I used the sqrt((..)**2) only to simulate an abs function, which awk doesn't have.