Nucleic Acid Sequences and Structures

Defines

VRNA_OPTION_MULTILINE

#include <ViennaRNA/io/file_formats.h>

Tell a function that an input is assumed to span several lines.

If used as input-option a function might also be returning this state telling that it has read data from multiple lines.

VRNA_CONSTRAINT_MULTILINE

#include <ViennaRNA/io/file_formats.h>

parse multiline constraint

Deprecated:: see vrna_extract_record_rest_structure()

VRNA_INPUT_VERBOSE: #include <ViennaRNA/io/file_formats.h>

Functions

void vrna_file_helixlist(const char *seq, const char *db, float energy, FILE *file)

#include <ViennaRNA/io/file_formats.h>

Print a secondary structure as helix list.

Parameters:

seq – The RNA sequence
db – The structure in dot-bracket format
energy – Free energy of the structure in kcal/mol
file – The file handle used to print to (print defaults to ‘stdout’ if(file == NULL) )

void vrna_file_connect(const char *seq, const char *db, float energy, const char *identifier, FILE *file)

#include <ViennaRNA/io/file_formats.h>

Print a secondary structure as connect table.

Connect table file format looks like this:

* 300  ENERGY = 7.0  example
* 1 G       0    2   22    1
* 2 G       1    3   21    2
*

where the headerline is followed by 6 columns with:

Base number: index n
Base (A, C, G, T, U, X)
Index n-1 (0 if first nucleotide)
Index n+1 (0 if last nucleotide)
Number of the base to which n is paired. No pairing is indicated by 0 (zero).
Natural numbering.

Parameters:

seq – The RNA sequence
db – The structure in dot-bracket format
energy – The free energy of the structure
identifier – An optional identifier for the sequence
file – The file handle used to print to (print defaults to ‘stdout’ if(file == NULL) )

void vrna_file_bpseq(const char *seq, const char *db, FILE *file)

#include <ViennaRNA/io/file_formats.h>

Print a secondary structure in bpseq format.

Parameters:

seq – The RNA sequence
db – The structure in dot-bracket format
file – The file handle used to print to (print defaults to ‘stdout’ if(file == NULL) )

void vrna_file_json(const char *seq, const char *db, double energy, const char *identifier, FILE *file)

#include <ViennaRNA/io/file_formats.h>

Print a secondary structure in jsonformat.

Parameters:

seq – The RNA sequence
db – The structure in dot-bracket format
energy – The free energy
identifier – An identifier for the sequence
file – The file handle used to print to (print defaults to ‘stdout’ if(file == NULL) )

unsigned int vrna_file_fasta_read_record(char **header, char **sequence, char ***rest, FILE *file, unsigned int options)

#include <ViennaRNA/io/file_formats.h>

Get a (fasta) data set from a file or stdin.

This function may be used to obtain complete datasets from a filehandle or stdin. A dataset is always defined to contain at least a sequence. If data starts with a fasta header, i.e. a line like

>some header info

then vrna_file_fasta_read_record() will assume that the sequence that follows the header may span over several lines. To disable this behavior and to assign a single line to the argument ‘sequence’ one can pass VRNA_INPUT_NO_SPAN in the ‘options’ argument. If no fasta header is read in the beginning of a data block, a sequence must not span over multiple lines!

Unless the options VRNA_INPUT_NOSKIP_COMMENTS or VRNA_INPUT_NOSKIP_BLANK_LINES

are passed, a sequence may be interrupted by lines starting with a comment character or empty lines.

A sequence is regarded as completely read if it was either assumed to not span over multiple lines, a secondary structure or structure constraint follows the sequence on the next line, or a new header marks the beginning of a new sequence…

All lines following the sequence (this includes comments) that do not initiate a new dataset according to the above definition are available through the line-array ‘rest’. Here one can usually find the structure constraint or other information belonging to the current dataset. Filling of ‘rest’ may be prevented by passing VRNA_INPUT_NO_REST to the options argument.

The main purpose of this function is to be able to easily parse blocks of data in the header of a loop where all calculations for the appropriate data is done inside the loop. The loop may be then left on certain return values, e.g.:

char *id, *seq, **rest;
int  i;
id = seq = NULL;
rest = NULL;
while(!(vrna_file_fasta_read_record(&id, &seq, &rest, NULL, 0) & (VRNA_INPUT_ERROR | VRNA_INPUT_QUIT))){
  if(id)
    printf("%s\n", id);
  printf("%s\n", seq);
  if(rest)
    for(i=0;rest[i];i++){
      printf("%s\n", rest[i]);
      free(rest[i]);
    }
  free(rest);
  free(seq);
  free(id);
}

In the example above, the while loop will be terminated when vrna_file_fasta_read_record() returns either an error, EOF, or a user initiated quit request.

As long as data is read from stdin (we are passing NULL as the file pointer), the id is printed if it is available for the current block of data. The sequence will be printed in any case and if some more lines belong to the current block of data each line will be printed as well.

Note

This function will exit any program with an error message if no sequence could be read!

This function is NOT threadsafe! It uses a global variable to store information about the next data block. Do not forget to free the memory occupied by header, sequence and rest!

Parameters:

header – A pointer which will be set such that it points to the header of the record
sequence – A pointer which will be set such that it points to the sequence of the record
rest – A pointer which will be set such that it points to an array of lines which also belong to the record
file – A file handle to read from (if NULL, this function reads from stdin)
options – Some options which may be passed to alter the behavior of the function, use 0 for no options

Returns:

A flag with information about what the function actually did read

char *vrna_extract_record_rest_structure(const char **lines, unsigned int length, unsigned int option)

#include <ViennaRNA/io/file_formats.h>

Extract a dot-bracket structure string from (multiline)character array.

This function extracts a dot-bracket structure string from the ‘rest’ array as returned by vrna_file_fasta_read_record() and returns it. All occurences of comments within the ‘lines’ array will be skipped as long as they do not break the structure string. If no structure could be read, this function returns NULL.