In many cases tables are stored in some sort of unstructured plain text format, with cells separated by spaces or some other delimiters. There is a wide variety of such formats depending on what delimiters are used, how columns are identified, whether blank values are permitted and so on. It is impossible to cope with them all, but TOPCAT attempts to make a good guess about how to interpret a given ASCII file as a table, which in many cases is successful. In particular, if you just have columns of numbers separated by something that looks like spaces, you should be just fine.
Here are the detailed rules for how the ASCII-format tables are interpreted:
null
" (unquoted) represents
the null valueBoolean
,
Short
Integer
,
Long
,
Float
,
Double
,
String
NaN
for not-a-number, which is treated the same as a
null value for most purposes, and Infinity
or inf
for infinity (with or without a preceding +/- sign).
These values are matched case-insensitively.If the list of rules above looks frightening, don't worry, in many cases it ought to make sense of a table without you having to read the small print. Here is an example of a suitable ASCII-format table:
# # Here is a list of some animals. # # RECNO SPECIES NAME LEGS HEIGHT/m 1 pig "Pigling Bland" 4 0.8 2 cow Daisy 4 2 3 goldfish Dobbin "" 0.05 4 ant "" 6 0.001 5 ant "" 6 0.001 6 ant '' 6 0.001 7 "queen ant" 'Ma\'am' 6 2e-3 8 human "Mark" 2 1.8In this case it will identify the following columns:
Name Type ---- ---- RECNO Short SPECIES String NAME String LEGS Short HEIGHT/m FloatIt will also use the text "
Here is a list of some animals
"
as the Description parameter of the table.
Without any of the comment lines, it would still interpret the table,
but the columns would be given the names col1
..col5
.
If you understand the format of your files but they don't exactly match the criteria above, the best thing is probably to write a simple free-standing program or script which will convert them into the format described here. You may find Perl or awk suitable languages for this sort of thing.
This format is not detected automatically - you must specify that
you wish to load a table in ascii
format.