seqio

A c library for reading and writing sequences in fasta and fastq format.

Inspired by kseq.h, another library for reading fasta and fastq files.

features

• Read and write fasta and fastq files
• Support for gzipped files
• Intuitive API

Quick start

Python

WIP: I'm working on a python wrapper for this library.

os	reading	writing
Linux	✅	🚧
MacOS	🚧	🚧
Windows	🚧	🚧

Install

pip install fastseqio

from seqio import seqioFile

# default open mode is Read
# auto detect gzip
file = seqioFile("test-data/test2.fa")

for record in file:
  print(record.name)
  print(record.sequence)
  print(len(record))

# read from stdin
from seqio import seqioStdinFile

file = seqioStdinFile()

for record in file:
  print(record.name)
  print(record.sequence)
  print(len(record))

C

// main.c
#include "seqio.h"
#include <stdio.h>

int
main(int argc, char* argv[])
{
  if (argc == 1) {
    fprintf(stderr, "Usage: %s <in.fasta>\n", argv[0]);
    return 1;
  }
  // Step1: set open options
  seqioOpenOptions openOptions = {
    .filename = argv[1],
    .mode = seqOpenModeRead,
  };
  // Step2: open file
  seqioFile* sf = seqioOpen(&openOptions);
  // step3: read records
  seqioRecord* record = NULL;
  // step4: read records one by one
  while ((record = seqioRead(sf, record)) != NULL) {
    // setp5: do something with the record
    printf("name: %s: %lu\n", record->name->data, record->sequence->length);
    // !!! Do not free record, 
    // !!! beacuse it will be freed by seqioRead automatically.
  }
  // step6: close file
  seqioClose(sf);
}

gcc -o main main.c seqio.c -lz
./main test.fasta

API & Structure

seqioOpenOptions

typedef enum {
  seqOpenModeRead,
  seqOpenModeWrite,
} seqOpenMode;

typedef struct {
  char* filename;   // filename
  bool isGzipped;   // it will be detected automatically if mode is seqOpenModeRead
  seqOpenMode mode; // default is seqOpenModeRead
} seqioOpenOptions;

open File

/**
  * @brief open a file
  * @param options open options
  * @return seqioFile* file
 */
seqioFile* seqioOpen(seqioOpenOptions* options);

/**
  * @brief open a file from stdin
  * @return seqioFile* file
 */
seqioFile* seqioStdinOpen();

/**
  * @brief write to stdout
  * @return seqioFile* file
 */
seqioFile* seqioStdoutOpen();

/**
  * @brief close a file
  * @param file
 */
void seqioClose(seqioFile* file);

record

typedef enum {
  seqioRecordTypeFasta,
  seqioRecordTypeFastq,
  seqioRecordTypeUnknown
} seqioRecordType;

typedef struct {
  size_t length;
  size_t capacity;
  char* data;
} seqioString;

typedef struct {
  seqioRecordType type;
  seqioString* name;
  seqioString* comment;
  seqioString* sequence;
  seqioString* quality;
} seqioRecord;

while reading a record, the memory of the record will be allocated automatically, and it will be used repeatedly. So you don't need to free the memory of the record. At the end of the file, the memory of the record will be freed automatically.

A record will be freed when the following conditions are met:

• All records are read by seqioRead or seqioReadFasta or seqioReadFastq
• The file is closed by seqioClose

read record

/**
  * @brief read a record
  * @param file
  * @param record
  * @return seqioRecord* record or NULL if the file is end
 */
seqioRecord* seqioRead(seqioFile* file, seqioRecord* record);

/**
  * @brief read a record in fasta format
  * @param file
  * @param record
  * @return seqioRecord* record or NULL if the file is end
 */
seqioRecord* seqioReadFastq(seqioFile* file, seqioRecord* record);

/**
  * @brief read a record in fastq format
  * @param file
  * @param record
  * @return seqioRecord* record or NULL if the file is end
 */
seqioRecord* seqioReadFasta(seqioFile* file, seqioRecord* record);

write record

typedef struct {
  size_t lineWidth;      // fasta file line width (default: 0, no wrap)
  bool includeComment;   // include comment in fasta record (default: true)
  baseCase baseCase;     // base case (default: original)
} seqioWriteOptions;

/**
  * @brief write a fasta record
  * @param file
  * @param record
  * @param options
 */
void seqioWriteFasta(seqioFile* sf, seqioRecord* record, seqioWriteOptions* options);

/**
  * @brief write a fastq record
  * @param file
  * @param record
  * @param options
 */
void seqioWriteFastq(seqioFile* file, seqioRecord* record, seqioWriteOptions* options);

example

more examples can be found in the test/benchmark folder.

memory check

valgrind --leak-check=full --leak-check=full --show-leak-kinds=all --log-file=./1.log --track-origins=yes ./main

==1139682== Memcheck, a memory error detector
==1139682== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==1139682== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info
==1139682== Command: ./main
==1139682== Parent PID: 1107213
==1139682== 
==1139682== 
==1139682== HEAP SUMMARY:
==1139682==     in use at exit: 0 bytes in 0 blocks
==1139682==   total heap usage: 45 allocs, 45 frees, 151,872 bytes allocated
==1139682== 
==1139682== All heap blocks were freed -- no leaks are possible
==1139682== 
==1139682== For lists of detected and suppressed errors, rerun with: -s
==1139682== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

benchmark

For this benchmark, I re-used sequence files from SeqKit benchmark: seqkit-benchmark-data.tar.gz

file	format	type	num_seqs	sum_len	min_len	avg_len	max_len
dataset_A.fa	FASTA	DNA	67,748	2,807,643,808	56	41,442.5	5,976,145
dataset_B.fa	FASTA	DNA	194	3,099,750,718	970	15,978,096.5	248,956,422
dataset_C.fq	FASTQ	DNA	9,186,045	918,604,500	100	100	100

python benchmark.py

Machine info

GCC: gcc version 12.2.0 (Debian 12.2.0-14)
OS: Linux 5.15.133.1-microsoft-standard-WSL2 #1 SMP Thu Oct 5 21:02:42 UTC 2023 x86_64 GNU/Linux
CPU: 11th Gen Intel(R) Core(TM) i5-11500 @ 2.70GHz
RAM: 16G

Result

Read fasta and fastq files with 1 thread.

file	seqio	kseq
dataset_A.fa	0.791 s	1.052 s
dataset_B.fa	1.467 s	1.925 s
dataset_C.fq	1.404 s	1.162 s