Python: how to slice a csv file with respect to a column other than the first? -


i have csv file displays number of columns , 500000 rows. need slice file respect second column, displays year, maintaining other columns:

col1   col2   col3   col4   col5   col6   col7 xxx    1986   xxx    xxx    xxx    xxx    xxx xxx    1992   xxx    xxx    xxx    xxx    xxx xxx    1998   xxx    xxx    xxx    xxx    xxx ...    ...    ...    ...    ...    ...    ... xxx    2015   xxx    xxx    xxx    xxx    xxx xxx    1984   xxx    xxx    xxx    xxx    xxx

my question: how can produce csv file out of this, values in second column >=1992?

desired output:

col1   col2   col3   col4   col5   col6   col7 xxx    1992   xxx    xxx    xxx    xxx    xxx xxx    1998   xxx    xxx    xxx    xxx    xxx xxx    2015   xxx    xxx    xxx    xxx    xxx

my attempt this, got stuck @ point should insert if linked second column, don't know how that:

from __future__ import division import numpy numpy import * import csv collections import * import os import glob  directorypath=raw_input('working directory: ') #indicates csv file located i,file in enumerate(os.listdir(directorypath)): #loops on folder csv files     if file.endswith(".csv"): #checks if csv files         filename=os.path.basename(file) #takes complete path file         filelabel=file #takes filename         strpath = os.path.join(directorypath, file) #retrieves complete path find csv file         x=numpy.genfromtxt(strpath, delimiter=',')[:,7] #i got stuck here

you can iterate on rows of csv see if value in col2 >= year interested in. if is, add row new list. pass in new list csv writer. can call function in loop create new csvs files ending csv extension.

you have pass in working_directory , year. folder of csvs want process.

import csv import os def make_csv(in_file, out_file, year):     open(in_file, 'rb') csv_in_file:         csv_row_list = []         first_row = true         csv_reader = csv.reader(csv_in_file)         row in csv_reader:             if first_row:                 csv_row_list.append(row)                 first_row = false             else:                 if int(row[1]) >= year:                     csv_row_list.append(row)      open(out_file, 'wb') csv_out_file:         csv_writer = csv.writer(csv_out_file)         csv_writer.writerows(csv_row_list)  root, directories, files in os.walk(working_directory):     f in files:         if f.endswith('.csv'):             in_file = os.path.join(root, f)             out_file = os.path.join(root, os.path.splitext(f)[0] + '_new' + os.path.splitext(f)[1])             make_csv(in_file, out_file, year)

Comments

Post a Comment

Popular posts from this blog

java - pagination of xlsx file to XSSFworkbook using apache POI -

right in code, reading xlsx file, xssfworkbook, , writing database. but, when size of xlsx file increases, causes outofmemory error. can not increase server size, or divide xlsx file pieces. tried loading workbook using file (instead of inputstream), didn't either. i looking way read 10k rows @ time (instead of entire file @ once) , iteratively write workbook , database. is there way apache poi? poi contains called "eventmodel" designed purpose. it's mentioned in faq : the ss eventmodel package api reading excel files without loading whole spreadsheet memory. require more knowledge on part of user, reduces memory consumption more tenfold. based on awt event model in combination sax. if need read-only access, best way it. however, may want double check first if issue somewhere else. check out this item : i think poi using memory! can do? 1 comes quite lot, reason isn't might think. so, first thing check - what's source of prob...
Read more

Unlimited choices in BASH case statement -

consider simple bash snippet: case $option in 1) image=${options[0]%.tar} ;; 2) image=${options[1]%.tar} ;; 3) image=${options[2]%.tar} ;; 4) image=${options[3]%.tar} ;; *) echo "invalid option" exit 1 esac in real script numbers goes 30. makes pretty long. can somehow specify cases variable? something this: case $option in $i) image=${options[$(($i-1))]%.tar} any pointer appreciated. you can match against multiple patterns in single clause: case $option in 1|2|3: echo "$option one, 2 or three" ;; esac if still typing you, can use simple pattern matching: case $option in # following matches # - single-digit numbers 0-9 # - two-digit numbers starting either 1 or 2 # - number 30 [0-9]|[12][0-9]|30) image=${options[$(($option-1))]%.tar} ;; *) echo "invalid option" 1>&2 exit 1 esac
Read more

apache - How do I stop my index.php being run twice for every user -

we've got webapp initial html served using apache , php. i noticed index.php being run twice every request. seems caused / effected rewrite rules in our .htaccess - rewritecond %{http_host} ^(www\.|hotels\.)ourdomain\.com$ [nc,or] rewritecond %{server_name} ^(www\.|hotels\.)ourdomain\.com$ [nc] rewriterule (.*) http://ourdomain.com/$1 [r=301] rewriterule ^hotels/([^/]+)/?\??(.*)$ ?d=$1&$2 [qsa] the final rule moving parameter url path query string. i.e. http://ourdomain.com/hotels/vegas?someparam=1 becomes http://ourdomain.com?d=vegas&someparam=1 if go directly query string version index.php run once. if use url redirected, index.php run twice (i'm checking adding error_log('end of index.php') file). so example going http://ourdomain.com/hotels/paris hits file twice http://ourdomain.com?d=paris hits once. i've seen this question , had @ blog mentioned , , can't find empty string url's (i've tried using yslow process). ...
Read more