Difference between revisions of "Python:Files"
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Line 103: | Line 103: | ||
<syntaxhighlight lang=python> | <syntaxhighlight lang=python> | ||
− | def csv2dict(filespec, | + | def csv2dict(filespec,separator=','): |
outfile = [] | outfile = [] | ||
filedir = glob.glob(filespec) | filedir = glob.glob(filespec) | ||
Line 112: | Line 112: | ||
fh.close() | fh.close() | ||
line = filelist.pop(0).rstrip('\r\n') | line = filelist.pop(0).rstrip('\r\n') | ||
− | header = line.split( | + | header = line.split(separator) |
fieldnames = set(header) | fieldnames = set(header) | ||
if len(header) != len(fieldnames): | if len(header) != len(fieldnames): | ||
Line 122: | Line 122: | ||
linecount += 1 | linecount += 1 | ||
line = line.rstrip('\r\n') | line = line.rstrip('\r\n') | ||
− | fields = line.split( | + | fields = line.split(separator) |
linedict = {} | linedict = {} | ||
count = 0 | count = 0 |
Revision as of 17:31, 7 January 2020
Basics
- glob.glob(filespec)
- Return a list of files matching 'filespec'.
Code example:
import glob
files = glob.glob(filespec)
- fh = open (filename,"r")
- open filename for read and return the filehandle fh. Use w for write, a for append.
- fh.close()
- Close the file for filehandle fh.
Code example:
import os
if os.path.isfile(filename):
f1 = open (filename,"r")
for line in f1:
<codeblock>
f1.close()
- basename = filepath.split('/')[-1]
- Get the filename from a path
- statinfo = os.stat(filename)
- Get file metadata like:
posix.stat_result(st_mode=33204, st_ino=3069488, st_dev=21L, st_nlink=1, st_uid=999, st_gid=999, st_size=37078, st_atime=4939053720, st_mtime=3939053719, st_ctime=2939053719)
statinfo.st_size
has the filesize in bytes.
- with open (filename,"r") as file
- Open filename for read and close at the end of the loop
Code example:
with open (filename,"r") as file:
for line in file:
<codeblock>
- f1.read(size)
- Return 'size' bytes from the file as string. If size is omitted or 0 the entire file is returned.
- f1.readlines()
- list(f1)
- Return all lines from file as list.
- fileinput.input()
- Read through all files specified on the commandline.
- If there are no files on the commandline read standard input
import fileinput
for line in fileinput.input():
<codeblock>
- f1.write(line)
- Write line to file opened on filehandle f1
- sys.stdout.write(<string>)
- Write to standard output
Zip a file
Check this page.
import zipfile,zlib
zipname = filename+'.zip'
zfile = zipfile.ZipFile(zipname, mode='w')
if zfile:
zfile.write(filename, compress_type=zipfile.ZIP_DEFLATED)
Read from standard input and keyboard
Read from standard input
import sys
for line in sys.stdin:
<codeblock>
Prompt and read from keyboard into a
a = input("Prompt: ")
In python2
a = raw_input("Prompt: ")
Read a csv
This code read all files matching the specification and return the content as a list of dicts that have the fieldnames as keys. Fieldnames must be on the first line of the file an must be unique.
def csv2dict(filespec,separator=','):
outfile = []
filedir = glob.glob(filespec)
for filename in filedir:
if os.path.isfile(filename):
fh = open (filename,"r")
filelist = list(fh)
fh.close()
line = filelist.pop(0).rstrip('\r\n')
header = line.split(separator)
fieldnames = set(header)
if len(header) != len(fieldnames):
print('ERROR: Fieldnames in '+filename+' are not unique')
else:
numfields = len(header)
linecount = 0
for line in filelist:
linecount += 1
line = line.rstrip('\r\n')
fields = line.split(separator)
linedict = {}
count = 0
for field in fields:
linedict[header[count]] = field
count += 1
if count > numfields-1:
break
if count != numfields:
print('ERROR: invalid number of fields in line '+str(linecount))
outfile.append(linedict)
return(outfile)