Pandas Set on copy warning when using .loc -


i'm trying change values in column of dataframe based on condition.

in [1]:df.head() out[2]:                gen        cont   timestamp                                                                    2012-07-01 00:00:00        0.293        0     2012-07-01 00:30:00        0.315        0     2012-07-01 01:00:00        0.0          0     2012-07-01 01:30:00        0.005        0     2012-07-01 02:00:00        0.231        0

i want set 'gen' column nan whenever sum of 2 columns below threshold of 0.01, want this:

in [1]:df.head() out[2]:                gen        cont   timestamp                                                                    2012-07-01 00:00:00        0.293        0     2012-07-01 00:30:00        0.315        0     2012-07-01 01:00:00        nan          0     2012-07-01 01:30:00        nan          0     2012-07-01 02:00:00        0.231        0

i have used this:

df.loc[df.gen + df.con <0.01 ,'gen'] = np.nan

it gives me result want warning:

a value trying set on copy of slice dataframe. try using .loc[row_indexer,col_indexer] = value instead

i confused because using .loc , think i'm using in way suggested.

for me solution works nice.

alternative solution mask, default add nan if condition true:

df['gen'] = df['gen'].mask(df['gen'] + df['cont'] < 0.01) print (df)              timestamp    gen  cont 0  2012-07-01 00:00:00  0.293     0 1  2012-07-01 00:30:00  0.315     0 2  2012-07-01 01:00:00    nan     0 3  2012-07-01 01:30:00    nan     0 4  2012-07-01 02:00:00  0.231     0

edit:

you need copy.

if modify values in df later find modifications not propagate original data (df_in), , pandas warning.

df = df_in.loc[sdate:edate].copy()

Comments

Post a Comment

Popular posts from this blog

inversion of control - Autofac named registration constructor injection -

does autofac support specifying registration name in components' constructors? example: ninject's namedattribute . you need use autofac.extras.attributed package on top achieve this so let's have 1 interface , 2 classes: public interface ihello { string sayhello(); } public class englishhello : ihello { public string sayhello() { return "hello"; } } public class frenchhello : ihello { public string sayhello() { return "bonjour"; } } then have consumer class, in want select instance injected: public class helloconsumer { private readonly ihello helloservice; public helloconsumer([withkey("en")] ihello helloservice) { if (helloservice == null) { throw new argumentnullexception("helloservice"); } this.helloservice = helloservice; } public string sayhello() { return this.helloservice.sayhello()...
Read more

verilog - Systemverilog dynamic casting issues -

i've code snippet following in testbench function void write_to_port( my_data_type_base data ); my_data_type_extended data_ext; if(!$cast(data_ext, data)); `uvm_error(get_type_name(), "failed cast"); `uvm_info(get_name(), $psprintf("data_ext :\n%s", data_ext.sprint()), uvm_medium) // write data_ext out port.... endfunction when run it, i'm getting uvm_error "failed cast." i'm not quire sure why $cast not returning 1. can see, i'm printing out extended class data item after casting uvm_info. can see it's being cast properly. if don't use $cast if condition, don't runtime error. isn't coding practice use if dynamic cast check if $cast returning 1 ? what might reason behind cast not returning 1 in above case? i think semicolon on line 'if' not belong? i think consumes if statement, , uvm_error executes regardless of how if evaluates: if(!$cast(data_ext, data)); <- no semico...
Read more

ios - Change Storyboard View using Seague -

i have following code checks connection server, , depending on want change views if no connection found. nsstring *connect = [nsstring stringwithcontentsofurl:[nsurl urlwithstring:@"http://myserver.com"] encoding:nsutf8stringencoding error:nil]; if (connect == null) { [self performseguewithidentifier:@"network_failure" sender:self]; } else { // other code here } my problem not change views. have added storyboard segue between 2 views identifier of network_failure . not have navigation controller or that, problem? thanks help! no not problem. first of all, in objectivec exists nil object oriented null . must use that. so: if(connect == nil) or better: if(!connect) so due fact nil not same of null , probably code does't enter in if scope . you have been able discover breakpoint. anyway: be sure set trigger segue (line) 2 view controller , , name network_failure (that not best name. should instead view1toview2 ) as, m...
Read more