How to make continuous line with missing data in gnuplot

Question

I have some data with missing entries, which are substituted with ?'s, here's a snippet:

20  0.8793  2.14765 1.57448 0.808   1.08829 0.86717
21  0.88832 2.23218 1.57538 0.92825 1.20609 ?
22  1.83701 2.9006  2.29899 1.83901 2.11604 ?
23  ?       4.11525 3.6469  2.95346 ?       ?
24  ?       4.62305 4.76381 ?       ?       4.06512
25  6.12763 5.41329 6.35681 6.15967 6.4376  6.13264
26  4.5513  5.80511 4.97664 4.59429 4.88697 4.5918
27  ?       3.34182 ?       ?       ?       ?

When I try to plot this using the command

plot "datafile.txt" u 1:2 w lp

the graph is not continuous, as shown in this example .

I want the graph to display with linespoints and to be continuous only in this example. I use this data for other graphs where I need them to be discontinuous.

Is there something I can do? Thanks.

Answer 1

With the data you are providing, I cannot reproduce your issue. I will get a continuous line. Your actual data or settings seem to be different.

Code:

### missing data
reset session

$Data <<EOD
20  0.8793  2.14765 1.57448 0.808   1.08829 0.86717
21  0.88832 2.23218 1.57538 0.92825 1.20609 ?
22  1.83701 2.9006  2.29899 1.83901 2.11604 ?
23  ?       4.11525 3.6469  2.95346 ?       ?
24  ?       4.62305 4.76381 ?       ?       4.06512
25  6.12763 5.41329 6.35681 6.15967 6.4376  6.13264
26  4.5513  5.80511 4.97664 4.59429 4.88697 4.5918
27  ?       3.34182 ?       ?       ?       ?
EOD

plot $Data u 1:2 w lp pt 7
### end of code

Result: