python - Pandas dataframe to JSON format manipulation -


i have pandas dataframe one

user  category    rating 1     [1,2,3]     [5,1,3] 2     [3,2,1]     [3,1,1] 3     [1,3,1]     [2,1,4]

i want write endpoint takes user , returns list of categories , ratings particular user.

www.endpoint.com/user/1

should return

[{category: 1, rating: 5}, {category: 2, rating: 1}, {category: 3, rating: 3}]

is there simple way in pandas?

i use the following generic function explodes lists in columns rows:

def explode(df, lst_cols, fill_value=''):     # make sure `lst_cols` list     if lst_cols , not isinstance(lst_cols, list):         lst_cols = [lst_cols]     # columns except `lst_cols`     idx_cols = df.columns.difference(lst_cols)      # calculate lengths of lists     lens = df[lst_cols[0]].str.len()      if (lens > 0).all():         # lists in cells aren't empty         return pd.dataframe({             col:np.repeat(df[col].values, df[lst_cols[0]].str.len())             col in idx_cols         }).assign(**{col:np.concatenate(df[col].values) col in lst_cols}) \           .loc[:, df.columns]     else:         # @ least 1 list in cells empty         return pd.dataframe({             col:np.repeat(df[col].values, df[lst_cols[0]].str.len())             col in idx_cols         }).assign(**{col:np.concatenate(df[col].values) col in lst_cols}) \           .append(df.loc[lens==0, idx_cols]).fillna(fill_value) \           .loc[:, df.columns]

demo:

in [88]: df out[88]:    user   category     rating 0     1  [1, 2, 3]  [5, 1, 3] 1     2  [3, 2, 1]  [3, 1, 1] 2     3  [1, 3, 1]  [2, 1, 4]  in [89]: cols = ['category','rating']  in [90]: x = explode(df, cols)  in [91]: x out[91]:    user category rating 0     1        1      5 1     1        2      1 2     1        3      3 3     2        3      3 4     2        2      1 5     2        1      1 6     3        1      2 7     3        3      1 8     3        1      4

now can need:

in [92]: x.loc[x.user == 1, cols].to_dict('r') out[92]: [{'category': '1', 'rating': '5'},  {'category': '2', 'rating': '1'},  {'category': '3', 'rating': '3'}]

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