Python 从基因组中创建一个Dendogram
我想利用基因组数据:Python 从基因组中创建一个Dendogram,python,bioinformatics,hierarchical-clustering,dendrogram,genome,Python,Bioinformatics,Hierarchical Clustering,Dendrogram,Genome,我想利用基因组数据: Species_A = ctnngtggaccgacaagaacagtttcgaatcggaagcttgcttaacgtag Species_B = ctaagtggactgacaggaactgtttcgaatcggaagcttgcttaacgtag Species_C = ctacgtggaccgacaagaacagtttcgactcggaagcttgcttaacgtag Species_D = ctacgtggaccgacaagaacagtttcgactcggaagct
Species_A = ctnngtggaccgacaagaacagtttcgaatcggaagcttgcttaacgtag
Species_B = ctaagtggactgacaggaactgtttcgaatcggaagcttgcttaacgtag
Species_C = ctacgtggaccgacaagaacagtttcgactcggaagcttgcttaacgtag
Species_D = ctacgtggaccgacaagaacagtttcgactcggaagcttgcttaacgccg
Species_E = ctgtgtggancgacaaggacagttccaaatcggaagcttgcttaacacag
我想创建一个树状图,根据上面的基因组序列,这些生物彼此之间的关系有多密切。我首先计算每个物种的a、c、t和g的数量,然后创建一个数组,然后绘制一个树状图:
gen_size1 = len(Species_A)
a1 = float(Species_A.count('a'))/float(gen_size1)
c1 = float(Species_A.count('c'))/float(gen_size1)
g1 = float(Species_A.count('g'))/float(gen_size1)
t1 = float(Species_A.count('t'))/float(gen_size1)
.
.
.
gen_size5 = len(Species_E)
a5 = float(Species_E.count('a'))/float(gen_size5)
c5 = float(Species_E.count('c'))/float(gen_size5)
g5 = float(Species_E.count('g'))/float(gen_size5)
t5 = float(Species_E.count('t'))/float(gen_size5)
my_genes = np.array([[a1,c1,g1,t1],[a2,c2,g2,t2],[a3,c3,g3,t3],[a4,c4,g4,t4],[a5,c5,g5,t5]])
plt.subplot(1,2,1)
plt.title("Mononucleotide")
linkage_matrix = linkage(my_genes, "single")
print linkage_matrix
dendrogram(linkage_matrix,truncate_mode='lastp', color_threshold=1, labels=[Species_A, Species_B, Species_C, Species_D, Species_E], show_leaf_counts=True)
plt.show()
物种A和B是同一种生物的变种,我认为它们都应该从根的一个共同分支中分离出来,物种C和D也是如此,它们应该从根的另一个普通分支分化,然后物种E从主根分化,因为它与物种A到D无关。不幸的是,树状图结果与从普通分支分化的物种A和E混淆,然后是另一个分支中的物种C、D和B(相当混乱)
我读过关于基因组序列的层次聚类,但我观察到它只适用于二维系统,不幸的是,我有4个维度,即a、c、t和g。还有其他的策略吗?谢谢你的帮助 好吧,使用你可以使用自定义的距离(我的赌注是Needleman Wunsch或Smith Waterman作为起点)。是如何处理输入数据的示例。你也应该检查一下。设置好后,可以使用更高级的对齐方法,如。您可以提取基因组之间的关系,并在创建树状图时使用它们 这是生物信息学中一个相当常见的问题,因此您应该使用内置了此功能的生物信息学库 首先,使用序列创建一个multi-FASTA文件:
import os
from Bio import SeqIO
from Bio.Seq import Seq
from Bio.SeqRecord import SeqRecord
from Bio.Alphabet import generic_dna
sequences = ['ctnngtggaccgacaagaacagtttcgaatcggaagcttgcttaacgtag',
'ctaagtggactgacaggaactgtttcgaatcggaagcttgcttaacgtag',
'ctacgtggaccgacaagaacagtttcgactcggaagcttgcttaacgtag',
'ctacgtggaccgacaagaacagtttcgactcggaagcttgcttaacgccg',
'ctgtgtggancgacaaggacagttccaaatcggaagcttgcttaacacag']
my_records = [SeqRecord(Seq(sequence, generic_dna),
id='Species_{}'.format(letter), description='Species_{}'.format(letter))
for sequence, letter in zip(sequences, 'ABCDE')]
root_dir = r"C:\Users\BioGeek\Documents\temp"
filename = 'my_sequences'
fasta_path = os.path.join(root_dir, '{}.fasta'.format(filename))
SeqIO.write(my_records, fasta_path, "fasta")
这将创建文件C:\Users\BioGeek\Documents\temp\my\u sequences.fasta
,如下所示:
>Species_A
ctnngtggaccgacaagaacagtttcgaatcggaagcttgcttaacgtag
>Species_B
ctaagtggactgacaggaactgtttcgaatcggaagcttgcttaacgtag
>Species_C
ctacgtggaccgacaagaacagtttcgactcggaagcttgcttaacgtag
>Species_D
ctacgtggaccgacaagaacagtttcgactcggaagcttgcttaacgccg
>Species_E
ctgtgtggancgacaaggacagttccaaatcggaagcttgcttaacacag
接下来,使用命令行工具ClustalW
执行多序列对齐:
from Bio.Align.Applications import ClustalwCommandline
clustalw_exe = r"C:\path\to\clustalw-2.1\clustalw2.exe"
assert os.path.isfile(clustalw_exe), "Clustal W executable missing"
clustalw_cline = ClustalwCommandline(clustalw_exe, infile=fasta_path)
stdout, stderr = clustalw_cline()
print stdout
这张照片是:
CLUSTAL 2.1 Multiple Sequence Alignments
Sequence format is Pearson
Sequence 1: Species_A 50 bp
Sequence 2: Species_B 50 bp
Sequence 3: Species_C 50 bp
Sequence 4: Species_D 50 bp
Sequence 5: Species_E 50 bp
Start of Pairwise alignments
Aligning...
Sequences (1:2) Aligned. Score: 90
Sequences (1:3) Aligned. Score: 94
Sequences (1:4) Aligned. Score: 88
Sequences (1:5) Aligned. Score: 84
Sequences (2:3) Aligned. Score: 90
Sequences (2:4) Aligned. Score: 84
Sequences (2:5) Aligned. Score: 78
Sequences (3:4) Aligned. Score: 94
Sequences (3:5) Aligned. Score: 82
Sequences (4:5) Aligned. Score: 82
Guide tree file created: [C:\Users\BioGeek\Documents\temp\my_sequences.dnd]
There are 4 groups
Start of Multiple Alignment
Aligning...
Group 1: Sequences: 2 Score:912
Group 2: Sequences: 2 Score:921
Group 3: Sequences: 4 Score:865
Group 4: Sequences: 5 Score:855
Alignment Score 2975
CLUSTAL-Alignment file created [C:\Users\BioGeek\Documents\temp\my_sequences.aln]
创建的my_sequences.dnd
文件ClustalW
是一个标准文件,Bio.Phylo
可以解析以下内容:
from Bio import Phylo
newick_path = os.path.join(root_dir, '{}.dnd'.format(filename))
tree = Phylo.read(newick_path, "newick")
Phylo.draw_ascii(tree)
其中打印:
____________ Species_A
____|
| |_____________________________________ Species_B
|
_| ____ Species_C
|_________|
| |_________________________ Species_D
|
|__________________________________________________________________ Species_E
或者,如果安装了matplotlib
或pylab
,则可以使用draw
功能创建图形:
tree.rooted = True
Phylo.draw(tree, branch_labels=lambda c: c.branch_length)
产生:
这张树状图清楚地说明了你所观察到的:物种A和B是同一生物体的变种,它们都从根的一个共同分支中分化出来。物种C和D也是如此,它们都从根的另一个共同分支中分化出来。最后,物种E与主根不同,因为它与物种A到D无关。这太神奇了!非常感谢!我想问一下,我们是否可以显示聚类系数?@TouyaD.Serdan答案过于详细,无法作为评论。你能提出一个新问题吗?