Python open Function
Python file object can open, read and write files.
Suppose a text file "tp.txt" with following content:
TTN 27 33 60 54 GATA3 38 20 17 35 HLA-DRB6 18 15 24 27 MUC16 13 15 28 26
The Python script file "test.py" is as follows:
with open("tp.txt") as rad:#rad is a file object for read for linein rad: print("line: " + line.rstrip('\n'))
C:\> test.py
line: TTN 27 33 60 54 line: GATA3 38 20 17 35 line: HLA-DRB6 18 15 24 27 line: MUC16 13 15 28 26
Following Python code can do the same thing (traditional method).
rad = open("tp.txt")
for line in rad:
print("line: " + line.rstrip('\n'))
rad.close()
open a file to write:
writ = open("tp.txt","w+") #writ is a file object for write
writ.write("line 1 content\n")
writ.writelines("line 2 by writeline\n")
writ.writelines("line 3 by writeline\n")
writ.close()
C:\> test.py
line 1 content line 2 by writeline line 3 by writeline
open function syntax:
open(file[, mode][, buffer_size])
If no buffer size is specified, no buffering while reading. If buffer_size = 1, line buffering will be performed. If buffer_size > 1, the specified value will be used for buffer size. If buffer_size < 0, the system default will be used as buffer size.
open mode list:| mode | description |
| r | read in text mode |
| w | write in text mode, overwrite old file if exists |
| a | append in text mode |
| r+ | read and write |
| w+ | read and write, overwrite old file if exists |
| a+ | read and append |
| rb | read in binary mode |
| wb | write in binary mode, overwrite old file if exists |
| ab | append in binary mode |
| rb+ | read and write in binary mode |
| wb+ | write and read in binary mode, overwrite old file if exists |
| ab+ | append and read in binary mode |
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