Writing lines to a csv file in a for loop in python -

i have large csv file 5000 rows in it. first column contains identifying names each row i.e. lhgzz01 first 9 rows have lhgzz01 name next 10 have else , on. there no pattern such used np.unique find index name changes.

i want write loop write each row of source csv new csv files containing same names in loop.

datafile = open('source.csv','rb') reader = csv.reader(datafile) data = [] idx = [] dataidx = [] next(reader, none)#skip headers row in reader:     d = row[0]     idx.append(d)     data.append(row)     dataidx.append(row[0])  index =np.sort(np.unique(idx,return_index=true)[1])  nme = []#list of unique names row in index:     nm = data[row][0]     nme.append(nm)   in np.arange(0,9):     open(str(out_dir)+str(nme[0])+'.csv','w') f1:         row = data[i]         writer=csv.writer(f1, delimiter=',')#lineterminator='\n',         writer.writerow(row) 

the code above writes first row of new csv , stops.

my question how loop through source.csv file splitting data after every new name change , write rows same row name unique csv?

apologies long winded question problem beyond python skills unfortunately , driving me nuts.

any or suggestions appreciated

sample csv:

sample csv<br/> id  north_dms   east_dms    dist    <br/> lhgzz01 403921  374459  12500m  <br/> lhgzz01 403610  353000  12500m  <br/> lhgzz01 404640  360400  12500m  <br/> lhgzz01 404515  361900  12500m  <br/> lhgzz01 411240  381900  12500m  <br/> lhgzz01 415629  400600  12500m  <br/> lhgzz01 401503  384400  12500m  <br/> lhgzz01 400319  382200  12500m  <br/> lhgzz01 403921  372800  12500m  <br/> lhgzz02 412000  353200  12500m  <br/> lhgzz02 412749  343200  12500m  <br/> lhgzz02 403111  353000  12500m  <br/> lhgzz02 400600  374459  12500m  <br/> lhgzz02 401818  400600  12500m  <br/> lhgzz02 401525  393100  12500m  <br/> lhgzz02 401605  392400  12500m  <br/> lhgzz02 412000  384400  12500m  <br/> lhgzz02 372912  382157  8400m   <br/> gppha01 381500  382200  8400m   <br/> gppha01 393000  375252  8400m   <br/> gppha01 395400  370602  8400m   <br/> gppha01 401503  372912  8400m   <br/> gppha01 400831  382157  8400m   <br/> gppha01 390651  365700  8400m   <br/> gppha01 372912  382954  8400m   <br/> gppha02 392130  370602  12500m  <br/> gppha02 400319  364000  12500m  <br/> gppha02 400831  361900  12500m  <br/> gppha02 390651  365700  12500m  <br/> gppha02 382157  400600  12500m  <br/> gppha02 382200  401818  12500m  <br/> gppha02 375252  401525  12500m  <br/> gppha02 385112  401605  12500m  <br/> gppha02 392020  400319  12500m  <br/> gppha02 392130  392130  12500m  <br/> gppha03 392020  392020  9800m   <br/> gppha03 385112  383000  9800m   <br/> gppha03 382954  400600  9800m   <br/> gppha03 365700  364000  9800m   <br/> gppha03 381900  372912  9800m   <br/> gppha03 383000  380700  9800m   <br/> gppha03 392020  373724  9800m   <br/> gppha03 385112  363842  7500m   <br/> vvdfb01 374459  361210  12500m  <br/> vvdfb01 353000  360002  12500m  <br/> vvdfb01 360400  360002  12500m  <br/> vvdfb01 361900  364000  12500m  <br/> vvdfb01 381900  360002  12500m  <br/> vvdfb01 400600  360002  12500m  <br/> vvdfb01 384400  361210  12500m  <br/> vvdfb01 382200  350530  12500m  <br/> vvdfb02 372800  344400  12500m  <br/> vvdfb02 353200  343100  12500m  <br/> vvdfb02 343200  351448  12500m  <br/> vvdfb02 353000  360002  12500m  <br/> vvdfb02 374459  364000  12500m  <br/> vvdfb02 400600  351448  12500m  <br/> vvdfb02 393100  345353  12500m  <br/> vvdfb02 392400  341731  12500m  <br/> 

every time open file in w mode, overwrite there. should open file 1 time, loop on calls writerow like:

with open(str(out_dir)+str(nme[0])+'.csv','w') f1:     writer=csv.writer(f1, delimiter=',')#lineterminator='\n',     in np.arange(0,9):         row = data[i]         writer.writerow(row) 

instead of reopening file each iteration through for loop