Error: must be str, not generator in Python
python
Solution
`bc[base.upper()] for base in chr_string[newstart:newend]` is a generator expression. You need to make a string from that via e.g. `join` method: `''.join(c[base.upper()] for base in chr_string[newstart:newend])`
Problem
I am using python and here is a piece of my code: ``` wp = open(outfile, 'w') fields = line.split('\t') gene_ID = fields[0] chr = fields[1] strand = fields[2] start = int(fields[3]) end = int(fields[4]) bc = {'A': 'T', 'C': 'G', 'G': 'C', 'T': 'A', 'N':'N'} if strand == '+': wp.write(chr_string[start:end]) if strand == '-': newstart, newend = -(start + 1), -(end + 1) wp.write(bc[base.upper()] for base in chr_string[newstart:newend]) <--error pointed at this line ``` When I try to run my whole code, I get the following message: ``` TypeError: must be str, not generator ``` Does anyone know what is wrong with my code that is prompting this?