file io - Python glob gives no result -


i have directory contains lot of .csv files, , trying write script runs on files in directory while doing following operation:

remove first , last lines csv files

i running following code:

import glob  list_of_files = glob.glob('path/to/directory/*.csv') file_name in list_of_files:     fi = open(file_name, 'r')     fo = open(file_name.replace('csv', 'out'), 'w')  #make new output file each file     num_of_lines = file_name.read().count('\n')     file_name.seek(0)     = 0     line in fi:         if != 1 , != num_of_lines-1:             fo.write(line)      fi.close()     fo.close()

and run script using python3 script.py. though don't error, don't output file either.

there multiple issues in code. first of count number of lines on filename instead of file-object. second problem initialize i=0 , compare against never changes.

personally convert file list of "lines", cut off first , last , write of them new file:

import glob  list_of_files = glob.glob('path/to/directory/*.csv') file_name in list_of_files:     open(file_name, 'r') fi:         open(file_name.replace('csv', 'out'), 'w') fo:             line in list(fi)[1:-1]:  # lines except first , last                 fo.write(line)

using with open allows omit close calls (because done implicitly) if exception occurs.

in case still gives no output print statement shows file being processed:

print(file_name)  # inside for-loop before `open` calls.

since you're using python-3.5 use pathlib:

import pathlib  path = pathlib.path('path/to/directory/')  # make sure it's valid directory assert path.is_dir(), "{} not valid directory".format(p.absolute())  file_name in path.glob('*.csv'):     file_name.open('r') fi:         pathlib.path(str(file_name).replace('.csv', '.out')).open('w') fo:             line in list(fi)[1:-1]:  # lines except first , last                 fo.write(line)

as jon clements pointed out there better way [1:-1] exclude first , last line using generator function. way reduce amount of memory used , might improve overall performance. example use:

import pathlib  def ignore_first_and_last(it):     = iter(it)     firstline = next(it)     lastline = next(it)     nxtline in it:         yield lastline         lastline = nxtline  path = pathlib.path('path/to/directory/')  # make sure it's valid directory assert path.is_dir(), "{} not valid directory".format(p.absolute())  file_name in path.glob('*.csv'):     file_name.open('r') fi:         pathlib.path(str(file_name).replace('.csv', '.out')).open('w') fo:             line in ignore_first_and_last(fi):  # lines except first , last                 fo.write(line)

Comments

Post a Comment

Popular posts from this blog

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

python Tkinter Capturing keyboard events save as one single string -

is possible store keyboard events 1 string? code below stores 1 char , prints it. card reader or bar code reader, contains collection of character/ string not 1 character @ time. goal save char pressed text variable. from tkinter import * root = tk() def key(event): text= event.char text+= event.char print ("pressed", text) def callback(event): frame.focus_set() print ("clicked at", event.x, event.y) frame = frame(root, width=100, height=100) frame.bind("<key>", key) frame.bind("<button-1>", callback) frame.pack() root.mainloop() currently, creating text variable , everytime key() function gets called, , text stores last character typed. you can define text module level variable , , use module level text inside key function - text = '' def key(event): global text text+= event.char print("pressed", text)
Read more

sql server - Why does Linq-to-SQL add unnecessary COUNT()? -

here tables: create table customer ( cid int primary key, name varchar(32) ) create table ord ( oid int primary key, cid int foreign key references customer, address varchar(20) ) here's linq-to-sql statement: var aaa = c in db.customer select new { c, o = c.ord.tolist() }; and here's inexplicable query generated linq-to-sql: select [t0].[cid] [cid], [t0].[name] [name], [t1].[oid] [oid], [t1].[cid] [cid2], [t1].[address] [address], (select count(*) [dbo].[ord] [t2] [t2].[cid] = [t0].[cid]) [value] [dbo].[customer] [t0] left outer join [dbo].[ord] [t1] on [t1].[cid] = [t0].[cid] order [t0].[cid], [t1].[oid] i want understand how rid of count(*) part. it's entirely uncalled for! linq needs count(*) in order determine number of entries returned o = c.ord.tolist() .
Read more