dataframe - r apply function pads spaces to match character lengths -

-

i using apply generate strings data frame.

for example:

df2 <- data.frame(a=c(1:3), b=c(9:11)) apply(df2, 1, function(row) paste0("hello", row['a'])) apply(df2, 1, function(row) paste0("hello", row['b']))

works expect , generates

[1] "hello1" "hello2" "hello3" [1] "hello9" "hello10" "hello11"

however, if have

df <- data.frame(a=c(1:3), b=c(9:11), c=c("1", "2", "3")) apply(df, 1, function(row) paste0("hello", row['a'])) apply(df, 1, function(row) paste0("hello", row['b']))

the output is

[1] "hello1" "hello2" "hello3" [1] "hello 9" "hello10" "hello11"

can 1 please explain why padded space make strings same length in second case? can work around problem using gsub, have better understanding of why happens

this happening because apply transforms data.frame in matrix. see happens when coerce df matrix:

 as.matrix(df)        b    c   [1,] "1" " 9" "1" [2,] "2" "10" "2" [3,] "3" "11" "3"

notice coerced character matrix , included space on " 9".


Comments

Post a Comment

Popular posts from this blog

python - No exponential form of the z-axis in matplotlib-3D-plots -

-
Image
i have similar problem described in how prevent numbers being changed exponential form in python matplotlib figure : i don't want (in special case) weird scientific formatting of axis. problem different have problem @ z -axis. 2-d plots can use ax.get_yaxis().get_major_formatter().set_useoffset(false) . , there no function ax.get_zaxis() what use format z -axis same way? edit: example: from mpl_toolkits.mplot3d import axes3d import numpy np import sys import matplotlib import matplotlib.pyplot pyplot def func(xi, ti): res = 10e3 + np.cos(ti) * np.sin(xi) return res if __name__ == '__main__': timespacing = 20 timestart = 0 timeend = 1 time = np.linspace(timestart, timeend, timespacing) widthspacing = 50 widthstart = 0 widthend = 3 width = np.linspace(widthstart, widthend, widthspacing) reslist = [] matplotlib.rcparams['legend.fontsize'] = 10 fig = pyplot.figure() ax = fig.gca(projection = '3d...
Read more

php - Best Light server (Linux + Web server + Database) for Raspberry Pi -

-
i install web server database on raspberry pi (little computer). computer has 1gb ram. i want know best combination: linux distribution , web server , dbms run local server multiple users minimal latency, use php on server. , best settings performance , not have bugs (memory usage, disable plugin, disable service, etc)? i thought light debian , lighttpd server , sqlite database. solution? i think lighttpd + sqlite great choice. linux distro, debian @ centos or tiny core linux , although i'm not sure of compatibility pi. obviously, can't go wrong raspbian if want use in production , more stable performance, few more pi's , set them in cluster .
Read more

c# - "Newtonsoft.Json.JsonSerializationException unable to find constructor to use for types" error when deserializing class -

-
i developing app in xamarin android. have splash screen serialize class , pass mainactivity using intent . when try deserialize in mainactivity error message : "serializationexception unable find constructor use types" serialization : void loaddata() { currency currency = new currency(this); intent = new intent(this, typeof(mainactivity)); intent.putextra("currency", newtonsoft.json.jsonconvert.serializeobject(currency)); startactivity(intent); } deserialization : cur = newtonsoft.json.jsonconvert.deserializeobject<currency> (intent.getstringextra("currency")); // error here class constructor : public currency(context context) { thiscontext = context; } i began experiencing problem after added parameter context context constructor. has caused this? how can solve it? possible serialize/deserialize class has parameters? you need have empty constructor in currency class in order deserialize it. ...
Read more